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Hydraulic fracturing is routinely used to release and produce petroleum from multistacked shale layers. Although it is known that some shale layers are more productive than others, actually allocating produced oil volumes to individual reservoirs is difficult. In this paper, we introduce a new allocation technique that is based on the heterocompounds (nitrogen-, sulfur-, and oxygen-containing) detected by electrospray negative-ion ESI(−) Fourier transform ion cyclotron resonance mass spectrometry. A total of 2 oils and 5 mixtures thereof prepared in the laboratory, 4 produced oils and 2 shale bitumens extracted from the Vaca Muerta Formation (Argentina), and 5 produced oils and 15 shale bitumens extracted from the Niobrara Formation were used to test and illustrate the utility of the newly developed technique. The allocation results show a good match to conventional geochemistry indices based on gross polarity fractions, C27-28-29 diasteranes, pristane, and phytane. The chemostatistic allocation method is capable of deconvoluting the contributions of individual shale layers using bitumen extracts and is not influenced by fractionation. The newly developed allocation technique can assist in the rapid development of multistacked shale reservoirs. Allocating point source or genetic contribution to a conventional oil play is another potential application (i.e., oil-source correlation).

Purpose The purpose of this paper is to use the novel data from the primary vision to determine the main financial and economic drivers of this revolutionary shale oil production and how these drivers changed after 2016 when the US removed its oil-exporting ban. Design/methodology/approach In this paper, the authors use the vector autoregressive model to assess the dynamic relationships among the Frac Count (FSCN) from the primary vision and the set of financial/macro-economic variables and how this dynamic relationship is altered with the effects of the US export ban before and after the lifting of the export ban. Findings The empirical evidence reveals that a positive shock to New York Mercantile Exchange, Standard and Poor’s 500, rig count, West Texas Intermediate or the US ending oil stocks increase the FSCN but higher interest rates and oil production decrease the FSCN. After the US became one of the major oil producers, it removed its crude export ban in December 2015. The empirical evidence suggests that the shale oil industry gets more integrated with the financial system and becomes more efficient in its production process in the post-2016 era after the export ban was removed. Originality/value The purpose of this paper is to use the novel data from the primary vision to determine the main financial and economic drivers of this revolutionary shale oil production and how these drivers changed after 2016 when the US removed its oil-exporting ban.

The article provides an analysis of shale oil production and artificial lift equipment world market for choosing the optimal method for oil production from the Bazhenov formation. The result of the analysis is the identification of prospective complexes of artificial lift (wellhead and downhole) equipment that meet the following conditions: • artificial lift equipment is used in operating conditions that are similar to those, which planned for the Bazhenov formation development: for wells with a long horizontal wellbore and multi-stage hydraulic fracturing; conditions similar to the Bazhenov formation in terms of the depth of the deposit, production volumes (production curve, initial flow rates, gas-oil ratio (GOR), reservoir temperature, etc ).; • the properties of the produced fluid are similar to the Bazhenov formation reservoir fluid (light oil, GOR increase over production time, water cut drop over time, etc. Analysis includes wellhead equipment, downhole equipment, and control stations for wellhead and downhole equipment. Based on the analysis results, the main selection criteria are given, a comparative analysis of the main types of artificial lift equipment is carried out, and promising types of artificial lift for oil production from the Bazhenov formation are identified.

The CO2 Huff-n-Puff process enhances the shale oil production and it could incur a risk of forming asphaltene, causing damage to the formation. During the process, the effects of aqueous solubility of CO2 and nano-confinement affect the amount of CO2 interacting with asphaltene-bearing oil, phase behavior of fluid determining the asphaltene deposition, CO2 storage, and oil production. Therefore, this study quantifies the effects of the aqueous solubility of CO2 and the nano-confinement on the performance of the CO2 Huff-n-Puff process and the asphaltene formation in a tight formation. When the aqueous solubility of CO2 is considered in the CO2 Huff-n-Puff process, a fraction of the injected CO2 dissolves in the brine, indicating the CO2 sequestration through solubility trapping. Decreasing oil production by 4% is also obtained with a reduction in asphaltene deposition. When the process undergoes the nano-confinement effect, higher oil production by up to 14% and more asphaltene deposition are observed. This study emphasizes that the aqueous solubility of CO2 and the nano-confinement effects are necessary factors in accurate predictions of the oil production, CO2 sequestration, and asphaltene formation during the CO2 Huff-n-Puff in confined formations.

In light of the U.S. shale oil boom and given that commercial shale oil production has been mostly confined to the USA, this paper disentangles the oil supply determinant into its U.S. and non-U.S. production components, and studies their impact on U.S. real personal consumption expenditures (PCE) and on U.S. index of consumer sentiment (ICS). First, I estimate a structural VAR model to identify and study the effect of structural shocks in the crude oil market on PCE and ICS. The results show that while PCE and ICS respond negatively to oil demand shocks, they respond differently to oil supply shocks. While ICS experiences transitory negative response to both oil supply shocks, PCE shows that the response of inflation and output differs depending on whether the oil supply shock is domestic or foreign. Second, I compute the forecast-error-variance decompositions to quantify the contribution of oil supply and demand shocks to the historical fluctuations in PCE and ICS. My findings reveal that most of the variation in PCE is explained by oil supply shocks—unlike ICS where most of its variation is explained by aggregate demand shocks. Third, I conduct a historical decomposition exercise to examine the contributions of structural oil shocks in explaining historical changes in PCE and ICS. My results indicate a strong presence of U.S. oil supply shock in boosting ICS during the 2014 period of the oil price drop. Finally, the results that not all oil supply shocks are alike are robust to alternative measures of real economic activity.

The stock market performance of the US oil industry is evaluated against a combination of benchmarks before and after the US shale oil revolution, in order to ascertain whether the increase in US shale oil production had an adverse impact on oil industry stock market returns. In 2014, the dynamic of the global crude oil supply-demand situation was such that the oil price fell because of the increased US crude oil production. Saudi Arabia and the other major producers preferred to have low oil prices, at least temporarily, in order to penalize the US shale oil players. Any oil price increase since then is seen as leading to an increase in US crude oil supply which then further reduces oil prices. The oil industry outperformed the benchmarks prior to the ramp up of US crude oil production led by the shale oil revolution, but the industry underperformed the benchmarks after these production increases. Hence, the US shale oil revolution did ruin the oil industry stock market returns. Several topics for discussion are included: The US Shale Oil Revolution; World Crude Oil Markets; Crude Oil Price Dynamics in the US; and Crude Oil Price Impacts on Oil Companies.Keywords: Shale Oil Revolution, Crude Oil Price, Oil and Gas Industry, Stock Market ReturnsJEL Classifications: Q32, Q41, Q43DOI: https://doi.org/10.32479/ijeep.9171

The horizontal rotary retort is one of the important equipment in oil shale retorting by solid heat carrier technology, in which the heating of oil shale plays a crucial role in shale oil production. In this work, a comprehensive heat transfer model including both conduction and radiation under contact and non-contact conditions was proposed to numerically investigate the heat exchange among particles at five different pathways by employing the discrete element method (DEM). The effects of particle physical parameter (particle size) and operating conditions (rotational speed and fill ratio) on thermal characteristics such as oil shale heating time, thermal rate, thermal index and heat flow were deeply analyzed. In summary, the heat flow generated by particle-fluid-particle heat conduction contributed 66–71% of the total heat flow, the radiative flow produced by particle-particle heat radiation was 22–30%, and the thermal contribution of particle-particle heat conduction was the least, accounting for only 6–7%.

Based on formation testing data of more than 40 wells with industrial oil flow, systematic observation of 1 010.26 m long cores taken from 4 wells and test data of over 10 000 core samples combining with drilling and pilot fracturing data of multiple wells, the geological characteristics of the upper submember of the Sha 4 Member to the lower submember of the Sha 3 Member of Paleogene (Es4s-Es3x) in the Jiyang Depression were investigated to find out factors controlling the enrichment of shale oil and the accumulation model of shale oil, and a comprehensive evaluation method for shale oil sweet spots was established. It is found through the study that the target shale layer is characterized by strong heterogeneity, weak diagenesis, low thermal evolution and high content of clay and carbonate minerals. Shale lithofacies, microcrack, thin interlayer and abnormal pressure are the main factors affecting enrichment and stable production of shale oil, the organic rich laminar shale has the best storage and oil-bearing capacity, microcrack network system improve the storage capacity and permeability of the shale, the thin interlayer is the main flow channel for stable shale oil production, and the abnormal high pressure layer is rich in free state shale oil and high in oil content. The shale oil layers in the target section were divided into three types: matrix, interlayer and fracture ones. According to the occurrence state and exploration practice of shale oil at home and abroad, it is concluded that the interlayer shale oil is the most profitable type at present. The selection parameters for the different types of shale oil were determined, and accordingly the favorable areas were pointed out by comprehensive evaluation of multiple factors. Vertical wells in the interlayer shale oil reservoir, such as Fan 159, Fan 143 and GX 26, were stimulated by volume fracturing and high conductivity channel fracturing jointly. After fracturing, they had a daily oil production of over 6 t, up to 44 t, and stable productivity. Shale oil is expected to become an important replacement energy resource in the Jiyang Depression. Key words: shale oil, enrichment elements, enrichment model, shale oil sweet spot, lithofacies, microcrack, thin interlayer, abnormal pressure, Jiyang Depression

Purpose The purpose of this study is to investigate the predictability of crude oil price and shale oil production, in a bid to examine the possibility of bi-directional causality. Design/methodology/approach The study adopts a recently developed predictability model by Westerlund and Narayan (2015), which accounts for persistence, endogeneity and heteroscedasticity. It also accounts for structural breaks in the predictive models. Findings The empirical results show that only a unidirectional causal relationship from crude oil price to shale oil production exists. This happens as crude oil price appears to be a good predictor of shale oil production; however, shale oil production does not serve as a good predictor for crude oil price. Accounting for structural break was found to improve the predictability and forecast accuracy of the predictive model. Our result is robust to choice of crude oil price benchmarks (West Texas Intermediate, Brent, Dubai Fateh and Refiners’ Acquisition Cost) and their denominations (real or nominal). Research limitations/implications The result implies that crude oil price must be considered when predicting shale oil production. Meanwhile, the non-significance of shale of production in crude oil price predictive model provides information to potential analyst, researchers and countries predicting crude oil price that failure to account for the effect of shale oil production would not have significant impact on the forecast accuracy of their models. Originality/value The study contributes originally to the literature on crude oil price–shale oil production in four major ways. First, it applies a recently developed predictability method by Westerlund and Narayan (2015), which is more suitable for dealing with persistence, conditional heteroscedasticity and endogeneity in the predictors. Second, it investigates existence of reverse causality between crude oil price and shale oil production. Third, it examines the variation in the response and effect of four major crude oil price benchmarks. Fourth, it considers crude oil price in both real and nominal terms.

The shale oil wells drilled in the early stage of the Jiyang Depression have achieved industrial-scale flow, but the oil production in special exploration wells has been less than ideal. The area of continental shale oil and gas accumulations has not been properly controlled, and geological sweet sections and sweet areas need to be systematically studied. In this study, shale reservoir characteristics are analyzed in detail based on thin sections, field emission scanning electron microscopy (FE-SEM) observations and mercury injection experiments of well core samples combined with X-ray diffraction (XRD) and geochemical indicators. Key factors related to a high yield of shale oil are determined in addition to the shale oil production capacity, and the types of shale oil sweet spots are classified, while the sweet spot distribution pattern is determined. The results show that the Paleogene shale in the Jiyang Depression is rich in carbonate minerals (mainly calcite and ferrocalcite, followed by dolomite and ferrodolomite) and has a low clastic content, high organic carbon content (2.0–7.0 wt%), and medium maturity (Ro = 0.51%–1.1%). An effective reservoir space assemblage usually has a three-tier intercommunication form within the porosity-fracture network. Laminar lithofacies that are rich in carbonates are the most favorable for containing continental shale oil reservoirs. Shale oil geological sweet spots can be roughly divided into matrix shale oil, fracture shale oil, interlayer shale oil, and compound shale oil types. The key focus in locating shale oil wells is to find geological sweet spots that have an appropriate organic matter (OM) content, interlayer development, light oil, and high pressure. This study demonstrates that favorable sweet spots are found to have the following conditions: a shale formation pressure coefficient of >1.2, shale total organic carbon content of >2%, organic-rich laminar lithofacies (including interlayer and single-interlayer thicknesses of >2 cm), burial depth of >3200 m, middle diagenetic stage B (Ro > 0.7%), and crude oil density of

Historically, the price of WTI crude oil futures has long been higher than that of Brent by $2/barrel, but the spread between 2011 and 2015 was reversed and expanded to $24/barrel. In order to analyze the difference between two crude oil price variables with the same trend and phase separation using one method of analysis, this paper constructs a dynamic comparative analysis framework using the method of time-point decomposition of fluctuation factors to determine the different reasons and amplitudes for monthly fluctuations in the two price systems in the sample interval. The study found that the sensitive response of Brent futures price indicators to the world’s crude oil supply resulting from the depletion of oil in the North Sea oil field prompted it to rise in 2011–2015. For the WTI price system, due to the increase in the US shale oil production after 2008 and the restrictions in domestic pipeline transportation capacity, the increase in the Cushing crude oil inventory caused downward pressure on the WTI price. With the lifting of the US crude oil export ban in December 2015, arbitrage space disappeared, and the spread between the two gradually narrowed.

In the last years, the huge success of shale gas and oil exploitation in North America and enhanced oil recovery by injecting carbon dioxide have attracted more attentions in petroleum industry. The reasonable scheme for shale oil production is a key step for sustainable and high-efficiency products of shale resources, which is dependent on the basic law of liquid flow. In this paper, a multiscale model is established based on homogenization theory to investigate the law of liquid flow within shale system. Considering the results of molecular dynamics simulation, the Navier-Stokes equation coupled with slip boundary is used to describe the liquid flow within microscale domain and the slip-corrected Darcy-like transport model in which clear physical meaning can be shown for every parameter can be derived for macroscale domain. In order to validate derived model, three cases including water and oil flow within simple nanopores are implemented and the results show that homogenization models match well with the results of molecular dynamics simulation for water flow with different contact angle and oil flow within inorganic pore. However, high-order slip-corrected model will deviate from the molecular dynamics simulation for oil flow within simple organic pore when pore size is smaller than 5.24 nm. Then the fractal porous medias are reconstructed based on Monte Carlo simulation and the several critical parameters are discussed. Finally, the results of homogenization model are applied in reservoir scale model to investigate shale oil production performance for economic evaluation and production optimization.

Accurate apparent permeability (AP) model for oil transport in shale must consider natural fractures and micro/nano-pores within organic matter and inorganic matrix. Furthermore, the effect of pore geometry, tortuosity, pore size distribution (PSD), the spatial distribution of different pores, total organic content (TOC), and liquid slip should also be taken into account. However, all of the aforementioned factors are not simultaneously considered in one AP model. In this work, we develop an AP model in 3D for shale oil to overcome this drawback. We first validate our model by comparing with the published data. Then sensitivity analysis for some parameters is investigated. After that, shale oil APs are used in a macro-scale reservoir simulation model. In this way, the effect of some micro-scale factors on production performance can be quantitatively evaluated. Notably, on the basis of embedded discrete fracture model (EDFM), our reservoir simulation model considers non-linear flow in shale matrix, complex hydraulic fracture geometry, and pressure-dependent permeability of hydraulic fractures. Results show that natural fractures contribute the most to AP, followed by organic pores and inorganic pores. In general, the AP in the horizontal direction is approximately twice that in the vertical direction in shale. Furthermore, the maximum error caused by the pore type on shale oil production is ∼31%, followed by tortuosity (∼25%), pore shape (∼13%) and slip effect (∼4.8%). In conclusion, it is necessary to simultaneously incorporate the influences of the aforementioned factors. Our stochastic permeability model can serve as an efficient tool to determine shale oil AP.

In the paper, we study the long-run relationship in the WTI-Brent oil time series, taking into account the occurrence of two relevant events: the rise of shale oil production, in early 2011, and the widening and closing of the WTI-Brent price spread, from 2011 to 2014. Monthly data of WTI and Brent crude oil prices, as well as US shale oil quantities from January 2000 to December 2017 is used for the analyses. The empirical results of the cointegration tests with structural breaks show that two structural break occurs, in February 2011 and in October 2014. We then estimate a Vector Error Correction Model (VECM), considering the structural break suggested by the cointegration test results, the timing of the rise in shale oil production and the dynamics of the WTI-Brent price spread. Our analysis reveals that WTI and Brent crude oil prices have had a long-run relationship up to 2011; no cointegration existed during the period of widening of the spread; again, a new long-run relationship arises after the closing of the gap, which includes the shale oil production. In the last period, the cross price elasticity of Brent on WTI slightly reduces compared to the pre-2011 era, whilst the shale oil production increases its importance in explaining the long-run relationship between WTI and Brent fivefold. Using the Generalized Impulse Response Functions (GIRFs) we finally study the impact of exogenous shocks on the variables, showing that in the first period, with limited shale oil production, oil prices reacted to shale oil and not vice versa. After October 2014, the opposite becomes true and shale oil production follows changes in both WTI and Brent prices.

The shale oil revolution in the United States had an irreversible impact upon the global oil market and was a key factor determining oil price reduction in 2014-2016. One of the main reasons for the rapid growth of the shale oil production in the US was the development of extracting technologies, which reduced the cost of production to an acceptable level. This article studies the problems of long-term forecasting in shale oil production and the productivity of drilling rigs. This research applies the fitting of an asymmetric bell-shaped function using an OLS approach. This function is derived as an analytical solution of the differential equation for oil production.Another innovation of this study is the asymmetric function, which correlates better with data on the extraction of traditional and non-traditional oil resources. An analysis of the empirical data with the derived asymmetrical bell-shaped curve shows that the productivity of drilling rigs will peak by 2026 at 1,200 bbl per day, which is 2 times higher than the current level. The peak of production would correspond to the maximum oil production of 11.3 mln bbl per day and to technically recoverable resources of 96 bln bbl. This could mean that starting from 2023, the volume of shale oil production in the US may not be enough to meet the growing global demand for oil and other resources with even higher production costs should be developed. The theoretically grounded and practically tested asymmetrical bell-shaped curve can serve as one of the tools for assessing the long-term impact of technological innovation and the growth of equipment productivity upon the development of oil production in the US in the course of Foresight studies.

This study aims to compare the pyrolysis behavior of Huadian oil shale in two infrared heating fixed bed reactors with different directions of infrared beam. Our previous work has shown that fast pyrolysis of oil shale conducted in the shallow fixed bed infrared heating reactor (co-current) presented the massive secondary reactions, which lowered the shale oil production (Siramard et al., 2017). Conversely, the cross-current infrared achieved shale oil yields higher than the Fischer Assay oil yield (13.07 wt% of dry basis), such as 117.7% of the Fischer Assay yield at our realized highest heating rate of 7 °C/s under a specified pyrolysis temperature of 550 °C. The shale oil from the cross-current infrared heating reactor was obviously heavier than the oil obtained from the co-current heating reactor. Thus, the infrared cross heating evidently suppressed the secondary reactions toward volatile. Our realized shale oil yield could reach 13.67 wt% or 122.5% of the Fischer Assay yield under reducing pyrolysis pressure of 0.6 atm, indicating that lower pressure is also beneficial to the release of volatile and reduction of the secondary cracking reactions. This work shows essentially that the infrared cross heating provides an effective merge of the advantages from quick heating and minimization of secondary cracking reactions to enable the shale oil yields being higher than the Fischer Assay oil yield. Keywords: Pyrolysis, Secondary cracking, Volatile, Infrared heating, Oil shale

Given that the booming U.S. shale oil has reshaped the global oil landscape, better forecasting output of U.S. shale oil can facilitate to better understanding the global oil trend. To more accurately forecasting U.S. shale oil production, we hybridize the nonlinear- and linear-forecasting model to a new forecasting technique in two step: (i) combining a nonlinear grey model with the mentalism idea to develop nonlinear metabolism grey model (NMGM), (ii) combining the proposed NMGM with Auto Regressive Integrated Moving Average (ARIMA) to develop NMGM-ARIMA technique. The sliding validation experiments with the previous U.S. shale oil quarterly output dataset of 2003–2008 and 2008–2013 are adopted to verify the feasibility of the proposed NMGM-ARIMA technique. The empirical results show that this novel NMGM-ARIMA technique can significantly improve forecasting effectiveness and outperform other related four forecasting models. We therefore believe that the proposed forecasting technique can service researchers, policymaker, analysists and others stakeholders to more timely and accurately forecasting U.S. shale oil output and thus better understanding global oil market.

The global energy landscape is changing rapidly, and the main driver of these changes in the twenty-first century was the shale oil that occurred in the United States of America. However, its environmental and economic consequences are still not known in detail. The impressive increase in shale oil production has led to a profound change in the world energy markets, as oil prices have pushed lower, especially after 2014. This study highlights the effects of fluctuations in world oil prices on shale oil investment through our analysis of oil prices, long-term and short-term debt, costs, and liquidity flowing. The study found that political events in the Middle East have accelerated the shale oil industry's growth. The fall in oil price is one of the new challenges facing the fossil energy market in the United States and is pushing investors to hesitate to enter the industry.

As one of the most important unconventional hydrocarbon resources, the oil shale has been extracted with a frozen wall to successfully increase the shale oil production and reduce environmental pollution, which results from the harmful liquids in the in situ conversion processing of oil shale. Thereby, the strength and permeability of the frozen wall are extremely critical to reduce the harmful chemicals leaching into the groundwater. However, the permeability and strength of the frozen wall can be influenced by periodic freeze-thaw cycles. In order to investigate the damage and deterioration characteristics of oil shale samples after various periodic freeze-thaw cycles, the oil shale samples were periodically frozen and thawed as many as 48 times, after which the sample mass, stress-strain, freeze-thaw coefficient, uniaxial compressive strength, elastic modulus, and longitudinal wave velocity of the oil shale samples were separately measured. According to the measured results, the number of freeze-thaw cycles greatly influenced the physical and mechanical properties of oil shale samples. The uniaxial compressive strength and elastic modulus of the oil shale samples were changed with maximum variation rates of 64% and 65%, respectively. Meanwhile, the freeze-thaw coefficient of measured oil shale samples exponentially decreased with the increased number of freeze-thaw cycles, whereas the longitudinal wave velocity of tested samples ranged from 1602 m/s to 2464 m/s as a result of the new micropores inside the oil shale sample. Research results have enormous significance to the efficient and safe in situ exploitation of oil shale deposits.

Oil and gas production from unconventional reservoir has grown dramatically in recent years, especially in shale reservoir. However, the conventional hydrodynamic approaches are not sufficient to describe the fluid occurrence state and flow in shale reservoir due to its widely distributed nano/mesopores and various mineral types. The effect of water on oil adsorption and transport in shale nanopores is unclear. Understanding the fluid adsorption and transport behavior in shale nanopores is essential for shale oil development. In this study, equilibrium molecular dynamics (EMD) simulation method is utilized to investigate the single phase oil and oil-water two phase adsorption behavior in clay mineral nanopores of shale. The pressure driven flow is simulated based on nonequilibrium molecular dynamics (NEMD) to investigate the fluid transport. The results show the slip boundary condition between single phase oil and surface, which leads to the breakdown of Darcy’s law for oil flow. Water has preferential adsorption on the clay mineral surface and oil presents in the middle of the nanopore, forming a layered structure. The existence of water reduced the oil adsorption and self-diffusivity in montmorillonite nanopores. For water-oil two phase flow, when oil-surface interaction completely shielded by water film, Darcy’s law still feasible for oil. Water enhanced the flow of oil in MMT nanopore due to a decrease in the friction of oil with the surface. This work advances the understanding of water effects on oil flow in confined shale nanopores, which provides the theoretical support on enhancing shale oil production.

In Estonia the significant part of power generation is still based on firing oil shale fuel in thermal power plants despite of the growth of the share of the green energy in recent years. Electricity generation is based on power units utilizing different combustion technologies. A significant part still comprises old units with capacity 185-195 MWe commissioned in early 70s of last century. These pulverized combustion (PC) based units utilize oil shale as a fuel and are operating with subcritical steam parameters, characterizing by relatively low efficiency 26 - 30% (net, LHV based). Due to their low performance, operational issues (intensive fouling of heating surfaces), and remarkable environmental impact, these units were decommissioned or retrofitted with boilers implementing circulating fluidized bed combustion (CFBC) technology in 2004-2005. Implementation of CFBC technology for oil shale combustion significantly reduced both operational issues and environmental impact. With some additional modifications in turbine island allowing to increase rated capacity up to 215 MWe and after increasing steam parameters, the net efficiency of up to 37% was achieved. Consequently, the specific CO2 emissions in the range of 0.99 – 1.05 t/MWhe depending on quality of oil-shale used, was achieved. Recently, the new 300 MWe CFBC based power unit was commissioned. It is operating with subcritical steam parameters: live steam temperature 565 °C and pressure 17 MPa. Net efficiency (LHV based) of that unit is 40 % and specific CO2 emissions up to 0.9 t/MWhe in case of firing only oil shale. In this study the technical viability of retrofitting oil shale based power generation units with CC is described. In the analysis two CC methods were considered: post-combustion (assuming conventional amine process) and oxy-fuel combustion. Among other CC technologies these processes are at the present time characterized by higher technical readiness level, can be applied for existing units with minimal modifications and are applicable for oil shale fuel with it specifics. Besides power generation, Estonia has for almost 100 years of experience in production of shale oil through thermal decomposition of oil shale kerogen in retorts. Currently, solid heat carrier (SHC) method is the main method used for producing shale oil. In this method, direct CO2 emission comes from the preparation of SHC by combustion of solid retorting residue (semi-coke). Mainly two combustion methods are presently applied: lift pipe combustion and CFBC which was recently successfully integrated into shale oil production process. The possibility of utilizing CC technologies in shale oil production units and their technical analysis is described in this study.

Lacustrine shales hold a huge potential oil resource in China. Pore properties (pore volume, diameter, specific surface area, and fractal dimensions) and their relationships with geological factors (mineralogy, insoluble organic carbon, burial depth, and vitrinite reflectance) are critical for evaluating shale oil resource. However, the factors controlling pores for lacustrine shale oil remain unclear, as the relationships between pore properties of Soxhlet-extracted samples and geological factors have not been studied using multivariate analytical methods. In this paper, the samples from the lacustrine shale in the upper part of the Sha-4 Member of the Paleogene Shahejie Formation in the Dongying Depression were tested with a set of experiments including Soxhlet (solvent) extraction, X-ray diffraction mineral analysis, insoluble organic carbon, vitrinite reflectance, and low-pressure CO2 and N2 adsorption experiments. The micromesopore volume varies from 0.003 cm3/g to 0.045 cm3/g. The relationships of pore properties with geological factors were studied with partial least square regression analysis (PLSR analysis, a powerful multivariate regression analysis). The results of the PLSR analyses indicate that clay minerals and carbonates are two key factors affecting the pore properties of the lacustrine shale. Compared with marine shales, more clay minerals in the lacustrine shale make them become more important for controlling pores than organic matter. The PLSR results also illustrate that the shale with higher pore volume contains more clay minerals and fewer carbonates and thus is unfavorable for hydraulic fracturing. Therefore, the shale with high micromesopore volume may be unfavorable for shale oil production. The shale with the modest micromesopore volume (~0.036 cm3/g), relatively high content of brittle minerals (~71 wt%), and low clay mineral content (~29 wt%) is conducive to both oil storage and hydraulic fracturing for the development of the Es4U shale oil in the Dongying Depression in East China.

This paper deals with the analysis of (spatial) crude oil production divergence in the United States, paying particular attention to the domestic crude oil production between PADD 2 and PADD 3, which are the areas in which the bottleneck occurs and has a direct implication on the price of West Texas Intermediate (WTI). To this purpose, we use techniques based on fractional integration, fractional cointegration VAR (FCVAR) and wavelet analysis. Monthly data related to the oil production in the U.S. by regions (Anadarko, Appalachia, Bakken, Eagle Ford, Haynesville, Niobrara and Permian) from January 2007 to June 2020 are used. The results, using fractional integration and cointegration techniques, indicate that the time series analyzed are highly persistent and there is evidence of long run equilibrium relationships in some of the series. Finally, using wavelet analysis, we conclude that the most affected areas are Anadarko, Appalachia, Haynesville and Niobrara where an increase in the shale oil production is followed a decrease in WTI crude oil prices. pre-print 1644 KB

Summary Economic production from shale oil reservoirs relies on the longevity of conductive fractures. Choke or drawdown management is believed to better preserve the fracture conductivity during the early life of the wells, which thus potentially leads to a higher ultimate oil recovery. However, there is no strong consensus among the previous literature as to whether choke management can offer the incremental oil recovery in the long-term. Even if it can, the mechanism is not well understood, and the economic benefit can be challenged, because the choke management slows down the early oil production, which is worth the most in terms of Net Present Value (NPV). In this study, a series of coupled flow-geomechanical numerical simulations is performed to examine the effect of choke management on the ultimate oil recovery and NPV. We built multiple reservoir realization models, each of which is validated based on the same field production data from Middle Bakken shale-oil reservoirs to perform probabilistic production forecasts. The different reservoir realization models are built to assess the uncertainty in the Stimulated Reservoir Volume parameters, including natural fracture spacing, water saturation in the matrix and fracture, and formation compressibility. The different reservoir parameters lead to each model having different primary recovery driving mechanisms of oil recovery, including imbibition and compaction drive. In each simulation run, stress-dependent permeability phenomena during fracturing and flowback are modeled to more closely simulate proppant crushing and embedment. Our model carefully simulates the matrix, natural, and hydraulic fractures separately, because each of these media demonstrates different stress sensitiveness. This study quantitatively demonstrates that the choke management seems to increase both the ultimate oil recovery and NPV if the oil recovery is strongly driven by imbibition. A mechanistic discussion for this claim is presented. We have also shown that this claim can straighten out the mixed conclusions among some previous papers. As a result, this study proposes the evaluation of the dominant driving mechanism of shale-oil recovery for the optimum design of the choke management. Moreover, this study also attempts to propose the optimum ramping-down rate of the choke. For example, if the reservoir demonstrates a strong imbibition, the optimum choking rate is between 500 and 100 psi/day. Meanwhile, if the reservoir demonstrates a weaker imbibition, the optimum choking rate is between 50 and 10 psi/day. These optimum range is shown to be consistent, regardless of the objectives, whether to optimize the ultimate oil recovery or NPV.

Figuerola-Ferretti thanks the Spanish Ministry of Education and Science for support under grants MICINN ECO2010-19357, ECO2012-36559 and ECO2013-46395, and McCrorie, The Carnegie Trust for the Universities of Scotland under grant no. 31935. This paper provides an analysis of oil prices during and in the aftermath of the Global Financial Crisis, concentrating on the 2007-08 price spike and the 2014-16 price decline. The mildly explosive/multiple bubbles testing strategy by Phillips, Shi and Yu (2015, International Economic Review 56(4), 1043-1133) is used to test for price departures from an underlying stochastic trend and to assess whether any such departures can be explained by fundamentals or other proxy variables. The test dates two significant time periods in both Brent and WTI nominal and real front-month futures prices: a mildly explosive episode during the 2007-08 spike, prior to the peak of the Global Financial Crisis; and a significantly shorter, negative such episode during the 2014-16 price decline, whose commencement is dated around a key OPEC meeting in November 2014. Evidence using other commodity prices points to explanatory factors beyond commodity markets. A global economic activity proxy is found to be decisive in the episode in mid-2008; excess speculation is not. U.S. shale oil production, though contributing to the post-June 2014 price decline, is not seen to have been decisive. Against some recent work tying the CBOE Volatility Index (VIX) to oil futures prices, we find no evidence that the VIX decisively affected oil price levels during the sample period. The results are compared and contrasted with those obtained by Baumeister and Kilian (2016, Journal of the Association of Environmental and Resource Economists 3, 131-158) via a forecasting approach based on a structural vector autoregressive model without financial variables. Taken altogether, the results herein provide new evidence based on formal statistical testing that helps resolve a number of recent controversies in the oil price literature. Postprint

It is a general understanding that unconventional oil is petroleum-extracted and processed into petroleum products using unconventional means. The recent growth in the United States shale oil production and the lack of refineries in Canada built for heavy crude processes have resulted in a significant increase in U.S imports of unconventional oil since 2018. This has increased the risk of incidents and catastrophic emergencies during the transportation of unconventional oils using transmission pipelines and train rails. A great deal of effort has been made to address the remediation of contaminated soil/sediment following the traditional oil spills. However, spill response and cleanup techniques (e.g., oil recuperation, soil-sediment-water treatments) showed slow and inefficient performance when it came to unconventional oil, bringing larger associated environmental impacts in need of investigation. To the best of our knowledge, there is no coherent review available on the biodegradability of unconventional oil, including Dilbit and Bakken oil. Hence, in view of the insufficient information and contrasting results obtained on the remediation of petroleum, this review is an attempt to fill the gap by presenting the collective understanding and critical analysis of the literature on bioremediation of products from the oil sand and shale (e.g., Dilbit and Bakken oil). This can help evaluate the different aspects of hydrocarbon biodegradation and identify the knowledge gaps in the literature.

This paper deals with the complexities of crude oil geopolitics in the wake of recent escalating tensions between OPEC led by Saudi Arabia and OPEC plus members led by Russia. The paper traces the story of the Syrianic Dreams of global super powers in the Middle East and in the surrounds of the Caspian Sea prior to 1950s and afterwards. The paper proceeds to analyse the looming threat to the architecture of crude oil geopolitics in recent years caused by the decisive emergence of the US as the world’s largest oil producer since 2014 - a development that was entirely driven by galloping shale oil production in the country. It is argued that the shale oil shock has threatened the future of the OPEC and that of larger coalition bodies like OPEC+, that are led by Saudi Arabia and Russia respectively. As the world braces itself for a new oil price war in 2020, we take a look at what possible geopolitical configurations that could emerge from these extraordinary circumstances and the strategic elements surrounding crude oil pricing in the world. We also study the threat to the time tested instrument of petrodollars in the wake of increasing efforts to de-dollarize crude oil transactions through digital currency alternatives like the petro-yuan.

Understanding the transport mechanism of hydrocarbons through kerogen nanopores is crucial to shale oil production. However, existing studies primarily focus on single-component hydrocarbons; some important characteristics of shale kerogen were not thoroughly accounted for, such as the rough kerogen surface, the existence of heteroatoms, and the cylindrical pore geometry. We study the adsorption and pressure-driven flow behavior of multicomponent hydrocarbon mixtures through realistic shale kerogen nanopores. For the first time, we show that caused by the strong attraction from the kerogen substrate and its rough surface, hydrocarbons exhibit a parabolic velocity profile only in the central pore, and a sticky layer forms upon the kerogen surface. Our results contradict the fast mass transport reported in previous studies, in which ultrasmooth carbon nanotube or graphene was used to mimic shale kerogen. The existence of a sticky layer decreases the mobilized cross-sectional area of the kerogen pore, which dramatically impedes the transport capability of shale oil. Increasing the driving force or the proportions of light components will shrink the sticky layer and enhance fluid mobility. CO2 injection performs well in recovering the hydrocarbons of the sticky layers by reducing the thickness and viscosity. This study, which stresses the need for taking into account the realistic kerogen structure in future studies, sheds light on the exploitation of shale oil resources and, more generally, for mass transport in nanoporous materials.

The coupling effect of subcritical water and FeCl3 on the extraction of bulk Huadian oil shale was experimentally investigated. The results showed that, with the addition of FeCl3, the yield of shale oil in subcritical water extraction was enhanced by 58.5 % at 20 h and the time required for the maximum shale oil production was reduced by 43 %. The group compositions of shale oil and residual bitumen as well as the elemental analysis of residual kerogen revealed that FeCl3 could trigger the pyrolysis reaction networks of kerogen by promoting the cleavage of heteroatom bonds, and accelerate the decomposition of asphaltenes in residual bitumen. GC-MS analysis of n-alkanes in shale oil and residual bitumen showed that FeCl3 promoted the secondary cracking of saturated hydrocarbons in residual bitumen rather than in shale oil due to the adsorption of Fe3+ in shale matrix. The solid-state 13C NMR analysis of the residual kerogen indicated that the polycondensation of kerogen was inhibited and the ring-opening reaction of aromatic structure was promoted in the presence of FeCl3. In addition, the acidic FeCl3 solution induced the decomposition of carbonate minerals in oil shale matrix to provide additional mass transfer channels for the migration of bitumen products.

Oil and gas exploration and development have a long history and remain important in the American West. The region supported 150,000 well completions from 2000 to 2017. In the same timeframe, unconventional oil and gas development in the West’s Niobrara and Bakken formations contributed 28% of United States shale oil production and 14% of shale gas yields. This essay introduces the concept of “impact geography” as a guiding framework for synthesizing literature on social impacts of unconventional oil and gas development and deploys the concept in a review of recent published literature on social impacts in the region. The impact geography approach reflects the fact that that social impacts are generated by, and contingent upon, interactions between economic cycles, geology, technology and local context as they occur in particular spaces and places. This review of social impacts, broadly defined, is organized around three major impact geographies: rural and remote; (sub) urban; and sovereign nations. Within these geographies, we identify a variety of places—boomtowns, industrialized countrysides, borderlands, petro-suburbs, and focusing sites —and survey the impacts that stakeholders within them have experienced as they have been reported in the academic literature.

Extraordinary oil price declines were observed from 2008 to 2009 and from 2014 to 2016. During these periods, international oil prices collapsed by more than one half. Several reasons have been suggested for these crashes by numerous industry experts and scholars. In this study, we propose a new approach to explain the causes of the extreme oil price plummets via the supply and demand factors of price determinants. The autoregressive models with exogenous variables reflecting real demand, speculative demand, and supply factors are proposed and applied for forecasting monthly global crude oil prices during their periods of decline. Using the forecasting results, we retrospectively try to discover the factor that is best able to improve forecasting performance. During the first period of oil price decline, real demand reduction seemed to play a more prominent role compared with the other factors. Meanwhile, some supply factors, measured by U.S. shale oil production, combined with real and speculative demand factors, played an important role during the period of second oil price drop.

Currently, the conventional Fushun-type retorting process is the most main way of shale oil production in China. However, it has many disadvantages, such as low resource utilization efficiency and severe environmental pollution inevitably. In this paper, the framework of exergetic life cycle assessment (ELCA) is applied to the shale oil production process, and the indicator of resource utilization efficiency (γ) and the indicator of environmental sustainability (ζ) were defined to evaluate the performance of the resource utilization efficiency and environmental sustainability. The results indicate that the Aspen Plus simulation results are reasonably consistent with industrial data. The yield of shale oil is 4.52 kg/s by the pyrolysis of 100 kg/s oil shale. The framework of ELCA is applicable for the Fushun-type shale oil production process. During the whole life cycle, the cumulative exergy consumption (CExC) and the Abatement exergy (AbatEx) of pollutants (per kg shale oil produced) are 225.65 MJ and 61.69 MJ, respectively. The retorting stage has the lowest exergy efficiency, 62.49%, followed by the semi-coke gasification stage 63.15%. The γ and ζ values in shale oil production stage are very poor, 42.64% and 32.64%, respectively. When the retorting temperature is set to 500 °C and the saturation of feeding air is controlled to 80 °C, the γ and ζ values of the whole life cycle achieve the greatest potential, 35.85% and 28.05%, respectively.

Shale oil production has increased rapidly in the past decades, especially in the United States, and results in a revolution in the energy landscape. However, one main problem existing in the shale reservoir development is the sharp decline of liquids production in all the hydraulically fractured wells. In recent years, CO2 huff-n-puff injection has been proved to be a potential method to enhance the oil recovery. In this study, the effects of injection pressure and imbibition water on CO2 huff-n-puff performance were further investigated. Eagle Ford core samples and Wolfcamp dead oil were used in this experimental study. The microscopic pore characteristics of Eagle Ford shale core samples were analyzed, and the results show that 98.08% of the pore sizes are distributed between 3 nm and 50 nm. The experimental results demonstrate the great potential of CO2 huff-n-puff EOR. The cumulative oil recovery can reach 68% after seven huff-n-puff cycles. The oil recovered in each cycle deceases as injection cycle...

The rise and fall of shale oil production in recent years have led to tremendous economic growth and challenges to shale communities in the U.S. In this study, we attempt to address the inconsistent results in previous studies and shed light on the relationship between rural crimes and shale oil development at the Bakken using county‐level data for Montana and North Dakota from 2000 through 2014. Our results indicated statistically significant evidence of increased aggravated assaults, burglaries, larcenies, and motor vehicle thefts in shale‐oil producing counties during the boom. However, the regression results suggest that the rise in certain violent crime, such as murder, rape, and robbery, is not statistically attributable to the shale oil boom or oil activity, but to increased population in the two states. The crime effect of the boom also grew larger especially after 2008. The results point to some evidence of social disruption in rural communities undergoing rapid shale oil development. More importantly, the Bakken's crime experience also suggests a number of critical needs for shale energy regions nationwide.

Huadian oil shale was subjected to step-wise acid treatment to remove inherent carbonate and silicate minerals. The original oil shale and its demineralization products (carbonate- and carbonate-silicate-free oil shale samples) were pyrolyzed in a fixed-bed pyrolyzer to determine the mineral matrix effect on product yield and characteristics of shale oil and gases. The shale oil yields of original, carbonate-free, and carbonate-silicate-free oil shale samples were 50.4 wt.%, 44.3 wt.%, and 50.3 wt.% (values on dry and mineral matter-free basis), respectively, which indicated that carbonates promote, while silicates suppress, shale oil production. Coking of aromatic compounds appeared to be the dominant mechanism accounting for the variation of the shale oil yield. Elimination of the carbonate minerals decreased the nitrogen- and oxygen-containing compounds of shale oil, while removal of silicates increased the oxygenated compounds. Both carbonate and silicate minerals decreased the atomic H/C ratio of shale oil. Silicates promoted the cracking and aromatization of aliphatic hydrocarbons, which increased the short-chain aliphatic hydrocarbons and aromatic hydrocarbons of shale oil, as well as C1–C4 hydrocarbons and H2 yields. On the contrary, carbonates suppressed the cracking of long chain aliphatic hydrocarbons.

In view of the importance and complexity of international crude oil price, this paper proposes a novel combination forecast approach that captures a variety of fluctuation features in crude oil data series, including change points, regime-switching, time-varying determinants, trend decomposition of high-frequency sequences, and the possible nonlinearity of model setting. First, product partition model-K-means (PPM-KM) model is used to detect change points in the oil price sequence. Next, we apply a time-varying transition probability Markov regime switching (TVTP-MRS) model to identify the regime-switching characteristic. Then, we use Bayesian model averaging (BMA) to filtrate main determinants at each regime. Finally, the time-varying parameter structure time series model (TVP-STSM) is used to decompose the oil sequence, capture the time-variation of coefficients in “volatile upward” regime, and forecast the crude oil price. Compared with some other competing models and benchmark model of ARIMA, the newly proposed method shows superior forecasting ability in four statistical tests. Besides, we make scenario prediction on WTI crude oil price to examine the implementation effect of OPEC cut-off agreement at the end of 2016. OPEC production and U.S. shale oil production are used as two scenario variables, and the WTI price is forecasted fluctuating around 50 dollar/barrel based on three scenario prediction. We conclude that WTI crude oil price would take a shock upstream tendency in the short-term but the rising scope would not be large.

Experiments on co-combustion of oil shale and its semi-coke were conducted in a lab-scale bubbling fluidized bed. Oil shale blend ratios from 0 to 100% at the interval of 25% were separately tested at 800, 850 and 900 °C, to clarify combustion behaviors and pollutant emission characteristics. Results indicated that as oil shale mass fraction increased, the combustion efficiency of samples firstly increased, and then decreased. Positive synergistic relationships between oil shale and its semi-coke were identified. The addition of oil shale could help reducing the SO2 emissions during co-combustion, while the NO emissions showed no significant change. Meanwhile, with temperature rising, the CO concentrations of samples with lower oil shale blend ratios (0, 25% and 50%) slightly decreased, on the contrary, for higher oil shale blend ratios (75% and 100%), the CO concentrations increased, however, the SO2 and NO concentrations got a monotonic increase for all the samples. Hence, from the view point of combustion efficiency and pollutant emission performances, it was recommended that the oil shale blend ratio was 50% and the bed temperature was about 800 °C. Besides, the ultra-low emission of SO2 and NO emitted from the co-combustion of oil shale and semi-coke were able to be achieved by adopting appropriate pollutant control measures.

Shale oil production is considered to be one of the important determinants of oil price slump in 2014-2016. According to some experts, shale oil became a new market "regulator", ousted OPEC. Shale oil production is characterized by non-trivial dynamics. After an accelerated growth in 2010-2015, a period of fluctuations in production caused by the volatility of oil prices followed. The paper develops approach to the shale production modelling on the base of the analytical solutions of differential equation with retarded argument. The differential equation reflects the fact that production change consists of a sum of new debits and the natural process of base production decline. Besides, possibilities of origination and prerequisites of endogenous economic oscillations of shale oil production are studied. Calculations, implemented for economic and technological characteristics given for period from December 2014 to May 2017, showed a possibility of existence of oil production oscillation with period of 33 month, that does not contradict to observations. In general, the proposed approach can be used as a nonlinear structural method for forecasting oil production and corresponding price component, connected with production change.

This study reviews the mechanism of microwave irradiation and the affecting parameters, including heating rate, particle size, catalysts, and supercritical fluids on the microwave induced pyrolysis of oil shales. The factors influencing shale oil upgrading using microwave and conventional heating were analyzed. Although shale ash induces secondary cracking in conventional heating, followed by cracking of heavy compounds and increased light oil and pyrolysis gas, the corresponding mechanism in microwave heating has not yet been studied. The shale ash composition and particle size play a vital role in conventional heating efficiency. Increasing oil shale particles size in conventional heating after reaching the maximum converted shale oil reduces produced oil due to increased heat transfer and volatile diffusion in oil shale grains and induction of secondary cracking, which leads to the intensification of shale oil upgrading. Catalysts with high microwave absorption capacity, such as iron powder, remove higher percentages of sulfur, nitrogen, and oxygen from shale oil in microwave pyrolysis as compared to conventional heating. The presence of zeolite in microwave pyrolysis causes better and more effective shale oil upgrading by reducing C10-C16, >C16, naphtha fraction, and increasing kerosene fraction compared to conventional pyrolysis. The presence of water increases polycyclic aromatics, increases the concentration of alkene fraction and decreases asphaltene and coke formed by solvation or caging of shale oil molecules. The presence of nitrogen and hydrogen in conventional pyrolysis reduces desulfurization and upgraded shale oil yield, respectively. A sharp increase in the heating rate in conventional and microwave pyrolysis reduces shale oil yield. In conventional heating, increasing heating rate decreases the hydrogen (H)/ carbon (C) ratio, and the nitrogen and sulfur fractions increase due to the nature of chemical bonding with hydrocarbons and its entangled with metal oxides. In microwave pyrolysis at high heating rates, the H/C ratio increases and the amounts of nitrogen and sulfur in shale oil decrease sharply. The high microwave radiation power facilitates the removal of nitrogen and sulfur that is much higher than conventional pyrolysis. The conversion of pyrite to pyrrhotite in oil shales that have a high microwave absorption capacity increases microwave pyrolysis efficiency. The calcite and feldspar also improve this process because they participate in the pyrolysis process, and their amounts are reduced in the spent shale. Thus, the oil produced from oil shales under the microwave pyrolysis process has lighter and higher quality compounds. However, the broad applications of this technology in the use of oil shales are still unclear and more studies should be done to clarify the advantages and disadvantages of using microwave heating in oil shales. Further study and research are required to develop microwave technology in oil shale, and based on its potentials, it can be introduced as a new and efficient method in oil shale production.

Waste shipping oil, a mixture of used lubricating oil and seawater derived from ship engine operation, was tested for its potential to be converted into a fuel product via an innovative microwave-assisted pyrolysis approach using a reaction bed of activated carbon. Higher carbon to waste ratio was found to have beneficial effects in promoting pyrolysis cracking to produce a higher yield of pyrolysis oil, recording a yield of up to 66 wt%. The pyrolysis oil comprised of aliphatic hydrocarbons (C5–C15 hydrocarbons) that are within the hydrocarbon range for gasoline and diesel. Combined with the detection of low viscosity (2 − 5 mm2/s) and high calorific value (46 MJ/kg) nearly comparable to diesel, the pyrolysis oil shows potential to be upgraded to diesel fuel. The oil product was also detected to have low contents of oxygen (0.1 wt%) and sulphur (0.02 wt%), showing promising features as a ‘cleaner’ fuel source with potentially reduced formation of tar (an oxygenated byproduct) and low emission of SOx during the use of the oil as fuel in combustion process. Our results indicate that microwave-assisted pyrolysis shows potential as an alternative to transform waste shipping oil into an alternative fuel source.

Based on the observation of the well cores, thin section and FESEM, combined with X-ray diffraction, physical property testing and geochemical indicators, the reservoir characteristics and the controlling factors of the shale oil enrichment of the Ess 4–Esx 3 shale in the Jiyang depression were detailed analyzed. Studies show that carbonate and clay minerals are dominated in the shale. According to the triangle chart, the TOC content (2% and 4%), carbonate and clay minerals, nine lithofacies have been identified. The reservoir space types are rich in the shale, in which, the laminated fractures, recrystallization intracrystalline pores and organic pores are high-quality reservoir spaces. The shale oil enrichment is mainly determined by the hydrocarbon-producing potential and reservoir capacity. The hydrocarbon- producing capacity is controlled by the organic geochemistry indicators, especially the TOC content for the study area, and the thickness of the organic-rich shale. The reservoir capacity is mainly affected by the lithofacies, the TOC content and the structural activities. In addition, the shale oil production is influenced by the fracability of the shale, which is mainly controlled by the lithofacies, structural activities, formation pressure, etc. The shale oil reservoir evaluation should focus on the TOC content, the thickness of the organic-rich shale, lithofacies and structural factor.

The aim of this paper is to relate the shale oil revolution in the United States with WTI oil price behavior. Since the development of the combination of horizontal drilling techniques together with hydraulic fracturing in the 1970s, known as shale oil, oil markets have undergone a significant transformation with the unexpectedly strong rise in the United States production affecting oil prices. The goal of this paper is two-fold: first, we analyze the relationship of total United States crude oil production and WTI crude oil prices by studying its performance in the time-frequency domain applying wavelet tools for its resolution. Using wavelet methodologies, we observe a shift to higher frequencies of the wavelet coherency for the time period 2003–2009 and lower frequencies for the period 2009–2014. The results also indicate that during the period 2003–2009 the U.S. oil production and WTI oil prices time series are in phase; they move together, with total United States oil production leading. During the period 2009–2014 oil production and WTI oil prices time series are out of phase (negatively correlated), suggesting that oil production increases precede a decrease in WTI oil prices. In the second part of the paper and to give greater credibility to the results obtained through the wavelet transform, we analyze the behavior of WTI crude oil before and after the shale oil boom in the United States employing methodologies based on long run dependence. The results indicate that mean reversion takes place only for the data corresponding to the first subsample, ending at 2003. For the second subsample, as well as for the whole sample, lack of mean reversion is detected with orders of integration equal to or higher than 1 in all cases.

Fracture has a vital effect on the storage and seepage ability of oil and gas in shale reservoirs, and its effective identification and evaluation is of great significance for shale oil and gas development. To analyze and evaluate fracture development characteristics in the lower sub-member of the third member of the Eocene Shahejie Formation (Es3L) and the upper sub-member of the fourth member of the Eocene Shahejie Formation (Es4U) in the Jiyang Depression, Bohai Bay Basin, core observations, thin sections, field emission scanning electron microscopy (FE-SEM), and well logging were performed. After data analysis, fracture types in the study area were characterized, relationships between shale oil types and shale oil production were discussed, and a new method was proposed to identify fractures using only conventional logging curves by combining discrete wavelet transform (DWT) and box fractal dimension with sliding window approach (SW box fractal dimension). Our results indicated that the fracture types according to geologic genesis are structural fractures (structural tension fractures, structural shear fractures, and structural tension-shear fractures), non-structural fractures (abnormal pressure fractures, diagenetic contraction fractures, bedding fractures, and dissolution fractures), and organic matter-related fractures. A close relationship occurs involving the types of shale oil and shale oil production, and fractured shale oil usually has the highest initial production. The fracture identification method using the DWT and SW box fractal dimension has good effects, and its accuracy is verified by Fullbore Formation MicroImager (FMI) logging in L69 well. Two high-production wells of shale oil in the study area (wells FY1 and Y187) were used to identify fracture development sections using the DWT and SW box fractal dimension, and excellent application results were obtained. In general, it is an efficient way to fully evaluate fracture development sections in shale reservoirs in logging profiles, and also provides new ideas for the fracture identification method using conventional logging curves in other shale oil regions.