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Fossil fuels, such as coal and hydrocarbons, are major drivers of global warming and are primarily responsible for worldwide greenhouse gas emissions, including carbon dioxide CO2. The storage of CO2 in deep saline reservoirs is acknowledged as one of the top practical and promising methods to reduce CO2 emissions and meet climate goals. The North Dakota Industrial Commission (NDIC) recently approved the fourth Class VI permit for a carbon capture and storage project in the Williston basin of North Dakota for the geological CO2 storage in the Broom Creek formation. The current research aimed to conduct a comprehensive petrophysical characterization and rock physics modeling of the Broom Creek deep saline reservoir to unravel the mineralogical distribution and to understand the variations in petrophysical and elastic properties across the formation. This study utilized geophysical well logs, routine core analysis, and advanced core analysis to evaluate the Broom Creek formation. Multimineral petrophysical analysis calibrated with X-ray diffraction results reveals that this formation primarily comprises highly porous clean sandstone intervals with low-porosity interspersed with dolomite, anhydrite, and silt/clay layers. The formation exhibits varying porosities up to 0.3 and Klinkenberg air permeabilities up to ∼2600 mD. The formation water resistivity using Archie’s equation is approximately 0.055 ohm-m at 150 °F, corresponding to around 63,000 ppm NaCl salinity, which is consistent with prior data. The pore throat distribution in the samples from clean sandstone intervals is primarily situated in the macro-mega scales. However, the presence of anhydrite and dolomite impedes both porosity and pore throat sizes. The accurate prediction of effective elastic properties was achieved by developing a rock physics template. Dry rock moduli were modeled using Hill’s average, while Berryman’s self-consistent scheme was employed for modeling saturated moduli.

The growing popularity of unconventional wells has led to increased interest in assessing and predicting their production performance. These wells, with their extended-reach structures, are able to generate and access larger reservoir volumes. Therefore, understanding the impact of a well’s lateral trajectory on its transient production performance is crucial. This study investigates the effect of lateral-trajectory undulation amplitude on flow behavior based on the experimental results obtained at the University of North Dakota using an undulated two-phase (UTP) flow loop. The experiments involved injecting an air-and-water mixture through a section with variable undulation amplitude followed by a vertical section. The results revealed that the increasing undulation amplitude resulted in lower translational velocity, frequency, and length, with consistent slug acceleration along the system profile. Additionally, the frequency of slugs decreased as they traveled through the vertical section. The measured data indicated that higher undulation amplitudes led to increased horizontal pressure losses and variability, suggesting larger instabilities. The numerical simulations predicted lower translational velocity and frequency, longer slug length, and similar vertical pressure losses when compared to the experimental results.

The net-effective stress is a fundamental physical property that undergoes dynamic changes in response to variations in pore pressure during production and injection activities. Petrophysical properties, including porosity, permeability, and wave velocities, play a critical role and exhibit strong dependence on the mechanical stress state of the formation. The Williston basin’s Bakken Formation represents a significant reservoir of hydrocarbons within the United States. To investigate this formation, we extracted core plugs from three distinct Bakken members, namely Upper Bakken, Middle Bakken, and Lower Bakken. Subsequently, we conducted a series of measurements of ultrasonic compressional and shear wave velocities, as well as pulse decay permeabilities using nitrogen, under various confining pressures employing the Autolab-1500 apparatus. Our experimental observations revealed that the ultrasonic wave velocities and permeability display a significant sensitivity to stress changes. We investigated existing empirical relationships on velocity-effective stress, compressional-shear wave velocities, and permeability-effective stress, and proposed the best models and associated fitting parameters applicable to the current datasets. In conjunction with the acquired datasets, these models have considerable potential for use in time-lapse seismic monitoring and the study of production decline behavior. The best fitting models can be used to forecast the petrophysical and geomechanical property changes as the reservoir pore pressure is depleted due to the production, which is critical to the production forecast for unconventional reservoirs.

Although considerable laboratory and modeling activities were performed to investigate the enhanced oil recovery (EOR) mechanisms and potential in unconventional reservoirs, only limited research has been reported to investigate actual EOR implementations and their surveillance in fields. Eleven EOR pilot tests that used CO2, rich gas, surfactant, water, etc., have been conducted in the Bakken unconventional play since 2008. Gas injection was involved in eight of these pilots with huff ‘n’ puff, flooding, and injectivity operations. Surveillance data, including daily production/injection rates, bottomhole injection pressure, gas composition, well logs, and tracer testing, were collected from these tests to generate time-series plots or analytics that can inform operators of downhole conditions. A technical review showed that pressure buildup, conformance issues, and timely gas breakthrough detection were some of the main challenges because of the interconnected fractures between injection and offset wells. The latest operation of co-injecting gas, water, and surfactant through the same injection well showed that these challenges could be mitigated by careful EOR design and continuous reservoir monitoring. Reservoir simulation and machine learning were then conducted for operators to rapidly predict EOR performance and take control actions to improve EOR outcomes in unconventional reservoirs.

Flow assurance has been a major challenge in petroleum production systems especially in offshore operations where severe slugging is a dominant aching issue. This is characterized by pulsating flow behavior which impacts the reservoir productivity, pipeline-riser systems, and surface facilities (separator). The only means so far, of delivering reservoir fluids from offshore wells to the separator at the surface is by pipeline-riser systems where slugging is most prominent and oftentimes unavoidable. Though passive and active measures have been deployed over time to mitigate the associated problem, there is the need to develop a predictive tool for mitigating offshore slugging in the riser system. This study involves the use of a model and analysis approach to eliminate severe slugging based on the balance of forces acting on the pipeline-riser system. Modified stability criteria which consider accumulation and frictional pressure drops have been developed. The current approach is solely physicsdriven, to predict the corresponding liquid and gas velocities at which the fluctuations would be severe when producing multiphase fluids through pipeline-riser systems. By balancing the forces acting on a riser-pipeline system and accounting for frictional and accumulation effects, two hydraulic flow modeling approaches have been used in this study to improve the criteria for predicting the condition of severe slugging. The developed criteria were computed using MATLAB/Simulink and a severe slugging flow map was generated. The “new study 1” and “new study 2” showed a 16% and 13% increase respectively in predicted unstable cases than the Malekzadeh criteria. The criteria were tested at different separator pressures. The Taitel and Jansen criteria could not predict severe slugging at elevated separator pressure. Notwithstanding, the developed flow maps using the “new study 1” are more reliable than the “new study 2”. This is because the “new study 2” approach over defines the physics of severe slugging. The criteria were also tested at varying accumulation times. This was done by step increments in the order of magnitude of time. The separator pressure affects the optimal time for modeling the accumulation at the riser-base. The criteria are therefore useful for predicting optimal operating conditions for flow assurance for the pipeline-riser system in consideration.

To achieve the Net Zero Carbon Emissions (NZCE) target by 2050, Carbon Capture, Utilization, and Storage (CCUS) is a major method. Gathering and injecting CO2 into shale reservoirs is an effective way to reduce the CO2 amount in the air and thus, release the greenhouse effect. CO2 injection into organic-rich shales could provide dual benefits of incremental oil or gas recovery and secure CO2 storage. When planning the CO2 injection project, the most important question is how much gas could be stored in the reservoir. Methods for calculating CO2 storage potential in shale reservoirs have been studied by many researchers. However, few researchers put those methods together and make comparisons to each other. This paper summarized five methods for evaluating CO2 storage potential in five shale reservoirs by using the literature published in recent years. This paper aims to discuss and evaluate the technical aspects related to gas storage. Those geomechanical properties, petrophysical properties, and construction parameters were discussed. Among those parameters, CO2 injection rate, skin factor, and Knudsen diffusion could significantly affect CO2 storage potential evaluation results. Also, if well integrity, especially cement quality, and permeability could be taken into consideration, CO2 storage simulation models' results will be more realistic. The significances of this study are: (1) served as guidance in calculating CO2 storage capacity in shale oil plays; (2) provides analyses in evaluating nowadays methods’ limitations; (3) gives recommendations to researchers on how to improve those methods or create a new one.

The present work intended to develop an invert emulsion drilling mud from biodegradable neem seed oil as an alternative to conventional diesel-based drilling mud. This would present comparable properties and performances with API standard requirements, ecologically friendly and at a low cost. Biodiesel produced from non-edible neem oil was used as the continuous phase in an invert emulsion-based drilling mud. Different tests to investigate the applicability of the mud for drilling applications were conducted. The rheological and lubricity tests results indicate that the neem oil biodiesel-based drilling muds are comparable with conventional diesel-based drilling muds. The produced biodiesel shows a significantly better flash point of 168 °C than the traditional diesel flash point of 70 °C; indicating better fire safety than the conventional diesel. The lubricity and rheological data indicate the formulated mud with neem seed oil biodiesel fair reasonably well with conventional diesel and within the API requirements. In general, the preliminary results show that neem oil biodiesel is a potential alternative to conventional organic oil in formulating oil-based drilling mud in terms of technical and environmental analysis.

AbstractWith the development of high-pressure and high-temperature condensate gas wells, the wellbore blockage problems have become increasingly serious. Hence, selecting appropriate treatment technology plays a crucial role in solving the wellbore blockage problems. This study presents a comprehensive literature review on understanding the blockage type, mechanism, and treatment of the high-temperature and high-pressure condensate gas wells. The causes, endangerments, mechanisms, influences, and preventive technologies of the 4 wellbore blockage types are presented. The significant aspects of the treatment technology, such as the principle, type, advantage and disadvantage, adaptability, limitation, and future research direction of the treatment technologies, are thoroughly discussed. The breakthrough solid autogenetic heat treatment technology has been selected to remove hydrate blockage. The present review highlights the current state in the industry, future position, and strategies for the researchers to follow. Finally, the advantages and disadvantages and future research directions of specific treatment technology are presented on the removing effect, cost, and environmental aspects.

Parallel pipelines are widely used to transport energy resources. Leakages usually can occur in pipelines due to aging, corrosion, metal failure, etc. When an accident happened, not only the energy company would take the financial loss, but also it would cause pollution and safety issues to the local environment. Therefore, an efficient way to identify leakages in parallel pipelines is necessary to be proposed. In this study, ANSYS was used to simulate different leak scenarios in parallel pipelines. Fluid and pipe parameters were used to simulate different leak scenarios. In each leak scenario, there were different pressure drops along the leak pipeline based on leak locations and different flow rates. After determining there is more than a leak in pipelines, the relationship among pressure drops, leak locations, and flow rates can be used to build a mathematical model for detecting leaks. During the pipeline operations, the pressure drops were affected by leak locations and flow rates. Therefore, applying flow parameters in real leak scenarios to the mathematical model that is built from the parameters in the reality will identify the leak locations. In addition, lab experiments were applied to verify the validity of the simulations. The deviations between the experiments and simulations are less than 4%. The pressure drops through the leak pipe in the experiments and simulation vary from 1,955 to 2,898 Pa and 1,992 to 2,803 Pa, respectively. This research investigated a method to identify two-point leakages in parallel pipelines based on flow parameter analysis.

Recovery efficiency is a key factor in decision-making in oil and gas projects. Although structural setup and well type considerably influence waterflood recovery, few studies have explored the performance of highly deviated wells during the waterflooding of complex shallow reservoirs. Here, we applied numerical simulations to investigate the performance of vertical, horizontal, multilateral, and highly deviated wells during waterflooding of complex shallow reservoirs using the J1 Oilfield as a case study. Recovery efficiencies of 31%, 33%, 31%, and 26% could be achieved for vertical, horizontal, multilateral, and highly deviated wells, respectively. The gas production rate was 39% higher in the vertical wells than in the other types. Highly deviated wells yielded the highest water-cut (80%) over a short period. Highly deviated wells delivered the least production, and, despite branching laterals, multilateral wells were also not the most productive. Our results provide insights into the performance of different well types during the waterflooding of green heterogeneous non-communicating reservoirs and present an example of the successful practical application of waterflooding as an initial recovery mechanism when oil is near the bubble point. This study indicated that multilateral wells are not a panacea in reservoir development. Highly deviated wells are the ideal choice for the shallow, heterogeneous non-communicating reservoirs when economic and environmental impact are considered in decision-making. Well design should be a case-by-case study considering reservoir characteristics, economics, and environment impact.

The low recovery of oil from tight liquid-rich formations is still a major challenge for a tight reservoir. Thus, supercritical CO2 flooding was proposed as an immense potential recovery method for production improvement. While up to date, there have been few studies to account for the formation properties’ variation during the CO2 Enhanced Oil Recovery (EOR) process, especially investigation at the micro-scale. This work conducted a series of measurements to evaluate the rock mechanical change, mineral alteration and the pore structure properties’ variation through the supercritical CO2 (Sc-CO2) injection process. Corresponding to the time variation (0 days, 10 days, 20 days, 30 days and 40 days), the rock mechanical properties were analyzed properly through the nano-indentation test, and the mineralogical alterations were quantified through X-ray diffraction (XRD). In addition, pore structures of the samples were measured through the low-temperature N2 adsorption tests. The results showed that, after Sc-CO2 injection, Young’s modulus of the samples decreases. The nitrogen adsorption results demonstrated that, after the CO2 injection, the mesopore volume of the sample would change as well as the specific Brunauer–Emmett–Teller (BET) surface area which could be aroused from the chemical reactions between the CO2 and some authigenic minerals. XRD analysis results also indicated that mesopore were altered due to the chemical reaction between the injected Sc-CO2 and the minerals.

The efficacy of gaseous solvents in enhancing oil recovery (EOR) in unconventional reservoirs and the influence of operational and design parameters are still debated among the oil recovery research community. This work investigated the recovery-enhancing capabilities of two potent gaseous solvents, CO² and ethane, in tight core samples. Laboratory huff-n-puff (H-n-P) experiments were conducted under three miscibility conditions to investigate the influence of the key operating parameters and the dependency of their impact on the miscibility conditions and gas composition. The results show that oil recovery increased with increasing pressure from below (BM) to above (AM) miscibility pressure in a non-linear trend, irrespective of the gas composition. Furthermore, the influence of the soak period was noticeably dependent on the miscibility condition, specifically more remarkable under AM conditions and less apparent under BM conditions. Likewise, the effect of the production period was more pronounced at AM conditions for both gases. Finally, the impact of rock surface area-to-volume (SA/V) was only observed at BM, where both gases recovered more oil in the core samples with high SA/V. In general, ethane showed a higher efficacy for oil recovery than CO2; CO2 recovered 21%e70% of oil in small core samples, while ethane could recover 32%e88%. The highest recovery was achieved with ethane injected under AM conditions, with a prolonged soak time, a short production period and into a core sample with a high SA/V. We believe the findings from this work will help better understand and design H-n-P EOR projects. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is an inflammatory disease accompanied by abnormal synovial microenvironment (SM). Sesquiterpene lactones (SLs) are the main anti-inflammatory ingredients of many traditional herbs utilized in RA treatment. α-Methylene-γ-butyrolactone (α-M-γ-B) is a core moiety that widely exists in natural SLs. This study was designed to investigate the anti-arthritic potential of α-M-γ-B as an independent small molecule in vitro and in vivo. α-M-γ-B exhibited stronger electrophilicity and anti-inflammatory effects than the other six analogs. α-M-γ-B inhibited the production of pro-inflammatory mediators via repolarizing M1 macrophages into M2 macrophages. The transcriptome sequencing suggested that α-M-γ-B regulated the immune system pathway. Consistently, α-M-γ-B attenuated collagen type II-induced arthritic (CIA) phenotype, restored the balance of Tregs-macrophages and remodeled SM via repolarizing the synovial-associated macrophages in CIA mice. Mechanistically, although α-M-γ-B did not prevent the trans-nucleus of NF-κB it interfered with the DNA binding activity of NF-κB via direct interaction with the sulfhydryl in cysteine residue of NF-κB p65, which blocked the activation of NF-κB. Inhibition of NF-κB reduced the M1 polarization of macrophage and suppressed the synovial hyperplasia and angiogenesis. α-M-γ-B failed to ameliorate CIA in the presence of N-acetylcysteine or when the mice were subjected to the macrophage-specific deficiency of Rela. In conclusion, α-M-γ-B significantly attenuated the CIA phenotype by directly targeting NF-κB p65 and inhibiting its DNA binding ability. These results suggest that α-M-γ-B has the potential to serve as an alternative candidate for treating RA. The greater electrophilicity of α-M-γ-B, the basis for triggering strong anti-inflammatory activity, accounts for the reason why α-M-γ-B is evolutionarily conserved in the SLs by medical plants.

Abstract Background Siegesbeckia pubescens Makino (SP) is one of the important plant origins for the anti-inflammatory Chinese herbal medicine of Siegesbeckiae Herba. The current investigations indicated that the anti-inflammatory effects of SP were associated with the toll-like receptors (TLRs)-mediated nuclear factor-κB (NF-κB) and the mitogen-activated protein kinase (MAPK) signaling pathways. Methods Raw 264.7 macrophages were pretreated with the 50% ethanol extract of SP (SPE, 50–200 µg/mL) and then co-treated with Pam3CSK4 (200 ng/mL) for another 12 h. The inhibitory effect of SPE on Pam3CSK4-stimulated NO release and post-inflammatory cytokines secretions were determined using Griess reagent and Elisa kits, respectively. The influence of SPE on NF-κB and MAPKs signaling relevant proteins was measured by Western blotting analysis, while the intracellular nitric oxide (NO) generation and NF-κB/p65 nuclear translocation were determined using Leica TCS SP8 laser scanning confocal microscope. Moreover, the effect of SPE on luciferase reporter gene in NF-κB-luc DNA transfected raw 264.7 cells was determined using the Dual-Glo luciferase assay system kit. Results SPE dose-dependently (50–200 µg/mL) attenuated Pam3CSK4-induced NO release, post-inflammatory cytokines (IL-6, TNF-α and MCP-1) secretions and intracellular NO generation in raw 264.7 cells. Biologically, SPE suppressed Pam3CSK4-induced expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), phosphorylation of NF-κB/p65 and IκBα, but did not significantly show effect on the proteins involved in MAPKs signaling (p38, ERK and JNK). The results were further confirmed by NF-κB-luc reporter gene assay and p65 nuclear translocation assay. Conclusions In conclusion, SPE ameliorated Pam3CSK4-induced inflammation in raw 264.7 cells through suppressing TLR 1/2-mediated NF-κB activation.