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The process of “hysteresis” has widely attracted the attention of researchers and investigators due to its usage in many disciplines of science and engineering. Economics, physics, chemistry, electrical, mechanical, and petroleum engineering are some examples of disciplines that encounter hysteresis. However, the meaning of hysteresis varies from one field to another, and therefore, many definitions occur for this phenomenon depending on the area of interest. The “hysteresis” phenomenon in petroleum engineering has gained the attention of researchers and investigators lately, because of the role that plays in reservoir engineering and reservoir simulation. Hysteretic effects influence reservoir performance. Therefore, an accurate estimation of rock and fluid property curves has an essential role in evaluating hydrocarbon recovery processes. In this paper, a comprehensive review of research and growth on the hysteresis of wettability for its applications in petroleum engineering is reported. Also, theoretical and experimental investigations of hysteresis of wettability are compared and discussed in detail. The review highlights a range of concepts in existing models and experimental processes for wettability hysteresis. Furthermore, this paper tracks the current development of hysteresis and provides insight for future trends in the research. Finally, it reveals an outlook on the research challenges and weaknesses of hysteresis of wettability.

Oil production forecasting is an important task to manage petroleum reservoirs operations. In this study, a developed time series forecasting model is proposed for oil production using a new improved version of the adaptive neuro-fuzzy inference system (ANFIS). This model is improved by using an optimization algorithm, the slime mould algorithm (SMA). The SMA is a new algorithm that is applied for solving different optimization tasks. However, its search mechanism suffers from some limitations, for example, trapping at local optima. Thus, we modify the SMA using an intelligence search technique called opposition-based learning (OLB). The developed model, ANFIS-SMAOLB, is evaluated with different real-world oil production data collected from two oilfields in two different countries, Masila oilfield (Yemen) and Tahe oilfield (China). Furthermore, the evaluation of this model is considered with extensive comparisons to several methods, using several evaluation measures. The outcomes assessed the high ability of the developed ANFIS-SMAOLB as an efficient time series forecasting model that showed significant performance.

The current commercial technologies used to produce heavy oils and bitumen are carbon-, energy-, and wastewater-intensive. These make them to be out of line with the global efforts of decarbonisation. Alternative processes such as the toe-to-heel air injection (THAI) that works as an in situ combustion process that uses horizontal producer well to recover partially upgraded oil from heavy oils and bitumen reservoirs are needed. However, THAI is yet to be technically and economically well proven despite pilot and semi-commercial operations. Some studies concluded using field data that THAI is a low-oil-production-rate process. However, no study has thoroughly investigated the simultaneous effects of start-up methods and wells configuration on both the short and long terms stability, sustainability, and profitability of the process. Using THAI validated model, three models having a horizontal producer well arranged in staggered line drive with the injector wells are simulated using CMG STARS. Model A has two vertical injectors via which steam was used for pre-ignition heating, and models B and C each has a horizontal injector via which electrical heater and steam were respectively used for pre-ignition heating. It is found that during start-up, ultimately, steam injection instead of electrical heating should be used for the pre-ignition heating. Clearly, it is shown that model A has higher oil production rates after the increase in air flux and also has a higher cumulative oil recovery of 2350 cm3 which is greater than those of models B and C by 9.6% and 4.3% respectively. Thus, it can be concluded that for long-term projects, model A settings and wells configuration should be used. Although it is now discovered that the peak temperature cannot in all settings tell how healthy a combustion front is, it has revealed that model A does indeed have far more stable, safer, and efficient combustion front burning quality and propagation due to the maintenance of very high peak temperatures of mostly greater than 600 °C and very low concentrations of produced oxygen of lower than 0.4 mol% compared to up to 2.75 mol% in model C and 1 mol% in model B. Conclusively, since drilling of, and achieving uniform air distribution in horizontal injector (HI) well in actual field reservoir are costly and impracticable at the moment, and that electrical heating will require unphysically long time before mobilised fluids reach the HP well as heat transfer is mainly by conduction, these findings have shown decisively that the easy-and-cheaper-to-drill two vertical injector wells configured in a staggered line drive pattern with the horizontal producer should be used, and steam is thus to be used for pre-ignition heating.

Heavy oils and bitumen are indispensable resources for a turbulent-free transition to a decarbonized global energy and economic system. This is because according to the analysis of the International Energy Agency’s 2020 estimates, the world requires up to 770 billion barrels of oil from now to year 2040. However, BP’s 2020 statistical review of world energy has shown that the global total reserves of the cheap-to-produce conventional oil are roughly only 520.2 billion barrels. This implies that the huge reserves of the practically unexploited difficult-and-costly-to-upgrade-and-produce heavy oils and bitumen must be immediately developed using advanced upgrading and extraction technologies which have greener credentials. Furthermore, in accordance with climate change mitigation strategies and to efficiently develop the heavy oils and bitumen resources, producers would like to maximize their upgrading within the reservoirs by using energy-efficient and environmentally friendly technologies such as the yet-to-be-fully-understood THAI-CAPRI process. The THAI-CAPRI process uses in situ combustion and in situ catalytic reactions to produce high-quality oil from heavy oils and bitumen reservoirs. However, prolonging catalyst life and effectiveness and maximizing catalytic reactions are a major challenge in the THAI-CAPRI process. Therefore, in this work, the first ever-detailed investigations of the effects of alumina-supported cobalt oxide–molybdenum oxide (CoMo/γ-Al2O3) catalyst packing porosity on the performance of the THAI-CAPRI process are performed through numerical simulations using CMG STARS. The key findings in this study include: the larger the catalyst packing porosity, the higher the accessible surface area for the mobilized oil to reach the inner coke-uncoated catalysts and thus the higher the API gravity and quality of the produced oil, which clearly indicated that sulphur and nitrogen heteroatoms were catalytically removed and replaced with hydrogen. Over the 290 min of combustion period, slightly more oil (i.e. an additional 0.43% oil originally in place (OOIP)) is recovered in the model which has the higher catalyst packing porosity. In other words, there is a cumulative oil production of 2330 cm3 when the catalyst packing porosity is 56% versus a cumulative oil production of 2300 cm3 in the model whose catalyst packing porosity is 45%. The larger the catalyst packing porosity, the lower the mass and thus cost of the catalyst required per m3 of annular space around the horizontal producer well. The peak temperature and the very small amount of produced oxygen are only marginally affected by the catalyst packing porosity, thereby implying that the extents of the combustion and thermal cracking reactions are respectively the same in both models. Thus, the higher upgrading achieved in the model whose catalyst packing porosity is 56% is purely due to the fact that the extent of the catalytic reactions in the model is larger than those in the model whose catalyst packing porosity is 45%.

The need for efficient demulsification process to treat emulsions in the petroleum industry is well acknowledged. For decades, numerous researches have been conducted to examine mechanisms of emulsification and demulsification. Untreated emulsion has both technical and commercial implications in the industry, especially in terms of treatment facilities, refining and transportation. Effective treatment is needed to ensure optimum production of hydrocarbons. The present paper is to review reported works on the formation of petroleum emulsions, demulsification treatments, characteristics of fit-for-purpose demulsifiers as well as research trends in emulsion treatment. Crude oils are naturally combined with natural surfactants having high tendency to form stable emulsion. The stable emulsion must be treated well to meet industrial requirements since crudes with a high volume of stable emulsion have a less value. Therefore, fundamental studies on natural surfactants, which contribute to the emulsion stability, are analyzed for the effective separation of emulsions into oil and water. This would involve the assessment of various reported mechanisms for the emulsification and right formulation for effective demulsification.

There exist numerous counts of research works on produced water. We got to know about them because they made it to publishing probably by indicating a positive or promising result. Contrarily, there exist a hundred times unpublished, unreported works on produced water; works rejected based on not yielding desirable results or not being innovative enough. We might have encountered undesirable results but to what depths and time have we committed to mining out intricate details. The world is thinking and demanding sustainability. Is it sustainable for the future of water treatment, the ease and pace at which we transition to the next chemical or treatment option? In this data-centred approach, three common chemicals, aluminium sulphate, ferrous ammonium sulphate and calcium chloride, were used to treat produced water. The collected data (both initial and final analysis) were inferentially analysed. The first statistical analysis was the testing of 2 hypotheses using the Analysis of Variance test. This was done to reveal to compare the dependence of produced water properties on two categorical variables (sample type and treatment chemicals). The second was the test for relevance: correlation and regression analyses. The laboratory experimental analysis revealed that aluminium sulphate was most suitable for the alteration of physical effluent characteristics; ferrous ammonium sulphate for salinity concerns and calcium chloride for a particular heavy metal’s stability. The overall effluent characteristics indicated a greater dependency on ‘sample type’ than ‘treatment chemicals’. Certain produced water properties relationships were highlighted and quantified for instance iron(II) and chloride ion concentrations were dependent on total solids and indicated a significance F of 0.01.

The increasing global demand for hydrocarbon has brought new challenges in the petroleum reservoir's drilling process. Non-biodegradable chemical additives are used in drilling fluid and it leads to endangering the environment and personnel safety. Thus, there is a great need for new biodegradable drilling fluid additives that can protect the environment and personal safety while drilling is done well. This study with help of microbial analysis investigates the effects of in situ bacteria to degenerate the gasoline inside the oil-based mud, in the returned lubricant from one of the oil wells next to the Hawizeh Marshes. Four types of bacteria inside the oil-based mud were observed. According to the high growth and degradation of crude oil, one strain was selected. Determination of the coagulase and clumping test shows that the isolated strain belongs to staphylococcus. We investigate the performance of the staphylococcus bacterium on the lubricant from biological degradation aspects, using a gas chromatography technique. It was observed that the exposure of a small amount of the bacteria against 10 mL of lubricant indicates a considerable degree of degeneration, only in a few days. The residual crude oil in the culture medium was analyzed by gas chromatography (GC) and SARA. The results confirmed that the strain can degrade crude oil and produce lighter hydrocarbon. The saturate fraction increased about 23%, while the Resin and Asphaltene fractions decreased about 11% and 12%, respectively. This research is the first report on the characterization of crude oil-degrading bacteria from in situ bacteria at Hawizeh Marsh and by using this bacterium in the field the effect of oil pollution can be reduced on this marsh environment in a few days.

Wax precipitation has become a serious problem for the petroleum industry. The problem occurs when there is equilibrium disturbance on the pressure and temperature as well as crude oil composition. Wax deposits will eventually result in restriction of the fluid flow inside the pipeline, and severe deposition will cause blockage. The chemical additives currently being implemented in the industry have various limitations including the high cost and the irreversible impact it has on the environment. Therefore, the use of cheaper organic wax inhibitor obtained from crude palm oil (CPO) and crude palm kernel oil (CPKO) on the rheology and deposition of wax was investigated by using Chenor waxy crude oil from the Penyu basin, Pahang, Malaysia. To compare the efficiency of palm oil additives in inhibiting wax deposition, currently utilized chemical additives such as triethanolamine (TEA) and ethylene vinyl acetate (EVA) were also examined. The pour point of the crude oil was determined using SETA cloud & cryostat, while the rheological behavior of the crude was determined using a rotational Fann viscometer. The results obtained from this study reveal that CPO and CPKO could be used to improve the flow of crude oil, especially when 1 wt.% CPO or when 0.5 wt. % CPKO is used. It was also noted that the palm-based additives were much more effective at reducing the viscosity of the Chenor crude oil than the commercial wax inhibitor tested (TEA and EVA).

The Barail sandstone in the Surma Basin is a medium- to coarse-grained pinkish-colored rock exposed near the northeastern margin of Bangladesh. In this study, we evaluated the reservoir quality of the Barail sandstone based on its petrophysical and petrographic characteristics. Petrophysical analyses of outcropped samples showed that sandstones are made up of 16.48% porosity and 132.48 mD permeability. Sandstone density ranges from 1.94 g/cm3 to 2.37 g/cm3, with a mean value of 2.12 g/cm3, shown as moderately compacted sandstone. Integrated data such as bulk density, porosity, permeability, Rock Quality Index (RQI), Normalized Porosity Index (NPI), Flow Zone Indicator (FZI), compressive strength, etc. with their relationships indicate that Barail sandstone owing characters to become a good petroleum reservoir. The rock samples consisted mainly of quartz with an insignificant amount of rock fragments and plagioclase feldspar and are categorized as sub-arkose to sub-litharenite. The rock samples also contains lithic (andesine, microcline, muscovite, biotite, etc.) of granitic and gneissic fabric and some volcanic product like aguite, albite, andesine, garnet, spinel and ulvo-spinel indicating the source of nearby orogeny. The euhedral to subhedral shape of the quartz grain in a porphyritic texture, moderately sorted with a smaller amount of clay minerals indicating the moderately mature rock type. The iron oxide border around the quartz grain also indicates that the Barail sandstone was deposited under dry climatic condition.

Transportation of heavy crude oil through pipelines poses a great challenge in oil and gas industry. Crude oil chokes the pipelines when the temperature drops below the pour-point temperature. In the present study, a bio-based additive, i.e., Cashew Nut Shell Liquid (CNSL) has been tested as a flow improver for heavy crude. CNSL was obtained from waste cashew nut shell by means of mechanical extraction, and it was completely characterized. Similarly, the crude oil used in the study was characterized for its physio-chemical properties. Also, the crude oil was subjected to Saturates, Aromatics, Resins and Asphaltene analysis and Fourier Transform Infra-Red analysis. The raw and additive-treated crude oil with different CNSL dosages were subjected to pour-point and rheology measurements and optical micro-imaging analysis which indicated a remarkable improvement in flow whereby an optimum dose of 2000 ppm was observed. Furthermore, the effects of different parameters like shear rate, concentration of the flow improver and the effect of temperature on the crude oil flowability were studied. The process variables were optimized by means of Taguchi method, and the percentage contribution of each parameter was identified with the help of ANOVA table. The results indicate that a remarkable improvement in flow was observed at an optimum dose of 2000 ppm. The contribution of the concentration was found to be around 53%, whereas the contributions of the shear rate and the temperature were only 18.08 and 28.91%, respectively. Therefore, it has been observed that CNSL flow improvers extracted from cheap reasonable resources are more effective as they are cost-effective and eco-friendly when compared to conventional additives.

This study reports the extraction and performance evaluation of two bio-derived polymers for enhanced oil recovery applications. The oil displacement processes were conducted using six (6) unconsolidated sandstone core plugs. Reservoir permeability tester was used to simulate real reservoir conditions in order to evaluate the suitability of the formulated biopolymers for oil displacement applications at laboratory conditions. The experimental results indicate the effectiveness of the biopolymer solutions in enhanced oil recovery in terms of their superior incremental oil recoveries after conventional waterflood with percentage oil recovery of 30.9–39.3% for banana peel derived polymer and 40.6–50.8% for mango kernel derived polymer compared to conventional waterflood with percentage recovery of 16.2–32% of the initial oil in place. This work identified the potential suitability and use of bio-derived polymers for enhanced oil recovery applications with emphasis on their biodegradability.

This work investigates the efficacy of a biodegradable natural product, litchi leaves powder (LLP) as a filtration loss control agent in the water-based drilling fluid formulations. In order to evaluate the potential of litchi leaves powder (LLP), a strict protocol of experimentations according to API (American Petroleum Institute) standard has been followed. The experimental outcome showed that before hot rolling and after hot rolling of mud samples at 100 °C it was observed that 3–5% Concentration of LLP significantly increased the rheological parameters such as PV, YP and gelation of drilling fluid as compared to reference mud. Also, LLP reformed the filtration loss control characterization, suggesting a better biodegradable fluid loss reducing agent. After hot rolling at 100 °C for 18 h, the water-based drilling fluid with LLP as an additive showed a marked reduction in filtration control property as compared to reference Mud (RM). Experimental results concluded that 5% concentration of LLP significantly reduced the filtration loss of drilling fluid by 70.6% as compared to reference mud under the influence of 100 psi pressure. However, the conventional fluid loss additive CMC (LVG) reduced the filtration loss by maximum 67.5% as compared to reference mud. Therefore, LLP can be used as an alternative to CMC (LVG) in water-based drilling fluid with a maximum subsurface temperature of 100 °C.

In the future, oil shale will be an important energy resource. Froth flotation is a new method increasing the usability of oil shale. In this paper, oil shale samples were characterized based on their mineral composition, proximate analysis, ultimate analysis, size distribution, and density analysis. In addition, the flotation performance of oil shale was investigated. The effects of pulp concentration, agitation speed, aeration rate, and the type of reagents on the flotation performance were explored. Analysis of the samples’ characteristics indicates that cleansed oil shale is highly usable. The optimal flotation performance occurred for a pulp concentration of 50 g/L, a collector dosage of 1000 g/t, a frother dosage of 300 g/t, an agitation speed of 1900 rpm, and an aeration rate of 160 L/h. Froth flotation is a mature method and is widely used, and thus, it can be used to improve the industrial production of oil shale.

The limitation in the formulation and application of synthetic surfactants in petroleum industry is owing to their high cost of production or importation and their associated toxic effect which have been proven to be harmful to the environment. Hence it is vitally imperative to develop an optimum surfactant that is cost-effective, environmentally safe (biodegradable) and equally serves as surface acting agent. This study discusses the production of microbial produced bio-surfactant and its application in enhanced oil recovery. The bacteria Pseudomonas sp. were isolated from urine and allow to feed on neem seed oil as the major carbon source and energy. The crude bio-surfactant produced from the fermentation process was used to prepare three (3) solutions of bio-surfactants at different concentrations of 5 g/500 mL, 10 g/500 mL and 15 g/500 mL, and their suitability for enhanced oil recovery (EOR) was evaluated. Reservoir core samples and crude oil collected from the Niger Delta field were used to evaluate the EOR application of the microbial-derived surfactants. The sets of experimental samples were carried out using core flooding and permeability tester equipment, and the results obtained were compared with conventional waterflooding experiments. The three bio-surfactant concentrations were observed to recover more oil than the conventional waterflooding method for the two core samples used. Optimum performance of the produced microbial-derived surfactant on oil recovery based on the concentrations was observed to be 10 g/500 mL for the two samples used in this study. Therefore, eco-friendly bio-surfactant produced from neem seed oil using Pseudomonas sp. has shown to be a promising potential substance for enhanced oil recovery applications by incremental recoveries of 51.9%, 53.2%, and 29.5% at the concentration of 5, 10, and 15 g/500 mL and 24.7%, 28.7%, and 20.1% at concentration of 5, 10, and 15 g/500 mL for the two core samples, respectively.

Trinidad and Tobago (TT) is seeking to develop more economical methods of enhanced oil recovery to arrest the decline in crude oil production and to meet the current and future energy demand. The utilization of alkaline-polymer flooding to enhance oil recovery in TT requires key studies to be conducted to obtain critical information of the flooding system (soil type, additive type, pH, adsorption characteristics and rheological (flow) characteristics). Understanding the role of, interplay and optimizing of these variables will provide key input data for the required simulations to produce near realistic projections of the required EOR efficiencies. The parameters of various wells in TT were compared to the screening criteria for alkali-polymer flooding, and the EOR 4 well was found to be suitable and thus selected for evaluation. Laboratory adsorption studies showed that the 1000 ppm xanthan gum flooding solution containing 0.25% NaOH exhibited the lowest absorption capacity for the gravel packed sand and exhibited the lowest viscosity at all the tested shear rates. The lowest adsorption was 2.27 × 10−7 lbmole/ft3 which occurred with the 1000 ppm xanthan gum polymer containing 0.25% NaOH, and the evidence showed that the polymer was adsorbed on the other side of the faults, indicating that it has moved further and closer to the producing well. Implementation of an alkali polymer flooding resulted in an incremental increase in the recovery factors (~ 3%) compared to polymer flooding; however, a change in the oil recovery as a function of the alkaline concentration was not observed. The simulated economic analysis clearly shows that all the analysed EOR scenarios resulted in economically feasible outcomes of net present value (NPV), Internal Rate of Return (IRR) and payback period for oil price variations between $35 and $60 USD per barrel of oil. A comparison of the individual strategies shows that the alkali-polymer flood system utilizing 0.25% sodium hydroxide with 1000 ppm xanthan gum is the best option in terms of cumulative production, recovery factor, NPV, IRR and time to payback.

The hydrocarbon extraction and exploitation using state-of-the-art modern drilling technologies urge the use of biodegradable, environment-friendly drilling fluid and drilling fluid additives to protect the environment and humanity. As more environmental laws are enacted and new safety rules implemented to oust the usage of toxic chemicals as fluid additives, it becomes inevitable that we re-evaluate our choice of drilling fluid additives. Drilling fluids and its additives play a crucial role in drilling operations as well as project costing; hence, it is needed that we develop cost-effective environment-friendly drilling fluid additives that meet the requirements for smooth functioning in geologically complex scenarios as well as have a minimal ecological impact. The current research work demonstrates key outcomes of investigations carried out on the formulation of a sustainable drilling fluid system, where groundnut husk is used as a fluid loss additive and a rheological modifier having no toxicity and high biodegradability. Cellulose was generated from groundnut husk at two varying particle sizes using mesh analysis, which was then compared with the commercially available PAC at different concentrations to validate its properties as a comparable fluid loss retarder additive as well as a rheological modifier. In the present work, various controlling characteristics of proposed groundnut husk additive are discussed, where comparison at different concentrations with a commercially available additive, PAC, is also validated. The API filtration losses demonstrated by the (63–74) µm and the (250–297) µm proposed additive showed a decrease of 91.88% and 82.31%, respectively, from the base mud at 4% concentration. The proposed husk additives acted as a filtrate retarder additive without much deviation from base rheology and with considerably higher pH than the base mud. This investigation indicates that the proposed fluid loss additive and rheological modifier can minimize the environmental hazards and have proved to be a cost-effective eco-friendly alternative in this challenging phase of the hydrocarbon exploration industry.

Application of nanofluids flooding in the oil and gas industry is recently emerging as enhanced oil recovery methods. Nanoparticles have the ability to alter the rock formation in order to recover oil trapped in the pores of the rock to improve oil recovery. In this study, core plug samples were formulated in the laboratory to investigate the effect of nanoparticles on oil recovery. The formulated core samples were saturated in low salinity brine. However, low salinity brine was used because it has the ability to alter rock wettability. After core flooding with brine for secondary recovery process, extracted oil from Irvingia gabonensis was introduced into the formation to investigate the effect of Irvingia gabonensis on oil recovery. The result of the study showed that magnesium oxide, silicon oxide, aluminum oxide and zinc oxide had oil recovery of 38.1%, 45.6%, 47.7% and 35.1%, respectively. However, when the nanofluids with Irvingia gabonensis were injected into the formation as a displacing agent, the oil recovery greatly improved to 50.3%, 52.0%, 53.2% and 52.4% for (MgO, SiO2, Al2O3 and ZnO). The result of the study showed that nanofluid flooding is a promising potential to improve oil recovery in the Niger Delta.

In previous studies, it has been found that the Nigerian bentonite is deficient in terms of its fluid loss and rheological properties which includes yield point. Also, due to its high calcium content and low sodium content as opposed to foreign bentonite, it does not meet the API standard of drilling. This research was carried out to beneficiate the Nigerian bentonite as regards its fluid loss properties, rheological properties and wellbore stability. Snail shell is seen as waste substance in Nigeria, and Mucuna solannie on the other hand is a local major food supplement in Nigeria and is found in large quantities. The elemental and oxide compositions of the snail shell and Mucuna solannie were determined through scanning electron microscope and X-ray diffraction measurements, respectively. The additives were used to beneficiate the Nigerian bentonite, and the test result proved that at considerable concentrations of the additives, the Nigerian bentonite was able to compete with foreign bentonite and also met API specifications. Both additives contain high concentrations of nanoparticles and inhibitive calcium and potassium for wellbore stability. Beneficiated Nigerian bentonite also proved to be viable economically when compared with foreign bentonite.

The economy of Trinidad and Tobago which mainly relies on its energy sector is facing significant challenges due to declining crude oil production in a low commodity price environment. The need for enhanced oil recovery (EOR) methods to meet the current and future energy demands is urgent. Studies on the use of polymer flooding in Trinidad and Tobago are limited, especially in terms of necessary data concerning the characterization of the adsorption of polymer flooding chemicals such as xanthan gum and aquagel polymers on different soil types in Trinidad and the viscosity characteristics of the polymer flooding solutions which affect the key attributes of displacement and sweep efficiency that are needed to predict recovery efficiency and the potential use of these flooding agents in a particular well. Adsorption and viscosity experiments were conducted using xanthan gum and aquagel on three different soil types, namely sand, Valencia clay (high iron) and Longdenville clay (low iron). Xanthan gum exhibited the lowest adsorption capacity for Valencia clay but absorbed most on sand at concentrations above 1000 ppm and Longdenville clay below 1000 ppm. At concentrations below 250 ppm, all three soil-type absorbent materials exhibited similar adsorption capacities. Aquagel was more significantly absorbed on the three soil types compared to xanthan gum. The lowest adsorption capacity was observed for Valencia clay at concentration levels above 500 ppm; however, the clay had the highest adsorption capacity below this level. Sand had the highest adsorption capacity for aquagel at concentrations above 500 ppm while Longdenville clay was the lowest absorbent above 500 ppm. Generally, all three soil types had a similar adsorption capacity for xanthan gum at a concentration level of 250 ppm and for aquagel at a concentration level of 500 ppm. The results offered conclusive evidence demonstrating the importance that the pore structure characteristics of soil that may be present in oil wells on its adsorption characteristics and efficiency. Xanthan gum polymer concentration of 2000 ppm, 1000 ppm and 250 ppm showed viscosities of 125 cp, 63 cp and 42 cp, respectively. Aquagel polymer concentrations of 2000 ppm, 1000 ppm and 250 ppm showed viscosities of 63 cp, 42 cp and 21 cp, respectively. Aquagel polymer solutions were found to generally have lower viscosities than the xanthan gum polymer solutions at the same concentration. Adsorption and viscosity data for the xanthan gum and aquagel polymers were incorporated within CMG numerical simulation models to determine the technical feasibility of implementing a polymer flood in the selected EOR 44 located in the Oropouche field in the southwest peninsula of the island of Trinidad. Overall, aquagel polymer flood resulted in a higher oil recovery of 0.06 STB compared to the xanthan gum polymer flood, so the better EOR method would be aquagel polymer flood. Additionally, both cases of polymer flooding resulted in higher levels of oil recovery compared to CO2injection and waterflooding and therefore polymer flooding will have greater impact on the EOR 44 well oil recovery.

One of the major concerns during the production of crude oil especially in tropical waters is the deposition of wax on to the walls of the pipeline. This is due to the low seabed temperatures which can be below the wax appearance temperature (WAT) which leads to wax depositing out through molecular diffusion. Currently, there are many methods to prevent and remedy wax deposition but most of these solutions pose a serious environmental threat and are expensive to produce. Hence, this research investigated the use of an organic and cheaper alternative by utilizing synthetic fatty acid esters such as oleic acid which has shown promising results in reducing the pour point of waxy crude oils. The solution that was used was of palm oil origin, crude palm oil (CPO) and crude palm kernel oil (CPKO) and was subsequently compared with the pour point depressant and wax inhibition efficiency of the current industry used inhibitors utilizing the SETA Pour Point and Cloud Point as well as the cold finger apparatus. It was observed that the palm oil inhibitors were highly effective at 1 wt.% due to the high composition of oleic acid present portraying a similar result to Triethanolamine (TEA) while Ethylene Vinyl Acetate (EVA) performed best at low concentration of 0.1 wt.% but deteriorates significantly as the concentration increases due to the polar end agglomerating among itself.

Conventional treatment of drill cuttings, as drying and thermal desorption, is failing to meet environmental and economic standards; therefore, new alternatives for the treatment of this waste must be developed. The purpose of this study was to remove n-paraffin from drill cuttings using microemulsion systems (MES). The extraction percentage (%) of n-paraffin was quantified by gas chromatography with a flame ionization detector. The optimization of extraction parameters showed that the extraction percentage (%) is directly proportional to the stirring speed and contact time and inversely proportional to the HLB of the surfactant used in the microemulsion system. Results for MES using Alkonat® L90 and Renex® 95 were similar, but Alkonat® L90 was chosen as the best system considering the environmental issue. The MES/cuttings ratio did not influence the percentage of n-paraffin extracted, reaching 55.03% and 56.32% for the ratios of 0.5 and 2.0, respectively. The reuse of MES in multiple extractions showed that MES can be reused in up to two extractions, obtaining up to 86% extraction. The optimal parameters for Alkonat® L90 microemulsion systems were MES/cuttings ratio of 1.0, stirring speed of 132 strokes, and contact time of 80 min, achieving 86.27% extraction. Results obtained in this study may help to better understand n-paraffin removal from drill cuttings by MES, considering the future use of this technology in the design of an industrial treatment plant for both onshore and offshore operations.

In this work, experiment was carried out resulting in the utilization of local viscosifiers as substitute to conventional method (PAC-R) for hole cleaning purposes in drilling mud. The proposed viscosifiers are Irvingia gabonensis (Ogbono) and Abelmoschus esculentus (Okro) as alternative to the imported poly-anionic cellulose-regular (PAC-R) which is used in cutting carrying capacity efficiency. Laboratory tests were carried out on the proposed viscosifiers to evaluate their rheological properties. Slip velocity, annular velocity, shear stress, shear rate and cuttings transport efficiency on hole cleaning parameters were calculated to ascertain the effectiveness of the proposed viscosifiers in comparison with the conventional one (PAC-R). The results of the study showed that the proposed viscosifiers Sample B Irvingia gabonensis (Ogbono) had cutting carrying capacity of 96% for 5, 8, 10 and 15 (g), respectively. However, Sample C Abelmoschus esculentus (Okro) had 96% for 5 g and 8 g and 95% for 10 g and 15 g on the cutting transport efficiency. Based on the result of this work, the proposed viscosifiers compared favorably to that of PAC-R on hole cleaning and cutting carrying capacity.

The non-biodegradable additives used in controlling drilling fluid properties cause harm to the environment and personal safety. Thus, there is a need for alternative drilling fluid additives to reduce the amount of non-biodegradable waste disposed to the environment. This work investigates the potential of using mandarin peels powder (MPP), a food waste product, as a new environmentally friendly drilling fluid additive. A complete set of tests were conducted to recognize the impact of MPP on the drilling fluid properties. The results of MPP were compared to low viscosity polyanionic cellulose (PAC-LV), commonly used chemical additive for the drilling fluid. The results showed that MPP reduced the alkalinity by 20–32% and modified the rheological properties (plastic viscosity, yield point, and gel strength) of the drilling fluid. The fluid loss decreased by 44–68% at concentrations of MPP as less as 1–4%, and filter cake was enhanced as well when comparing to the reference mud. In addition, MPP had a negligible to minor impact on mud weight, and this effect was resulted due to foaming issues. Other properties such as salinity, calcium content, and resistivity were negligibly affected by MPP. This makes MPP an effective material to be used as pH reducer, a viscosity modifier, and an excellent fluid loss agent. This work also provides a practical guide for minimizing the cost of the drilling fluid through economic, environmental, and safety considerations, by comparing MPP with PAC-LV.

The objective of this study is to optimise the flotation process that separates crude oil and water from anionic polymer (GLP-100) via response surface methodology. Hence, a model was developed to describe the efficiency of oil removal under the influence of GLP-100 concentration, gas flowrate, and duration of flotation. Confirmatory experiments were performed to validate the model at a randomly selected point which was at 450 ppm of polymer concentration. At this point, the optimum values of the flotation parameters were recorded: 3 L/min of gas flowrate and 6 min of flotation time with 99% efficiency. The predicted values seemed to match the actual value with standard deviation 0.252%. The outcomes prove that this model can be used to optimise the flotation process in the presence of GLP-100 polymer.

The effectiveness of using waste bio materials as viscosity reducing agents was investigated on light and heavy crude oils of Oman. The selected materials are fiber of palm tree, date palm kernel and walnut shell. The utilization of waste bio materials is not only considered as a cost effective, but, environmentally friendly and has less effect on crude oil processing as compared to that of chemical additives. In this study, special piping structure was constructed to measure flowabilty time of crude oil. It was observed that use of bio materials reduced oil flowability time by range of 42–50% using particle size 75 µm and by 66% using particle size 150 µm. Moreover, the effect of different additives and various concentrations of bio materials on oil rheological properties, for instance viscosity and yield stress, were also studied. Results showed that the light crude oil exhibits a non-Newtonian viscoplastic behavior following (Bingham plastic model) whereas the heavy crude oil exhibits a non-Newtonian pseudoplastic behavior (shear thinning model). The use of bio materials reduced the limiting viscosities of the light crude oils by 62% using particle size 75 µm and 75% using particle size 150 µm. However, limiting viscosity of heavy crude oil was reduced by 15%. In addition, it was observed that using bio materials lowered yield shear; light crude reduced by average 32% while heavy crude oil reduced by 10%.

In less than a decade, there have been two global meltdowns of crude oil price and the latest was caused by the spread of coronavirus disease (COVID-19) in 2020. This is expected to have a negative impact on the global economy, especially on those countries that depend more on the revenue from sales of crude oil. One of the measures that can be taken to survive this kind of situation in the future is to reduce the unit technical cost for producing a barrel of oil by using locally available materials. This research investigated a local clay sourced from Ropp in Plateau State, Nigeria, by considering its rheological characteristics and economic implications of using it for partial to total substitution of imported bentonite clay for oil and gas drilling operations. The local clay was termed as Ropp bentonite clay (RBC). Various spud mud samples were prepared by dispersing a mixture of imported bentonite clay (IBC) and RBC (0–100%) in 350 ml of water. Certain quantity (0–1 g) of polyacrylamide cellulose was added to the mud samples before rheological and physical properties were determined using the standard API procedure. An economic model was built to determine the cost implications of using any of the mud formulations at different consumption rates. The results show that IBC–RBC blend in the right proportion could save Nigeria 12 to 36% of the cost of bentonite clay used to drill wells in the country.

The design and formulation of drilling fluids require additives that are cost-effective and environmental friendly in line with international best practices. This study was conducted to investigate the potentials and effects of Cyperus esculentus (Tiger Nut) as a filtrate loss modifier in field applicable aqueous and non-aqueous drilling fluids. Sixteen (eight aqueous and eight non-aqueous) drilling fluid systems were formulated, four aqueous and non-aqueous had Cyperus esculentus as a filtration additive, while the others do not contain the additive. The rheological properties, as well as the fluid filtration properties of the drilling muds, were investigated and compared with standard drilling mud. To ascertain validity, the results obtained were validated with the classic filtration model to ensure fit. Results obtained showed that the formulated mud systems had rheological properties that favored the suspension and transportation of drill cuttings, as well as the prevention of flocculation and clogging of drill strings. The rheological properties also showed a progressive trend as the concentrations of the additive were increased from 2 to 8 ppb. It was also further observed from the API and HPHT filter press test that the increase in the concentration of the additive exhibits a progressive trend that can be compared with the standard. In addition, it was observed from the classic filtration model that the experimental results from both mud systems were fit for the adopted model.

Matrix-acidizing operations have been accounted to be the most hazardous and environmentally harmful among all the well-stimulation techniques. For instance, diesel oil-based emulsified acids have been prohibited from usage due to their high level of toxicity. There is, therefore, a dire need for emulsified acids that are environmentally viable and technically competent to replace the diesel-based emulsified acids. In this study, a novel oil-based environmental friendly emulsified acid has been synthesized from Jatropha curcas oil and, then, compared against diesel and palm oil-based emulsified acids. The technical evaluation of the three acids has been done based on experimental results obtained from thermal stability, droplet size analysis, rheological study, acid solubility, and toxicity screening. In addition, core flooding experiments have been conducted to evaluate the performance of the three emulsified acids as well stimulants. The results revealed that Jatropha oil-based emulsified acid has the potential to replace diesel-based emulsified acid. Jatropha oil-based emulsified acid was found to perform better than the diesel-based emulsified acid as indicated by having greater thermal stability and more popular rheological properties at varying temperatures of ambient, 50 and 70 °C. Furthermore, it possessed a lower toxicity load and a higher retardation effect on acid solubility than that of the diesel oil-based emulsified acid. The core flooding results have also indicated better well-stimulation performance of Jatropha-based emulsified acid as compared with diesel-based emulsified acids.

A thermal desorption bench test device was assembled, and electromagnetic induction heating method was adopted. The obtained samples were tested at different terminal temperature and residence time, and the processing capacity of each test was about 15 kg. Total petroleum hydrocarbon (TPH) content dropped rapidly with the terminal temperature increasing from 200 to 400 °C, and the TPH removal rate reached 96% when terminal temperature rose to 400 °C. The terminal temperature should exceed the final boiling point of containing oil for effectively removal. The residence time increased from 20 to 30 min; drops of TPH content were obviously. Continued to increase the residence time after 30 min, the TPH content decrease became slowly. Results suggest that terminal temperature and residence time should be matched reasonably to achieve the best disposal effect. The residual oil content of solid slag reduced to 3 mg/kg under conditions of terminal temperature of 400 °C and residence time of 30 min. Low-speed stirring of the material in process was helpful to improve the disposal effect. In the process of removing oil, water contained was completely disposed. The sample quantity of bench test was much larger than that of laboratory experiment, and the results might be a direct guide for industrial applications.

An ecologically friendly water-based drilling mud (WBM) was designed by using wood wastes (WP: wood powder) in order to substitute the organic polymers which are very expensive and often make the higher cost of the oil well drilling. This present work is dedicated on studying the rheological behavior and main rheological properties of WBM containing the wood powder at different contents and sizes by substitution of usually used polymers. The effect of wood powder on the drilling fluid filtrate was also analyzed. The drilling fluid that was developed has better rheological properties and fluid loss control which are required for a good functioning of oil well drilling. By a total substitution of polymers, the wood powder (300 µm at 850 kg/m3) can be used as a filtrate reducer of mud because the WBM filtrate obtained exhibits a minimum and having requested values for such formation.

One of the most valuable wastes of the oil industry is oil sludge, found at oil wells, oil pipelines and refineries, and stored in storage units. Oil sludge has many similarities with heavy oil components. This study evaluates the use of oil sludge from the Iranian Oil Pipelines and Telecommunication Company for the manufacture of asphalt. The approximate structure of the oil sludge was analyzed and compared with the structure of conventional bitumen for road construction. Marshall asphalt samples were analyzed according to the American Society for Testing and Materials D1559 0–5–7.5–10–12.5 standard using 15% oil sludge with bitumen and aggregate. To study the physical characteristics of samples of Marshall asphalt, two important tests were performed (1) to determine the pressure resistance, and (2) the relative deformation of examples of all samples. The results showed that asphalt resistance is increased using 25–50% sulfur and 2–7% butadiene styrene polymer. Therefore, Marshall asphalt samples with 30% sulfur were prepared with bitumen and oil sludge. Fifty percent oil sludge in bitumen and a 2% polymer and 15% oil sludge mix with bitumen gave the best results. These mixtures are economically viable.

With the constant consumption of conventional oil and gas resources, unconventional oil and gas resources with great resource potential such as tight oil have gradually been valued and become the new exploration area. Jimsar Sag is the key tight oil exploration and development block in Junggar Basin of Northwestern China. Based on the data sets of geology, oil production test, logging, rock thin section, and geochemistry of Permian Lucaogou Formation (LCG), we studied the geochemical characteristics of hydrocarbon source rocks and their relation to the tight oil accumulation. Organic matter abundance of source rocks is high, the types of organic matter are mainly type I and type II, and the organic matter maturation is in the low mature stage to mature stage. Results of oil source correlation showed that the crude oil of sweet spots was mainly derived from the source rocks in the interior of the sweet spots. The LCG tight oil is mainly distributed in the plane where the source rocks have great thickness and the TOC is higher than 3.5%. It shows that the source rocks have obvious controlling on the occurrence and accumulation of tight oil.

Tight environmental regulations coupled with the constant need to enhance water-based drilling mud performance for use in deeper formation where it can withstand high temperature, high pressure and high saline condition have always been an existential issue during drilling operations. This research compared the performance of biodiesel produced from waste vegetable oil with that of white oil 5#, used as additives in mud formulations. Their effectiveness was tested at high temperature high pressure, in the presence of monovalent and divalent electrolytes. The mud density, rheological behavior, yield point, fluid loss under high temperature and pressure, and cake thickness were examined. The biodiesel emulsion mud proved more stable compared to both the white oil emulsion mud and the water-based mud without oil additive under thermal and saline conditions. The biodiesel emulsion mud demonstrated low and stable mud viscosity under the different conditions studied. The fluid loss reduction was better for biodiesel emulsion mud with API fluid loss of 2.20 cm3 and high temperature high pressure filtration loss of 9.4 cm3, while white oil emulsion mud gave 6.40 and 18.40 cm3, respectively, for both parameters at 180 °C in calcium-contaminated mud. The biodiesel emulsion mud exhibited superior qualities of rheological properties compared to white oil emulsion mud at higher temperature and saline conditions. The rheological models of the white oil emulsion mud and biodiesel emulsion mud at room temperature followed Bingham plastic model, but at high temperature their rheogram approximated to Herschel–Bulkley model.