Heavy Oil Production Research Articles

Prediction of Heavy Oil Production Based on Geomechanical Analysis in Entire Lifecycle of SAGD

ABSTRACTSteam‐assisted gravity drainage (SAGD) technology is an essential means of efficient development of heavy oil, super heavy oil, oil sands, and other unconventional resources in the world. Accurate prediction and evaluation of heavy oil output during SAGD production is a key step of construction optimization design and economic evaluation. The traditional prediction model of heavy oil production does not fully consider many geomechanical factors, such as rock deformation and permeability dynamic evolution. In this paper, a new mathematical model of crude oil production‐geomechanical coupling was established for three stages of the SAGD life cycle (steam chamber breakthrough stage, rising stage, and lateral dilation stage). The influence of the dynamic evolution of rock porosity and permeability on production was fully considered through the sensitivity coefficient of rock strain and permeability stress. It is found that the gap between the new model and the traditional model is larger when the strain and stress sensitivity of the reservoir body is larger. The value calculated by the conventional model is small when the reservoir dilates and large when the reservoir compresses. For Karamay heavy oil in Xinjiang, China, the steam breakout time predicted by the new model is 0.72, 1.50, 1.37, and 1.44 times the conventional model when the volumetric strain is 6%. The heavy oil production of Karamay, Xinjiang, China, Athabasca, and Cold Lake SAGD production areas in Canada was predicted. In the lateral dilation stage of the steam chamber, the predicted values of the model considering geomechanical factors were 1.44, 1.28, and 1.15 times the traditional model, respectively. This model can help field engineers obtain more accurate production of heavy oil and evaluate the significance of reservoir geomechanics in SAGD production.

Comparative analysis of wellbore electrical heating, low-frequency heating, and steam injection for in-situ conversion in continental shale oil reservoirs

In-situ conversion represents a potential method for developing immature continental shale oil, with efficient heating technology serving as its key component. This study employs coupled thermo-hydraulic-chemical numerical simulation techniques to comprehensively compare the feasibility and efficiency of three methods—wellbore electrical heating, low-frequency electrical heating, and steam injection—during the in-situ conversion process from the perspectives of reservoir heating efficiency, kerogen and heavy oil decomposition, and oil/gas production. The comparison reveals that steam injection, due to the introduction of significant water content, exhibits the poorest heating performance, whereas low-frequency electrical heating demonstrates the most effective results in reservoir heating. When employing electrical heating, particularly low-frequency methods, higher proportions of kerogen and heavy oil decomposition lead to increased overall oil and gas production. Steam heating offers advantages in heavy oil accumulation and production as well as wellbore protection, yet it yields higher water production as a drawback. Through an integrated discussion across five dimensions—heating capacity, wellbore protection, kerogen decomposition, heavy oil decomposition, and fluid production—we find that low-frequency electrical heating performs the best overall. The insights and comparisons discussed in this paper are expected to guide the selection and optimization of heating strategies for in-situ conversion.

Effects of Postweld Heat Treatment on Interfacial Behavior and Mechanical Properties of Joints Welded with Cu/Ni-Cr Alloy.

Welded cable composed of nickel-chromium (Ni-Cr) alloy and copper is a crucial component in the resistance heating technology used for heavy oil production. Tungsten inert gas (TIG) welding was employed to join the copper and Ni-Cr alloy using copper filler wire, and the stability of the welded joint was analyzed under high-temperature service conditions. We examined the changes in the microstructure and properties of the welded joint after postweld heat treatment (PWHT) at 600 °C for 3, 6, and 12 days. The results showed that the welded joint was appropriately formed, with fractures occurring in the copper substrate. The average tensile strength of the welded joint was 240 MPa. The copper and nickel dissolved into each other, forming a Cu0.81Ni0.19 strengthening phase. A columnar crystal diffusion layer formed at the interface between the Ni-Cr alloy and the fusion zone after welding. Grain boundary migration promoted the continuous growth in the columnar crystals as the PWHT duration increased, eliminating the microdefects and inhomogeneities caused by welding. The microhardness progressively decreased from the Ni-Cr alloy side to the copper side. However, the nanoindentation results at the Ni-Cr fusion line initially decreased and then increased with increasing PWHT duration, which contrasted the overall hardness trend observed across the joint after PWHT.

Producing aromatic‐rich oil through microwave‐assisted catalytic pyrolysis of low‐density polyethylene over Ni/Co/Cu‐doped Ga/ZSM‐5 catalysts

AbstractMicrowave (MW)‐assisted catalytic pyrolysis represents a promising method for transforming petroleum‐based plastic waste into valuable chemicals, offering a pathway towards more sustainable circular economy. In this study, catalytic pyrolysis of low‐density polyethylene (LDPE) was conducted under MW irradiation. The influence of various catalyst types (HZSM‐5, Ga/ZSM‐5, Ga/Ni/ZSM‐5, Ga/Co/ZSM‐5, and Ga/Cu/ZSM‐5) on product yield and distribution was examined. The results revealed that the Ga/ZSM‐5 catalyst yielded the maximum liquid oil, approximately 41%. Ga/Ni/ZSM‐5 performed excellently in the production of long‐chain olefins, constituting about 27% of the liquid fraction. However, Ga/Co/ZSM‐5 led to the production of heavy pyrolysis oil containing nearly 25% long‐chain paraffins, rendering it unsuitable for producing high‐value chemicals. Conversely, the Ga/Cu/ZSM‐5 catalyst yielded an aromatic‐rich pyrolysis oil, with benzene derivatives constituting approximately 90% of the liquid oil fraction, thus proving to be a suitable catalyst for the intended application. The liquid product distribution was compared with a petroleum assay by SimDist, and this suggested that utilizing the HZSM‐5 catalyst could yield an 86.4% naphtha fraction. The study also revealed that the Ga/Cu/ZSM‐5 catalyst generated the largest amounts of hydrogen and syngas, as determined by a MicroGC analysis of the gas products. This catalyst also exhibited the maximum coke deposition (1.35%) postreaction, which was attributed to its high aromatic hydrocarbon content in the pyrolysis oil and maximal hydrogen release. A comparison of fresh and spent catalyst properties was conducted to gain insights into catalyst activity and to correlate the effects of metal doping on product distribution. These findings underscore the potential of MW‐assisted catalytic pyrolysis, particularly with the Ga/Cu/ZSM‐5 catalyst, for the efficient conversion of plastic waste into valuable chemicals, thereby contributing to sustainable resource utilization and environmental conservation.

Multiphysics Field Coupled to a Numerical Simulation Study on Heavy Oil Reservoir Development via Electromagnetic Heating in a SAGD-like Process

Conventional thermal recovery methods for heavy oil suffer from significant issues such as high water consumption, excessive greenhouse gas emissions, and substantial heat losses. In contrast, electromagnetic heating, as a waterless method for heavy oil recovery, offers numerous advantages, including high thermal energy utilization, reduced carbon emissions, and volumetric heating of the reservoir, making it a focus of recent research in heavy oil thermal recovery technologies. This paper presents a numerical simulation study of electromagnetic heating for heavy oil recovery, using a heavy oil block in the Bohai Bay oilfield in China as a case study. Firstly, a multiphysics field coupled to a mathematical model was established, considering the impact of the temperature on the heavy oil viscosity, the threshold pressure gradient of non-Darcy flow, and the dielectric properties of the reservoir, along with heat dissipation from overlying and undercover sandstone and gravitational effects on fluid flow. Secondly, a numerical simulation method for the coupled multiphysics fields was developed, and the convergence and stability of the numerical simulation method were tested. Finally, a sensitivity analysis based on the numerical simulation results identified the factors affecting heavy oil production. It was found that electromagnetic heating significantly enhances heavy oil production, and the threshold pressure gradient greatly influences the prediction of heavy oil production. Moreover, heat dissipation from the overlying and undercover sandstone severely reduces cumulative oil production. When the production well is located below the electromagnetic heating antenna, larger well spacing results in higher cumulative heavy oil production. Higher heavy oil production is achieved when the antenna is positioned at the center of the reservoir for the studied cases. Power has a big effect on increasing heavy oil production, but its influence diminishes as power increases. There exists an optimal range of electromagnetic frequencies for maximum cumulative production, and higher water saturation leads to poorer electromagnetic heating efficiency. This study provides a theoretical foundation and technical support for the numerical simulation technology and development plan optimization of heavy oil reservoirs subjected to electromagnetic heating.

A dynamic solvent chamber propagation estimation framework using RNN for warm solvent injection in heterogeneous reservoirs

Warm solvent injection (WSI), injecting low-temperature solvent into formations to reduce the viscosity of heavy oil, is a clean technology for heavy oil production through reducing greenhouse gas emissions and water usage. The success of WSI operation depends on the uniform development and propagation of solvent chambers in reservoirs. However, reservoir heterogeneity stemming from shale barriers plays a detrimental role in the conformance of solvent chamber development and oil production rate. In this work, we developed a novel recurrent neural network (RNN)-based framework with the capability of efficiently tracking and estimating the solvent chamber positions in heterogeneous reservoirs based on only production time-series data. The developed estimation model utilizes the “sequence-to-sequence" mapping methodology to correlate observed production time-series sequence and solvent chamber edge sequence via a long short-term memory (LSTM) algorithm. The trained RNN models exhibit high accuracy, evidenced by the predicted dynamic solvent chamber locations match the corresponding true locations from numerical simulation, with a high coefficient of determination (R2) and a low mean squared error. Specifically, the achieved R2 values exceed 0.98 on both the training and testing data. The developed RNN-based workflow was tested via several cases from both regularly- and irregularly-shaped shale barriers, and the results were promising. The predicted solvent chambers showed strong agreement with those obtained from numerical simulations. The major benefits of this workflow include reducing computational time and saving overall monitoring and tracking costs for conventional techniques. The present work would provide a good demonstration of the capability of practical integration of machine learning methods in solving engineering problems.

Salt Tolerance of Fungi and Prospects for Mycodiagnostics of Contamination in Saline Soils

The review is devoted to the analysis of the characteristics of salt-tolerant fungi in order to identify the possibility of their use for indicating chemical contamination of highly mineralized soils and the search for potential test species for laboratory mycotesting. A list of representatives of halophilic and halotolerant genera of micromycetes is given, which can serve as indicators of pollution by heavy metals, oil products and other toxicants against the background of increased mineralization of soil substrates. For biotesting of soils with an average level of mineralization, micromycetes belonging to moderate halotolerant species are proposed as promising. The morphological, physiological and molecular mechanisms of adaptation of halophilic and halotolerant fungi to conditions of increased salinity of habitats are analyzed. The effects on fungal communities, which are caused by a combination of salinity with chemical pollution of different nature, are considered. Methodological aspects of the practical use of salt-tolerant fungi for biodiagnostics of the degree of unfavourability of saline soils are considered: the composition of media, cultivation conditions, and test reactions of fungal cultures that are optimal for an adequate assessment of the degree of halotolerance of fungi and ecotoxicity of soil samples.

Research on the Compounding Scheme of High-Efficiency and Environmentally Friendly Water-Based Well Cleaning Fluid and Analysis of Its Application Effect

In the process of oil well production, the deposition and enrichment of heavy oil and wax are common phenomena. The deposition of these high-viscosity organic substances will not only seriously affect the normal production of oil wells but also cause certain pollution to the environment. Traditional well-washing operations usually rely on high temperatures and strong cleaning chemicals, which have the problems of low cleaning efficiency at low temperatures and poor environmental protection. Therefore, it is particularly important to study a more efficient and environmentally friendly water-based well-washing fluid. At present, most oilfields in China use diesel or organic cleaning agents to clean oil wells, which not only increases the cost of well-washing operations but also may cause pollution to the environment. In response to this problem, the core of this study lies in its innovative compounding scheme. The scheme includes preferred alkaline components, surfactants, emulsifiers, and solubilizers, and introduces glass fiber cutting and erosion technology. This well-washing fluid can effectively remove wax and heavy oil attached to the well wall at a lower temperature, which not only improves cleaning ability but also greatly reduces the dependence on high temperature. The water-based well-washing fluid provided in this study is composed of water, alkaline substances, surfactants, emulsifiers, and glass fibers. Emulsifiers such as Tween 80, OP-20, and polyethers form a stable emulsification system to help disperse and encapsulate oil and grease particles.

In-situ upgrading of Egyptian heavy crude oil using matrix polymer carboxyl methyl cellulose/silicate graphene oxide nanocomposites

This study delves into catalytic aquathermolysis to enhance the economic viability of heavy oil production by in-situ upgrading technique. It is known that introducing nanocatalysts would promote the aquathermolysis reaction. Therefore, in this study, the effect of matrix polymer carboxyl methyl cellulose/silicate graphene oxide nanocomposites (CSG1 and CSG2) in the catalytic aquathermolysis of Egyptian heavy crude oil was studied. Characterization techniques including Fourier-transform infrared (FTIR), X-ray diffraction (XRD), Dynamic light scattering (DLS), Brunauer–Emmett–Teller (BET) surface area analysis, Scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were used to evaluate the structure of the synthesized nanocomposites. Results reveal CSG2 has higher crystallinity and superior dispersion compared to CSG1, and both exhibited a good stability in aqueous suspensions. CSG2 enriched with graphene oxide, demonstrates superior thermal stability, suitable for high-temperature applications such as catalytic aquathermolysis process. Single factor and orthogonal tests were used to assess the catalytic aquathermolysis performance of the prepared nanoparticles. The obtained results revealed that the optimum conditions to use CSG1 and CSG2 are 40% water concentration, 225 °C temperature, and 0.5 wt% catalyst percentage. Where, CSG2 showed better viscosity reduction (82%) compared to CSG1 (62%), highlighting its superior performance in reducing the viscosity of heavy oil. Numerical results from SARA analysis, gas chromatography, and rheological testing confirmed the catalytic aquathermolysis's efficacy in targeting asphaltene macromolecules and producing lighter hydrocarbon fractions.

MICROWAVE THERMOLYSIS OF HEAVY OIL IN THE PRESENCE OF AN IRON-BASED CATALYST

Global demand for energy is growing every year, and there is also a decrease in reserves of traditional hydrocarbons. Today, the share of highly viscous and bitumen oil reserves is 25 % of the world. Production of extra-viscous oils will grow around the world.In order to solve the problem of developing highly viscous and bitumen deposits and increase oil recovery, we offer a technology for using aquatermolysis catalyst. Experience in the use of in-situ chemical conversion of organic matter has shown sufficient effectiveness in solving this problem.In this work, laboratory studies were carried out to improve the rheological characteristics of highly viscous and bituminous oils using microwave exposure using an iron-based catalyst precursor.The addition of a catalyst precursor containing iron nanoparticles provides more uniform and higher-speed heating when the formation is exposed to high-frequency electromagnetic radiation. This heating technology has been used in various fields to achieve environmental safety and high energy savings, in comparison with traditional methods that cannot achieve these indicators. The proposed technology simplifies the development process by eliminating the injection of coolants, thereby providing prospects for the processes of intensification of production and its subsequent transportation.In order to assess the possibility of effective application of high-frequency electromagnetic radiation to the formation in a particular field, first of all, data on the rheological characteristics of oil after exposure should be presented.These laboratory studies showed a decrease in viscosity under microwave exposure in the presence of a catalyst up to 1.8 times compared to the original oil sample. A decrease in viscosity characteristics was recorded already from a five-minute microwave exposure, as well as a change in the component composition of the oil, the tar content decreases by 27 % relative to the initial oil sample. This combination of the two methods of action provides new opportunities for the development of new technologies, as well as more efficient production of heavy oil.

Classical and reactive simulations of plastic co-pyrolysis: Effects of polystyrene and its fragments on product yields, aggregation, and reaction mechanisms

Mixtures of polyethylene (PE), polypropylene (PP), polystyrene (PS), and their fragments such as ethylbenzene (EB) and linear alpha olefin (LAO) are simulated at different ratios using classical and reactive force fields. Using all-atom models validated by calculating conformations and diffusivities of differently sized PE melts in agreement with experiments, simulations are performed at 450 or 513 K that mimics a low temperature under the thermal co-pyrolysis condition, showing that the decomposition of PE into LAO influences densities and diffusivities of PE, to an extent dependent on PE lengths. In PE/PP/PS simulations, PS polymers aggregate at PS concentrations of 20 wt% or higher, leading to the separation between PS and other polymers. With the inclusion of EB that are assumed to be decomposed from PS, polymers do not aggregate. To understand reaction mechanisms, reactive simulations of PE and PS are performed, showing more heavy oil and less gas products at higher PS concentrations, in agreement with experiments, because PS fragments such as benzene, EB, and methylbenzene bind to PE and end up in heavy or light oils. In particular, the transfer of H radicals between PE and PS not only prevents further decomposition of polymers but also yields free radicals of polymers that can expedite co-pyrolysis. These findings help explain experimental observations regarding the effect of PS on liquid and gas product yields and suggest the optimal PS concentration without aggregation under the thermal co-pyrolysis condition, interpreted by reaction mechanisms of the transfer of H radicals and benzene fragments.

Riedel shear structures reactivation may induce earthquakes through long-term steam injection: A case study of a heavy oil production field in northwestern China

Conventional heavy oil exploitation methods involve steam stimulation and flooding. An oil field in northwestern China has been producing heavy oil via steam injection for several decades. The production area has been seismically quiet until an increase in seismicity occurred several years ago. An array of 40 seismographs has been deployed between July and October 2021 to monitor seismicity and resolve the possible causes of the recent seismicity. Using an end-to-end machine-learning-based high-precision earthquake location workflow, we analyze a microseismic sequence comprised of 178 events that occurred in the study area. Numerical simulations incorporating Coulomb failure stress suggest that prolonged steam injection can reactivate faults and induce seismic events. Similarly, fluid diffusion through conduits may achieve the same effect. Analysis of the focal mechanism solutions of 21 strike-slip and thrust events with [Formula: see text] in conjunction with the background stress regime ([Formula: see text] azimuth = N15°W) reveal that the stress distribution is compatible with a left-lateral Riedel shear structure (RSS) model. Therefore, we can speculate that steam injection may induce earthquakes by reactivating preexisting RSS fault structures. To conclude, the recent seismic events could have been induced by two possible mechanisms: (1) long-term steam injection may cause the static stress level on the faults beneath the reservoir to build up to critical levels, following which a slight stress disturbance can trigger an earthquake and (2) fluid conduits may transport condensed water to basement faults, weakening the faults through fluid diffusion.

Production Optimization of Heavy Oil Recovery Utilizing Mo-Ni Based Liquid Catalysts: A Simulation Approach

In recent years, the demand for heavy oil has increased due to its abundant availability and low cost. However, the extraction of heavy oil poses a significant challenge due to its high viscosity and low mobility. Therefore, various methods have been developed to enhance the recovery of heavy oil, including the use of catalysts. This study has created a unique simulation approach that uses liquid catalysts (LCs) to improve heavy oil recovery. In this work, laboratory testing dataset and numerical simulation studies were used to examine the potential of applying LCs as an alternative chemical agent for enhancing heavy oil recovery. CMG-STARS and CMOST modules were used to historical match the laboratory scale results of two sand-pack flooding experiments (water flooding and liquid catalyst flooding in tertiary recovery mode). Moreover, a sensitivity study was conducted to apply a wide range of assumptions to determine the most effective process controlling parameters. Finally, oil production optimization is performed using a genetic algorithm (particle swarm optimization) by selecting the optimum-operating parameters. In comparison to typical water flooding, the results revealed a discernible rise in the heavy oil recovery factor (RF) when injecting LCs. The simulation results showed that the optimized production strategy could increase the ultimate oil recovery by up to 45.06%. The injection rate, slug size, and injection temperature were found to be significant factors in optimizing the production of heavy oil. This simulation approach can be used to optimize the production of heavy oil using acidic Mo-Ni based liquid catalyst in different reservoirs.

Optimization of ESP performance through chemical treatment using a single capillary in the Apiay field

The future of production in the Apiay field lies in the T2 formation, although it poses significant challenges, such as high fluid encrustation and heavy crude oil production. These issues have led to strong emulsion problems and operational issues with many wells' electro-submersible pumping systems (ESPs). In response, companies have decided that all wells with ESP equipment in the T2 formation should undergo downhole treatment using capillary scale inhibitors and fluidity improvers. However, due to operational and design constraints, some wells only have one capillary, making it difficult to prioritize and decide on a single treatment. Ecopetrol and ChampionX have collaborated to develop a new flow improver that can be applied with the scale inhibitor in the same capillary without causing incompatibility or affecting product performance. This innovative solution was implemented in five wells, using 600 ppm for the flow improver, and 25 ppm for the scale inhibitor, resulting in a significant increase in crude oil production by up to 79%, USD 55.000 in cost savings in capillary system installation, 29% energy savings, and reduced emissions. This successful application is innovative and unique in Colombia, and it sets an example for other fields facing similar challenges in the couuntry, offering a promising approach to leverage heavy crude oil production and transform the future of these fields.

Factors, Mechanisms, and Kinetics of Spontaneous Emulsification for Heavy Oil-in-Water Emulsions.

In challenging reservoirs where thermal recovery falls short, cold or chemical oil recovery methods are crucial. Spontaneous emulsification (SE), triggered by gentle disturbance, significantly enhances oil recovery. In elucidating SE mechanisms and kinetics, SE processes via direct contact between oil and aqueous phases without stirring were conducted. The effects of temperature, emulsifier concentration, pH, NaCl concentration, and the oil-to-water ratio on SE were investigated through droplet size analysis and turbidity measurements. Furthermore, the emulsification mechanism and derived emulsification kinetics based on turbidity data were obtained. The results underscore the feasibility of SE for oil-water systems, reducing viscous and capillary resistances without agitation. The emulsified oil mass increased with the temperature, pH, and aqueous-to-oil phase volume ratio while decreasing with the NaCl concentration. In this study, for GD-2 crude oil, the optimal emulsified oil amount occurred at a betaine surfactant (BetS-2) emulsifier concentration of 0.45%. Microscopic photo analysis indicated narrow particle size distributions and small droplets, which remained stable over time under various experimental conditions. A combined SE mechanism involving ultralow interfacial tension, interfacial turbulence due to Marangoni effects, and "diffusion and stranding" due to in situ emulsifier hydrophilicity, was speculated. Additionally, an analogous second-order kinetic equation for SE was proposed, indicating exceptional correlation with calculated and experimentally measured values. This study offers theoretical insight for enhancing oil recovery in chemical and cold production of heavy oil in oilfields.

Molecular insight into the enhanced oil recovery potential of a seawater-based zwitterionic/anionic surfactant compound for heavy oil reservoirs

Zwitterionic/anionic surfactant mixtures can produce many synergistic effects that benefit heavy oil production. In this work, a seawater-based zwitterionic/anionic surfactant compound was prepared using cocoamidopropyl betaine (CAB) and alkyl polyoxyethylene ether sodium sulfate (AES), emphasizing their synergistic effects in enhancing conventional heavy oil recovery. First, the emulsification capability and the oil displacement efficiency of the surfactant compound were tested through laboratory experiments. Then the impacts of salinity, cation types, surfactant formulation and solution pH on surfactant-surfactant or surfactant-heavy oil interactions were systematically explored through molecular dynamics simulations to unveil the underlying mechanisms of enhanced oil recovery. The results showed that, (1) in a seawater-based system, when the AES/CAB concentration ratio was 1:1, a large wormlike micelle was formed due to the cation bridging of Ca2+ and Mg2+ ions, which not only strengthened the attractive interactions between the AES-SO4− and the CAB-N+ functional groups, but also screened the repulsive interactions between the AES-SO4− and the CAB-COO− functional groups. (2) Through mixed adsorption, the arrangement of AES/CAB molecules at the aqueous/heavy oil interface was more compact. (3) By incorporating the AES/CAB mixture into the associative structures of asphaltene and resins, it could effectively weaken the attraction interactions between the asphaltenes and the resins. Through these synergies, an additional oil recovery of 24.93 % was yielded by combining AES/CAB flooding and subsequent seawater flooding, compared to 19.38 % in the pure AES case. This study provides important insights into the microscopic mechanisms of zwitterionic/anionic surfactant mixtures, which can facilitate the effective development of heavy oil reservoirs and guide the complex formulation of cost-effective surfactant compounds.

Quantification of Methane Emissions from Cold Heavy Oil Production with Sand Extraction in Alberta and Saskatchewan, Canada.

Cold heavy oil production with sand (CHOPS) is an extraction process for heavy oil in Canada, with the potential to lead to higher CH4 venting than conventional oil sites, that have not been adequately characterized. In order to quantify CH4 emissions from CHOPS activities, a focused aerial measurement campaign was conducted in the Canadian provinces of Alberta and Saskatchewan in June 2018. Total CH4 emissions from each of 10 clusters of CHOPS wells (containing 22-167 well sites per cluster) were derived using a mass balance computation algorithm that uses in situ wind data measurement on board aircraft. Results show that there is no statistically significant difference in CH4 emissions from CHOPS wells between the two provinces. Cluster-aggregated emission factors (EF) were determined using correspondingly aggregated production volumes. The average CH4 EF was 70.4 ± 36.9 kg/m3 produced oil for the Alberta wells and 55.1 ± 13.7 kg/m3 produced oil for the Saskatchewan wells. Using these EF and heavy oil production volumes reported to provincial regulators, the annual CH4 emissions from CHOPS were estimated to be 121% larger than CHOPS emissions extracted from Canada's National Inventory Report (NIR) for Saskatchewan. The EF were found to be positively correlated with the percentage of nonpiped production volumes in each cluster, indicating higher emissions for nonpiped wells while suggesting an avenue for methane emission reductions. A comparison with recent measurements indicates relatively limited effectiveness of regulations for Saskatchewan compared to those in Alberta. The results of this study indicate the substantial contribution of CHOPS operations to the underreporting observed in the NIR and provide measurement-based EF that can be used to develop improved emissions inventories for this sector and mitigate CH4 emissions from CHOPS operations.

The Role of Amphiphilic Nanosilica Fluid in Reducing Viscosity in Heavy Oil

Heavy oil accounts for a considerable proportion of the world’s petroleum resources, and its exploitation helps to mitigate reliance on conventional oil resources and diversify energy supply. However, due to the high viscosity and high adhesion characteristics of heavy oil, conventional methods such as thermal recovery, emulsification, and dilution have significant limitations and cannot meet the growing demands for heavy oil production. In this study, 3-propyltrimethoxysilane (MPS) was used to modify and graft amphiphilic surfactants (AS) onto nanosilica to prepare a salt-resistant (total mineralization > 8000 mg/L, Ca2+ + Mg2+ > 1000 mg/L) and temperature-resistant (250 °C) nanosilicon viscosity reducer (NSD). This article compares amphiphilic surfactants (AS) as conventional viscosity-reducing agents with NSD. FTIR and TEM measurements indicated successful bonding of 3-propyltrimethoxysilane to the surface of silica. Experimental results show that at a concentration of 0.2 wt% and a mineralization of 8829 mg/L, the viscosity reduction rates of thick oil (LD-1) before and after aging were 85.29% and 81.36%, respectively, from an initial viscosity of 38,700 mPa·s. Contact angle experiments demonstrated that 0.2 wt% concentration of NSD could change the surface of reservoir rock from oil-wet to water-wet. Interfacial tension experiments showed that the interfacial tension between 0.2 wt% NSD and heavy oil was 0.076 mN/m. Additionally, when the liquid-to-solid ratio was 10:1, the dynamic and static adsorption amounts of 0.2 wt% NSD were 1.328 mg/g-sand and 0.745 mg/g-sand, respectively. Furthermore, one-dimensional displacement experiments verified the oil recovery performance of NSD at different concentrations (0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%) at 250 °C and compared the oil recovery efficiency of 0.2 wt% NSD with different types of demulsifiers. Experimental results indicate that the recovery rate increased with the increase in NSD concentration, and 0.2 wt% NSD could improve the recovery rate of heavy oil by 22.8% at 250 °C. The study of nano-demulsification oil recovery systems can effectively improve the development efficiency of heavy oil.

Phytoremediation of soils contaminated as a result of military and anthropogenic impact

Military conflicts and anthropogenic accidents cause significant soil contamination with heavy metals, oil products, pesticides, and other toxic substances. The purpose of this study was to highlight the factors of influence of military-anthropogenic load on soils and to analyse the available methods of their remediation. The study summarised the available and promising phytoremediation methods with an assessment of their impact on soil contamination by chemicals that are typical pollutants during military conflicts. The study summarised, classified, and compared the groups of pollutants that are most common during military operations; analysed the impact of pollutants on the fertile soil layer and their mobility; and analysed the available remediation methods. It was found that the available soil remediation technologies, which can be used individually or in combination, provide the necessary tools to address the problem of chemical contamination of soils due to toxic products such as explosive derivatives and heavy metals. The degree of economic feasibility was considered, which, accordingly, suggested that soil phytoremediation may be the most economically feasible under certain conditions. This opens wide possibilities for further investigations, where the synergy of ecology, economics, and agrobiology will enable the development of mechanisms for optimising soil phytoremediation methods, considering their type, profile, and intended use. An algorithm of actions for remediation of soils as a result of military-anthropogenic load was proposed, which includes a related set of related actions on zoning, demining, assessment, and return of land to industrial use. The findings of this study can be used to clean industrial areas that have been contaminated during production processes or accidents

Technical transformation of heavy/ultra-heavy oil production in China driven by low carbon goals: A review

With the growing global energy demand and limited production of conventional crude oil, the extraction of unconventional heavy and extra-heavy oil is receiving unprecedented attention. China is the fourth largest producer of heavy oil. High viscosity and complex formation environments increase the difficulty of exploiting heavy oil. To alleviate the economic cost and environmental pollution pressure brought by heavy oil production, China has achieved significant advancement in the innovation of heavy oil recovery, including accelerating the transformation of thermal technology to non-thermal technology and the use of new energy technology to achieve the goal of low-carbon economy and green environmental protection. Based on the background of heavy oil in China, this paper recharacterizes the high-viscosity mechanism of heavy oil. From different aspects, including basic principles, main characteristics, applicability, limitations, and challenges, this paper comprehensively reviews existing heavy oil recovery technologies, including thermal recovery, in-situ upgrading, cold recovery, and new energy technologies.Currently, in China, the main target of heavy oil recovery is achieving the “carbon peaking and carbon neutrality” goals, which can be described as low energy consumption, low emission, and low pollution. To facilitate the low-carbon transition in the extraction of heavy/extra-heavy oil and attain environmental sustainability goals, it is essential to increase the proportion of non-thermal factors in thermal recovery technologies, develop efficient in-situ catalysts, adopt clean cold extraction techniques, and advance the development of new energy technologies.