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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. [ABSTRACT FROM AUTHOR]

Heavy oil resources are abundant globally, holding immense development potential. However, conventional thermal recovery methods such as steam injection are plagued by high heat loss, substantial carbon emissions, and significant water consumption, making them incompatible with carbon reduction goals and the sustainable socioeconomic development demands. A new method of high-frequency electromagnetic in situ heating, which targets polar molecules, can convert electromagnetic energy into heat so as to achieve rapid volumetric heating of the reservoir. This method has the potential to overcome the drawbacks of traditional techniques. Nevertheless, it faces significant drawbacks such as limited heating range and inadequate energy supply during later production stages, which necessitates auxiliary enhancement measures. Various enhancement measures have been reported, including nitrogen injection, hydrocarbon solvent injection, or the use of nano-metal oxide injections. These methods are hindered by issues such as pure nitrogen being easy to breakthrough, high costs, and metal pollution. Through extensive literature review, this article charts the evolution of high-frequency electromagnetic in situ heating technology for heavy oil and the current understanding of the coupled heat and mass transfer mechanisms underlying this technology. Moreover, based on a profound analysis of the technology's progression trends, this work introduces a new direction: CO2-N2 co-injection as an enhancement strategy for high-frequency electromagnetic in situ heavy oil recovery. There is promising potential for the development of new technologies in the future that combine high efficiency, low carbon emissions, environmental friendliness, economic viability, and energy conservation. Furthermore, some research prospects in low-carbon situations and challenges for the new technology in future are presented in detail. All in all, the contribution of the paper lies in the summarizing of some main drawbacks of current enhanced electromagnetic in situ thermal recovery methods, and presents a novel research direction of using CO2-N2 co-injection as an enhancement strategy based on its current research status in low-carbon situations. [ABSTRACT FROM AUTHOR]

During the process of water injection, due to solid particle deposition and foreign liquid intrusion, the formation near the wellbore was contaminated and blocked. As a result, water injection rate reduced and failed to meet the injection requirements. In order to improve water injection rate and improve oil recovery of offshore oilfields, hydraulic injection tests were carried out in controlled laboratory conditions. In general, the formation of complex fracture patterns is an ideal outcome of the hydraulic fracturing stimulation seeks to achieve. In situ stress condition is an inherited geological condition one can only adopt to. By comparing test results of different experiments that had varied stress and hydraulic injection conditions imposed, we can investigate their impact on the fracture patterns created. This paper presents laboratory evidences to support that if the hydraulic injection condition is managed properly, a complex fracture pattern is possible even under a high in situ stress anisotropy. Even if the in situ stress condition has a large anisotropy, proper hydraulic stimulation operations can still cause complex fracture patterns and thus provide good stimulation efficiency. [ABSTRACT FROM AUTHOR]

The gas lift in the offshore M field will be performed with high CO2‐content associated gas, but the change of wellbore temperature and pressure during the injection process will lead to the change of phase and physical parameters of associated gas, which has a great impact on the design of gas lift. To ensure the smooth implementation of gas lift in the offshore M field, this paper conducts a study on the physical parameters of associated gas considering the change of CO2 phase state. We obtained the density, viscosity, compression factor, constant pressure specific heat capacity, thermal conductivity, and Joule Thomson coefficient at each temperature and pressure by Hysys calculation, and regression analysis to obtain the regression model of the physical parameters; finally, the regression model was compared with the flash experiment and Hysys calculation results. The results show that the CO2 phase change has a large influence on the physical parameters; R2 > 0.8, which indicates that the regression model has sufficient reliability; the results of the comparison show that the empirical formulas of all physical properties have sufficient accuracy and superiority except Joule–Thomson coefficients. In addition, the empirical formula of the Joule–Thomson coefficient also has good accuracy and superiority at the pressure not exceeding 22 MPa. The study of phase changes and physical parameters of associated gas with high CO2 content provides a basis for subsequent gas lift design in the offshore M field and multiphase flow calculations in the wellbore during the gas lift. Although this study is only applicable to this sample, it also provides a feasible research method for other samples. [ABSTRACT FROM AUTHOR]

Abstract In order to reduce energy consumption of water injection development of offshore platform, one idea of jet pumps with characteristics of suction replace the gate valve of water injection wells was introduced. Taking 14 injection wells at a platform in Bohai as the study object, three types of jet pumps which are called JP1, JP2 and JP3 were designed. The corresponding three-dimensional models were established and the Realizable k-ε model of ANSYS was applied to study the influence of jet pump nozzle-throat clearance on water injection rate. Moreover, the injection performance of structure-optimized jet pumps was tested. Three conclusions could be drawn. First, JP1, JP2 and JP3 express the best water injection performance with the optimal nozzle-to-throat clearance which is 4 mm, 5 mm and 6 mm. Second, the water injection rate could satisfy the demand of water injection platform and simulation results are similar to the experimental ones when the water injection rate range of three kinds of jet pump is 183–272 m3/d, 263–393 m3/d and 634–1149 m3/d respectively. Third, compared with the throttle valve water injection system at offshore platform, the jet pump water injection system could save about 1,150,000 kW h per year. Highlights • Three jet pumps are designed to replace the throttle for different flowrate and pressure conditions of injection wells. • The structure of jet pumps are optimized by numerical simulation and experiment. • Through the preliminary evaluation, about $182,000 can be saved per year after using jet pumps. [ABSTRACT FROM AUTHOR]

Abstract: Graphene oxide (GO) has been widely used to develop fluorescence resonance energy transfer (FRET) biosensors for tumor markers (e.g., matrix metalloproteinases, MMPs) due to its superior fluorescence quenching capacity and unique adsorption characteristics for biomolecules. In this study, fluorescein isothiocyanate-labeled peptide (Pep-FITC) was assembled onto the GO surface through covalent binding to construct a GO-Pep-FITC FRET sensor for sensitive, rapid, and accurate detection of MMP-2 in complex serum samples. Compared to similar GO-based FRET sensors fabricated through physical adsorption, the as prepared ones via covalent binding are significantly more stable under physiological conditions, enabling their detection of MMP-2 with high sensitivity (detection limit: 2.5ng/mL). More importantly, it allows for rapid MMP-2 detection (within 3h) even in complex biological samples with satisfactory accuracy and the relative standard deviation ≤7.03%. Our studies further suggest that such a platform developed here for sensitive, rapid, and accurate detection of biomarkers holds great promise for clinical diagnosis of protease-related diseases. [Copyright &y& Elsevier]