期刊,Journal of Petroleum Science & Engineering 2022年209卷期_国家学术搜索

期刊信息/Journal information

Journal of Petroleum Science & Engineering

Elsevier Science B.V.

主办单位：Elsevier Science B.V.

国际刊号：0920-4105

Journal of Petroleum Science & Engineering/Journal Journal of Petroleum Science & Engineering

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Experimental investigation of synergistic effect of non-ionic surfactant and smart water injection methods for enhanced oil recovery from carbonate reservoirs

Hooman MohammadshahiHamidreza ShahverdiMohsen Mohammadi

9页

查看更多>>摘要：In the water-based EOR methods, surfactants and smart water injection methods usually are employed to reduce the water-oil interfacial tension and altered the rock wettability, respectively. The main objective of this study is to employ the combination effects of non-ionic Surfactants (including KEPS 80 and Behamid D) and Smart water Flooding to alter the wettability and interfacial tension (IFT) towards the most favorable conditions. Contact angle, spontaneous imbibition, capillary pressure (Pc), and relative permeability (kr) experiments were performed at various concentrations of the surfactants and ions using carbonate rock to identify the various mechanisms occurring in the Surfactant and Smart water (SSW) flooding process and also to determine the additional oil recovery. The optimum concentrations of surfactant and positive ions (Mg~(2+), Ca~(2+)) were also obtained. In this regard, concentrations of the employed ions were optimized for altering the carbonate rock surface wettability toward the water-wet. The optimum surfactant concentrations obtained by Mohammadshahi et al. (2019) were also used, in this study. After obtaining the optimum concentrations, some promising aqueous solutions were designed for Amott cell, relative permeability, and capillary pressure experiments using the combination of surfactant and ions. Amott cell tests were implemented for comparing the ability of different aqueous solutions such as base water (Brine with 30,000 ppm NaCl), surfactant solution, smart water, and SSW solution in the oil recovery from the cores. Subsequently, relative permeability and capillary pressure experiments were performed. The results of contact angle experiments depicted that brine containing 24,000 ppm NaCl +6000 ppm Mg~(2+) yielded the lowest contact angle among the studied samples. In the spontaneous imbibition tests, the oil recovery was obtained to be 7.6% for the base water, 9.5% for the smart water (24,000 ppm NaCl + 6000 ppm Mg), 15.09% for the surfactant solution (1500 ppm KEPE in 30,000 NaCl), and 20.8% for the SSF water. The relative permeability and capillary pressure tests have demonstrated the change of residual oil saturation and wettability of rock while using the SSW method compared to other techniques (i.e. base water, surfactant injection, smart water flooding). Finally, the results indicated that the combination of smart water and surfactant injection could lead to a much higher recovery factor than each method alone.

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Better opportunities created for investors by evolution of petroleum contracts in Iraq under the background of the recovery of oil prices

Dufen SunLiangyu XiaKerning Wang

10页

查看更多>>摘要：In order to revitalize its economy and oil industry, Iraq has gradually opened up its oil and gas market to the outside world in the past decade through public bidding. Service contracts were mainly adopted in 2008. Though some contractors really made a profit, some blocks were not so attractive. For the purpose of improving the distribution of profits and risks between the federal government of Iraq and overseas contractors, the government has been constantly adjusting the fiscal terms of service contracts, and even introduced a new contract model-development and production contract in 2018. To provide an insight into the changes and its consequence, the process and the trend of change in the contracts over the past decade are summarized, and furthermore, a quantitative analysis is conducted with a financial model. Especially, given the importance of oil prices, a sensitivity analysis is introduced to examine how oil prices impact the income of overseas contractors under different contract models. The results indicate that the federal government was being in the process of gradually sharing equally with contractors the profits and risks arising from price fluctuation, and the new contract model, especially with the recovery of oil prices, is creating better opportunities for overseas oil companies.

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Modeling the spontaneous imbibition of non-Newtonian fluids into the fractal porous media of tight reservoirs

Yunxuan ZhuZhiping LiJun Ni

12页

查看更多>>摘要：This study proposes a new fractal model to describe the spontaneous-imbibition process of non-Newtonian fluids in tight reservoirs. In the new fractal model, the imbibed mass can be mainly expressed as a function of pore-geometry parameters, the rheological properties of non-Newtonian fluid, and contact angle. We validated the new model against experiments, which were conducted on three core samples collected from a tight reservoir in the Ordos Basin. Comparative analysis shows a relatively good match in imbibition profiles obtained by modeling and experiments at the early stage of imbibition. Unlike the Newtonian fluids, the modeling results suggest a non-linear relationship between imbibition distance and the square root of time when the tortuosity and non-Newtonian fluids are considered. This study may thus provide new insights into modeling the fracturing-fluid flow in tight reservoirs.

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NSTL

Spontaneous imbibition model for micro-nano-scale pores in shale gas reservoirs considering gas-water interaction

Ke WangBeibei JiangKairui Ye

20页

查看更多>>摘要：Spontaneous imbibition is the main factor that reduces the fracturing efficiency and damages gas production in shale gas wells, which is regulated by the gas-water interaction. Water (fracturing fluid) is imbibed spontaneously due to the characteristics of the water-rock interface, especially in shale with micro-nano-scale pores, while imbibition is not impeded but prevented by the pore structure resistance and original free gas compression as well as the increased fraction from the desorption of adsorbed gas. To accurately predict the fluid loss in a shale gas reservoir during fracturing, the imbibition pressures of the gas-water phase were comprehensively analyzed in this study, and the increased gas pressure from the desorption of adsorbed gas was first considered with other imbibition pressures, such as gas pressure from free gas compression, displacement pressure, capillary pressure, and osmotic pressure. By substituting the gas-water phase pressures into the Lucas-Washburn equation with the fractal characteristic of the capillary bundle, an imbibition model for micro-nano-scale pores in shale gas reservoirs considering gas-water interaction is established. The proposed model is compared with the traditional imbibition models and verified through imbibition experiments, and a case application to a shale gas well in the Sichuan Basin is undertaken. The results prove that the new fractal imbibition model performs better than the other models for imbibition estimation in reservoir shale, and it can accurately predict the fluid loss during the hydraulic fracturing process for shale gas wells.

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Study of thermally-induced enhancement in nanopores, microcracks, porosity and permeability of rocks from different ultra-low permeability reservoirs

Zijian WeiJ.J. Sheng

19页

查看更多>>摘要：Improving permeability is the crucial mechanism for further enhancing oil and gas recovery of ultra-low permeability reservoirs. To investigate the temperature sensitivity and stress sensitivity of permeability under an actual reservoir condition, heating treatment and real-time measurement of pulse-decay gas permeability (PDP) of cores collected from three different ultra-low permeability reservoirs were conducted in our self-developed high-temperature pseudo-triaxial core holder. To clarify the intrinsic relationship between the microstructure development and porosity-permeability enhancement, stereo light microscope (SLM) observation, computerized tomography (CT) scan and nuclear magnetic resonance (NMR) test were used to quantitatively characterize the dynamic variations in thermal cracks, nanopores and porosity. Based on the lithology analysis and thermal analysis, the primary mechanisms of nanopore evolution and thermal cracking for different ultra-low permeability rocks were analyzed in detail. The experimental results show that the permeability of Chang 8 ultra-low permeability sandstone and Longmaxi shale cores only increased by about one order of magnitude above the threshold temperature of 500 °C, while the permeability of Jimsar shale cores increased significantly by two orders of magnitude above the threshold temperature of 300 °C. Above their threshold temperatures, the permeability showed stronger stress sensitivity. The SLM observation and CT scan revealed that thermal cracks propagated rapidly above the threshold temperatures, which resulted in a substantial increase in temperature sensitivity and stress sensitivity of permeability. NMR test shows that the porosity of ultra-low permeability cores performed an increasing trend as the temperature rose. However, the nanopore structure in Chang 8 ultra-low permeability sandstone monotonously developed toward larger micron-sized pores, while the Longmaxi shale and Jimsar shale eventually re-evolved into smaller nanopores. We found that kerogen pyrolysis was the most critical mechanism leading to the microstructure, porosity and permeability enhancement in organic-rich shale. For organic-poor ultra-low permeability sandstone and shale, the quartz phase transition from a to p was considered as the key reaction for the thermal cracking and permeability improvement. By comparison, heating treatment has a higher thermal stimulation potential in shale cores from medium-to-low maturity shale oil reservoirs.

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The study of ultralow interfacial tension SiO2-surfactant foam for enhanced oil recovery

Pattamas RattanaudomBor-Jier Ben ShiauJeffrey Harry Harwell

12页

查看更多>>摘要：Surfactant selection and formulation are key factors in technological and economic success in chemically enhanced oil recovery (cEOR) applications. In this study, the silica nanoparticle (SNP) was added in an ultralow interfacial tension foam (ULIFT), called SNP-ULIFT foam, which was successfully prepared by ternary surfactant systems. The Carboxylate-based extended surfactant (Carboxylate), Dioctyl Sulfosuccinate Sodium salt (AOT), and Sodium Diphenyl Oxide Disulfonate (DODS) at a 0.48:0.48:0.04 wt ratio were conducted as the surfactant system. Remarkable results in the selected surfactant system were observed in terms of the ability to form foaming and ultralow interfacial tension (IFT) at 60 ± 2 °C with the ADNOC crude oil (Abu Dhabi National Oil Company) as model oil. The optimum salinity of the surfactant system was found at 2.5 wt% (8:2 Na:Ca by weight), indicating a minimum IFT of 0.0019 mN/m. The adsorption capacities at the optimum salinity condition of each surfactant in the mixture onto the SNP's surface were 1.4, 7.3 and 19.4 molecule/nm2 for the DODS, Carboxylate and AOT surfactants, respectively;; the calculated total surfactant adsorption was 2.6 mg surfactant/mg nanoparticles. While in the presence of SNP, the surfactant adsorption of the ternary surfactant foam system onto the sand surface was significantly reduced by 16.2% at 200 psi and 60 °C when compared with the neat ULIFT foam system. It was remarkably noted that the adsorption of the surfactant onto the SNP surface could result in a reduction of surfactant adsorption onto the sand surface. The oil recovery performance in the core flood by ULIFT foam was the greatest with 43% of Original Oil in Place (OOIP), and it further increased by 13% in the presence of 200 ppm SNP. In addition, the stress and viscosity of ULIFT microemulsion significantly decreased with SNP. This suspension exhibited the most non-Newtonian behavior with shear-thinning behavior over different ranges of shear rate. Therefore, SNP-ULIFT foam with the appropriate surfactant selection was a successful method for improving oil recovery performance.

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Study on the mechanism of W/O emulsion flooding to enhance oil recovery for heavy oil reservoir

Ziqi SunWanfen PuRenbao Zhao

12页

查看更多>>摘要：W/O emulsion is able to effectively improve the sweep volume and oil recovery factor during the waterflooding due to its strong mobility control ability, it has a great EOR appliance for heavy oil reservoirs. In this study, emulsion stability, droplet size distribution (DSD) and rheological behavior at different water content and salinity were investigated. Then core flooding experiments was conducted to study the oil displacement efficiency of W/O emulsion formed at different water content, and a visual micromodel was designed to observe the mechanisms of W/O emulsion flooding at the pore-throat scale. Results showed that W/O emulsion had the characteristics of the pseudoplastic fluid, exhibiting shear thinning behavior. Emulsion stability and DSD uniformity became worse with the increment of water content. Emulsion viscosity increased with water content varying from 20% to 40%, and then decreased as water content rose from 40% to 90%. Whereas Emulsion stability decreased slightly with the salinity increasing due to its high content of polar components inherent in heavy crude oil. The piston-like displacement could be formed due to its high mobility control ability caused by high viscosity. Meanwhile, the adverse effects caused by formation heterogeneity and viscosity fingering could be inhibited. After subsequent water breakthrough, emulsion droplets produced viscoelastic deformation during waterflooding. The emulsification carrying-on, block, and drag effect were the main mechanism of W/O emulsion flooding at the pore level. The findings of this study are significant for the enhanced oil recovery in heterogeneous heavy oil reservoirs.

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NSTL

Flow and heat transfer of nitrogen during liquid nitrogen fracturing in coalbed methane reservoirs

Haitao WenRuiyue YangZhongwei Huang

14页

查看更多>>摘要：Liquid nitrogen (LN2) fracturing has the potential to induce complex fracture networks, avoid formation damage, and eliminate water consumption. However, the flow and heat transfer of nitrogen in fractures and its effect on the fracture generation during LN2 fracturing have not been studied, and the fracturing mechanism remains unclear. In this paper, the nitrogen flow during LN2 fracturing in a straight fracture was simulated. First, a 3D unsteady-state fluid flow and heat transfer model for LN2 fracturing in coalbed methane (CBM) reservoir was developed, which considered the phase transition of nitrogen, thermophysical properties variation of coal and the heat transfer between nitrogen and formation. This model was then validated against published analytical solutions. Subsequently, the model was applied to elucidate the phase distribution of nitrogen and its influence on fracture generation. Finally, the factors that affect the flow and heat transfer of nitrogen were analyzed. The results showed that the nitrogen at the fracture tip was in a supercritical state. Thermal stress had minor effects on the propagation of the main fracture. In addition, fracture aperture, injection velocity, reservoir temperature, injection fluid temperature, fracture propagation pressure and coal cleat porosity could affect the effectiveness of LN2 fracturing in a coal seam. The main findings of this study are the keys to the research of liquid nitrogen fracturing mechanisms in CBM reservoirs.

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Seismic random noise suppression by using deep residual U-Net

Ming ChengXintong DongTie Zhong

12页

查看更多>>摘要：Pre-stack seismic denoising is one of most important processing steps in seismic exploration, which can significantly enhance the signal-to-noise ratio (SNR) and resolution of real seismic data. Seismic random noise often presents some complicated characteristics (non-gaussian, non-stationary, non-linear) and may overlap with desired signals in frequency domain. Thus, we need to explore the corresponding approach to attenuate the unwanted random noise and simultaneously recover the signals. Recently, some methods based on convolutional neural network (CNN) have shown excellent performance in seismic data denoising. These CNN-based denoising methods can learn the potential features of labeled data, thereby establishing the mapping relationship between noisy seismic data and signals. However, these existing CNN-based methods only consider the single-scale potential features and neglect some useful multiscale features, leading to their performance degradation when processing some seismic data with low SNR. In view of above drawback, we propose a novel CNN by introducing the residual theory and reconstruction block into the conventional U-Net, called deep residual U-Net (DRUN). In DRUN, some residual blocks are utilized to obtain the multiscale features of noisy seismic data and the followed reconstruction block can incorporate features of different scales, thereby distinguishing signals and random noise. Both the synthetic and field seismic data are processed to verify the effectiveness of DRUN. Compared with the original U-Net, the experimental results demonstrate that the proposed DRUN has superiority in noise attenuation and signal preservation.

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Experimental analysis and model evaluation of gas-liquid two phase flow through choke in a vertical tube

Chuan XieXiaoping LiYonghui Liu

28页

查看更多>>摘要：Downhole chokes have been extensively implemented in gas and oil fields to improve well performance and facilitate equipment/chemical cost savings. Existing models have been developed based on wellhead choke data. However, compared with a horizontal pipe, vertical two-phase flow presents different flow behavior and patterns. Therefore, the flow patterns should be considered to evaluate the performance of the models for predicting the downhole choke flow rate. In this study, 40 data points were tested on both vertical and horizontal tubes with 4-mm chokes. Moreover, 350 data points (Appendix) were tested on a vertical tube with four choke sizes (2, 4, 8, and 12 mm). Flow patterns, pressure, and mass flow rates were measured and analyzed. From the results of comparative analysis, significant discrepancies between vertical and horizontal evaluation results were reported. The results demonstrated that the downhole chokes changed the flow pattern downstream of chokes, improved the stability of p_d, and prevented the liquid phase downstream of chokes from falling to the upstream. The slug-churn flow transition boundary was accurately predicted by Taitel correlation, and the churn-annular flow transition boundary moved leftward with an increase in pressure. Under the critical flow condition, the Ashford model (RMSE = 0.005 kg/s and R2 = 0.92), Sachdeva model (RMSE = 0.007 kg/s and R2 = 0.80), and Al-Safran model (RMSE = 0.004 kg/s and R2 = 0.96) achieved the highest prediction accuracies for slug, churn, and annular flow, respectively. Based on 170 subcritical flow data points, the Perkins model (RMSE = 0.007 kg/s and R2 = 0.99), Ashford model (RMSE = 0.009 kg/s and R2 = 0.84), and Sachdeva model (RMSE = 0.009 kg/s and R2 = 0.76) are recommended for slug, churn, and annular flow, respectively.

原文链接:

NSTL