Geoenergy Science and Engineering最新文献

{"title":"Numerical study on the effect of discontinuous proppant pumping on the proppant distribution and fracture conductivity","authors":"Xiyu Chen,&nbsp;Jingze Li,&nbsp;Yongming Li,&nbsp;Jinzhou Zhao,&nbsp;Tai Chang","doi":"10.1016/j.geoen.2024.213494","DOIUrl":"10.1016/j.geoen.2024.213494","url":null,"abstract":"<div><div>The pump schedule with intermittent injection of proppant has been adopted in hydraulic fracturing of oilfield, with an expectation for its ability to enhance the fracture conductivity and reduce the usage of proppant, like the technology named as channel fracturing. The industrial demand has stimulated many scholars to carry out a series of researches related to the performance of discontinuous proppant pumping and obtained favorable feedbacks. However, how do different proppant schemes quantify their impact on the fracture conductivity are still unclear and this leads to challenges for optimization of such schemes. Therefore, in this paper, a planar 3D fracturing model with fluid-solid coupling is presented to simulate the fracturing process by adopting discontinuous proppant pumping, for quantificationally estimating the fracturing performance. First, thirteen groups of comparable cases were elaborately designed by varying the treatment parameters respectively. Subsequently, these numerical results were analyzed to discuss in detail the effects of proppant usage amount, particle size, volume fraction and pump schedule on the proppant distribution and conductivity within the fracture. An interesting insight is found that a reducing of proppant usage by about 20% with a proper scheme can still maintain enough high conductivity without significant damage of flow path. In the case for using relatively small to medium-sized proppant, a more aggressive proppant scheme is recommended to enhance the fracture conductivity. Also, intermittent proppant pumping with a higher frequency is proposed especially in the case of using large-sized proppant, as its effectiveness for profitably adjusting the proppant distribution and increasing the median conductivity. This study provides useful guidance for optimization design of hydraulic fracturing.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213494"},"PeriodicalIF":0.0,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of failure modes and impact resistance factors of PDC cutters","authors":"Fangyuan Shao ,&nbsp;Guodong Ji ,&nbsp;Li Liu ,&nbsp;Wei Liu ,&nbsp;Xiaoao Liu ,&nbsp;Xiang Yan ,&nbsp;Jiusen Wei ,&nbsp;Yu Zhang ,&nbsp;Yuqi Sun","doi":"10.1016/j.geoen.2024.213462","DOIUrl":"10.1016/j.geoen.2024.213462","url":null,"abstract":"<div><div>The service life of PDC cutters directly affects the overall drilling performance. In hard and heterogeneous formations, PDC cutters often fail prematurely due to dynamic impacts, leading to short footage and slow penetration rates. Enhancing the dynamic impact resistance of PDC cutters is crucial for achieving one-run drilling and reducing costs. This paper systematically studies the main factors influencing and optimizing the impact resistance of PDC cutters. First, the failure modes of hundreds of returned PDC drill bits were statistically analyzed, revealing that dynamic impact failure, wear failure, thermal damage, and erosion are the primary failure modes. Among these, dynamic impact failure is the most prevalent, with dynamic impact load being the main cause. Following the successful practices of leading international drill bit companies, a set of dynamic impact test and evaluation devices for PDC cutters was designed, and corresponding testing standards were established. Based on this, 19 types of PDC cutters were tested for impact resistance, exploring the effects of cutter diameter, diamond layer thickness, chamfer, cobalt removal, and cutter design on impact resistance. An optimized design methodology to enhance impact resistance was summarized, leading to the proposal of a new arch-axe cutter design. Indoor impact test data verified the superiority of this cutter. The research results indicate that cutter design (non-standard cutters) can significantly improve the dynamic impact resistance of PDC cutters. Additionally, increasing the cutter diameter and chamfer size while reducing the diamond layer thickness also enhances the dynamic impact resistance of PDC cutters. Through the optimization of the arch-ridge design, the independently developed arch-axe cutter improved the dynamic impact resistance by 106.45% and 71.43% compared to flat circular cutters and axe-shaped cutters, respectively.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213462"},"PeriodicalIF":0.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Techno-economic assessment of surfactant Huff-n-Puff EOR in shale plays via multi-objective optimization","authors":"Chunhua Lu ,&nbsp;Miao Zhang ,&nbsp;Qian Sun ,&nbsp;Guangquan Zhang ,&nbsp;Hanqiao Jiang ,&nbsp;Junjian Li","doi":"10.1016/j.geoen.2024.213449","DOIUrl":"10.1016/j.geoen.2024.213449","url":null,"abstract":"<div><div>Surfactant Huff-n-Puff (HnP) has proven effective for enhanced oil recovery (EOR) in unconventional petroleum reservoirs. Due to the high cost of surfactant injectants, a comprehensive techno-economic analysis is crucial for optimizing development strategies. This study focuses on the Jimusar J305 shale oil reservoir, employing a Pareto-optimal multi-objective optimization (MOO) model to identify the best injection-production strategies for surfactant HnP. Using crude oil recovery and economic performance as objectives, the model combines numerical simulations with the multi-objective particle swarm optimization (MOPSO) algorithm. A decision-making protocol based on Pareto solutions is proposed to balance objectives, alongside an EOR mechanism analysis. Results show the net present value (NPV) improved from −2.98 million to +3.48 million USD without reducing oil recovery, indicating that different surfactant HnP strategies can achieve similar recovery outcomes but vary significantly in profitability. Optimal project design involves adjusting surfactant volume to reverse rock wettability and balancing injection rates and concentrations to enhance production while controlling costs.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213449"},"PeriodicalIF":0.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamics study of self-pulling & self-rotating jet drill bit in natural gas hydrate reservoirs radial horizontal well drilling","authors":"Yandong Yang,&nbsp;Qingchao Li,&nbsp;Yuqiang Xu,&nbsp;Jinsong Huang","doi":"10.1016/j.geoen.2024.213490","DOIUrl":"10.1016/j.geoen.2024.213490","url":null,"abstract":"<div><div>Deep-sea natural gas hydrate is rich in resources and has high energy density, making it a clean energy source with great development prospects, compared with the conventional oil and gas formations, hydrate reservoirs are shallow, with low hardness and uniaxial compressive strength. However, due to temperature changes, conventional drilling can cause hydrates to decompose, leading to wellbore instability, which will lead to wellbore instability. In view of the problem of increasing the rate of penetration (ROP), horizontal wellbore formed by high pressure jet is considered an efficient method for natural gas hydrate drilling, and the drill bit is the core equipment to form horizontal wellbore in the reservoir. Therefore, a self-pulling and rotating drill bit is proposed, the basic principle of that is when the drill bit breaks the rock at the bottom of the well, the front nozzle provides jet rock-breaking energy, the rear nozzle generates rotational torque, overcoming the friction torque between the rotating drill bit and the shaft, providing rotational energy for the drill bit, realize the movement of self-rotating and move forward while drilling. Therefore, three parameters are mainly evaluated in this paper, the self-pulling force, the angular momentum and jet pressure, the self-pulling force is for the forward moving of the bit, the angular momentum is for the stable rotating of the bit, and the jet pressure is for the natural gas hydrate drilling. Meanwhile, three different structural bits are analyzed from the influences of inlet flow, outlet size on the self-pulling force, jet pressure and flow ratio of front and rear nozzles. The results demonstrate that self-pulling force and jet pressure of bit with four front nozzles is the best at the same conditions, and the flow ratio of front and rear nozzles is depended on the structure of the bit; with the increasing of the inlet velocity, the self-pulling force and the jet pressure increases nonlinearly, and the angular momentum increases linearly. The equivalent outlet size has remarkable influence on the jet pressure, with increase of the front and rear nozzle size, the self-pulling force and jet pressure is decreases greatly. Moreover, the wellbore hole forming ability of the jet bit under different jet distances is discussed, shows that erosion wellbore hole forming ability is best at the nozzle outlet. This research provides an effective and feasible solution for the drilling of the hydrate radial horizontal wells.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213490"},"PeriodicalIF":0.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of recoverable reserves based on dynamic data for horizontal wells in unconventional oil reservoir","authors":"Linlin Zhang ,&nbsp;Fengpeng Lai ,&nbsp;Xitong Xu ,&nbsp;Xuanrui Zhang","doi":"10.1016/j.geoen.2024.213493","DOIUrl":"10.1016/j.geoen.2024.213493","url":null,"abstract":"<div><div>Unconventional reservoirs are often exploited by horizontal well volumetric fracturing. Recoverable reserves are an important basis for evaluating the development effect of oil reservoirs. In this study, an evaluation index of recoverable reserves was proposed which based on the mathematical statistics method. A mathematical model for the index and the standardized calculation process were established. The dynamic data in the study was from the RA tight reservoir of Songliao basin. The results show that: (1) Horizontal wells production can be categorized into three distinct groups based on daily oil production and cumulative oil production (N_p), showing no obvious \"L\"-shaped decrease. (2) A power function is presented by the correlation between N_p logarithm (log<em>N</em>_<em>p</em>) and production time, with a distinct inflection point in the curve. As the evaluation index of recoverable reserves, the N_p corresponding to the inflection point is taken. (3) After verification, the derivative value of log<em>N</em>_<em>p</em> corresponding to the inflection point is approximately 0, and the derivative parameter m represents the characteristics of different regions. Statistically, the study area m is 0.0003. (4) The recoverable reserves evaluation indexes of all known horizontal wells that can reflect the real production capacity were calculated. The recoverable reserves of the three blocks in the study area were successively S1 block, S3 block and S2 block from high to low. (5) According to the relationship between cumulative oil production, initial daily production and the evaluation index, the evaluation index is only suitable for the characterization of recoverable reserves in the middle and late production of tight oil wells, but not suitable for the characterization of recoverable reserves in the early production of wells.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213493"},"PeriodicalIF":0.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and evaluation of new type plant extraction corrosion inhibitor","authors":"Zhi Zhang,&nbsp;Xiaoxiao Feng","doi":"10.1016/j.geoen.2024.213495","DOIUrl":"10.1016/j.geoen.2024.213495","url":null,"abstract":"<div><div>The use of corrosion inhibitors in the development of oil and gas fields is an important means of effectively preventing metal corrosion, at present, the green growth of the oil and gas industry requires low-toxicity, low-residue, easy-to-post-treatment and other environmentally friendly corrosion inhibitors, however, most industrially used corrosion inhibitors such as mercury salts quaternary ammonium salts, and imidazolines are toxic to some degree. In this paper, a plant extract corrosion inhibitor was synthesized, firstly, the purple sweet potato extract was extracted by ethanol, and then the purple sweet potato extract and alkyl halide such as methane were used to produce the purple sweet potato corrosion inhibitor through condensation extraction and other processes, and the corrosion inhibitory performance of the inhibitor was evaluated by the loss-in-weight method, scanning electron microscopy, polarization curves, and impedance spectroscopy. The results show that there is a certain inhibition effect on N80 steel in the simulated stratum water environment, and the retardation rate can reach 91.38% in the gas phase, and the corrosion product morphology and chemical elements on the surface of N80 steel specimens were characterized by SEM, EDS, and it can be observed that a relatively dense protective film was formed after adding purple sweet potato corrosion inhibitor, and the corrosion inhibition rate can be known according to the weightlessness curve, Tafel curve and impedance curve. The corrosion inhibition rate increases with the increase of corrosion inhibitor concentration.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"245 ","pages":"Article 213495"},"PeriodicalIF":0.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of wax deposition phase change law and main influencing factors in oil-water mixed transportation pipeline under unsteady working conditions","authors":"Wei Sun ,&nbsp;Bingxue Liu ,&nbsp;Xudong Zhang ,&nbsp;Lixin Zhao ,&nbsp;Qinglin Cheng ,&nbsp;Zhihua Wang","doi":"10.1016/j.geoen.2024.213475","DOIUrl":"10.1016/j.geoen.2024.213475","url":null,"abstract":"<div><div>With the middle and late stage of oilfield exploitation, the water content is rising, and at the same time, the wax deposition in the mixed pipeline causes the effective circulation area of the pipeline to decrease, the energy loss to increase, and even the pipeline is blocked in serious cases. In this paper, the effects of oil temperature, velocity and water content on the phase change behavior of oil-water two-phase wax precipitation are comprehensively considered, and a three-dimensional theoretical model of wax precipitation process in the pipeline is established to simulate the flow and heat transfer process from the wellhead to the metering room, and the change of wax deposition amount and the distribution of deposition layer in the pipeline are creatively studied from the perspective of time and space. The initial area of wax precipitation, the fluctuating area of wax deposit distribution and the stable thickening area of wax deposit distribution are put forward. By using multivariate nonlinear regression method, the model of main influencing factors in each region is established, and the influence mechanism between wax deposition thickness and liquid content in the pipe and fluid temperature, velocity and water content in each season is quantitatively characterized. The results show that in the initial area of wax precipitation, the phase transition phenomenon of oil wax precipitation near the wall is the most intense, but no obvious deposition layer will be formed in a short time. In the fluctuation area of wax deposition distribution, there is a continuous water phase near the wall, which distorts and reduces the diffusion path of dissolved wax, resulting in sheet-like accumulation of deposition layer. The oil-water flow state in the thickening area with stable distribution of wax deposition is smooth stratified flow, and the thickness of deposition layer reaches a stable value. At the same time, the annular flow pattern appears in the elbow and vertical pipeline, and the precipitated wax crystals are suspended in the oil to form solid and liquid phases, and no obvious wax deposition layer is formed near the wall.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"245 ","pages":"Article 213475"},"PeriodicalIF":0.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation of solid diverting particles transport and plugging in large-scale hydraulic fracture","authors":"Qianli Lu ,&nbsp;Hang Zhang ,&nbsp;Jianchun Guo ,&nbsp;Xinwei Gong ,&nbsp;Le He ,&nbsp;Li Zhan","doi":"10.1016/j.geoen.2024.213481","DOIUrl":"10.1016/j.geoen.2024.213481","url":null,"abstract":"<div><div>Diversion technology, also known as temporary plugging technology, has become an integral part of hydraulic fracturing in unconventional reservoirs. The solid diverting particles are a common type of chemical diverting agents used in horizontal well multistage fracturing. The transport and plugging of solid diverting particles within the fractures are crucial physical processes in the far-field diversion technology. In this study, in order to clarify the formation of the plugging layer by solid diverting particles in large-scale hydraulic fracture and to offer insights for the quantitative optimization of far-field diversion technology (FFD), an enhanced simplified two-fluid model within the Euler-Euler framework is employed to simulate the transport and plugging process of solid diverting particles within the fracture. And the numerical schemes of the front settlement region, the plugging layer formation region and the rear settlement region are also optimized. The proposed model is verified through comparison with experimental results from visual fracture test device. Based on the numerical results across various particle, pumping and fracture parameters, our findings indicate that: (1) The duration required to form a complete plugging layer can be reduced to 3%∼20% by increasing injection concentration, injection rate, and fracturing fluid viscosity; (2) Increasing the injection concentration (from 10kg/m³ to 30kg/m³) significantly enhances the length of the plugging layer by about 1∼16 times, compensating for the inability to achieve a complete plugging layer with smaller particle sizes. Merely increasing the injection rate alone (from 0.35m³/min to 0.80m³/min) does not remedy the inability of small particles to form a complete plugging layer under identical plugging conditions. Excessive fracturing fluid viscosity (higher than 6mPa·s) impedes the formation of a complete plugging layer with smaller particles. High fracturing fluid leak-off rate (higher than 2.5×10^-⁷m/s) markedly reduces the length of the plugging layer by about 37%∼44%; (3) Achieving a high close packing degree of particles within the plugging layer is facilitated by increasing injection concentration, increasing injection rate, and reducing fluid viscosity; (4) The abrupt variation in fracture width or height along the fracture length affects up to about 18% of the length of the plugging layer at the top of fracture. To ensure large length of the plugging layer at the top of fracture and high close packing degree of particles within the plugging layer, we recommend injection concentration above 10kg/m³, fracturing fluid viscosity below 6mPa·s, and injection rate exceeding 0.35m³/min. For particle size less than 1.8mm, we suggest injection concentration above 20kg/m³, and fracturing fluid viscosity not exceeding 3mPa·s.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213481"},"PeriodicalIF":0.0,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heavy Oil—Solid separation mechanism opportunities and challenges: From interfacial Concept","authors":"Wenjuan Wang ,&nbsp;Yuting Hu ,&nbsp;Zihui Li ,&nbsp;Zhongchi Wu ,&nbsp;Jiacheng Li,&nbsp;Gaobo Yu,&nbsp;Jinjian Hou","doi":"10.1016/j.geoen.2024.213482","DOIUrl":"10.1016/j.geoen.2024.213482","url":null,"abstract":"<div><div>In recent years, conventional oil has played a crucial role in industrial production and daily life. However, as oil resources continue to decline, the development of unconventional oil resources has become an important research focus. Among these resources, advancements in heavy oil-solid separation technology are essential for improving recovery rates and economic efficiency. This paper focused on unconventional heavy oil and discussed in detail the characterization techniques for oil-solid separation, including AFM, QCM-D, SFA and FTIR. It also covered various separation techniques such as HWBE, solvent extraction, and pyrolysis. Due to the unclear mechanisms of heavy oil-solid separation, this review explored how heavy oil could be effectively separated from host solids to better understand the heavy oil-solid separation mechanisms. Finally, it explored the current challenges and future research directions, offering valuable insights and theoretical support for enhancing the practical application of heavy oil separation processes.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213482"},"PeriodicalIF":0.0,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental evaluation of temporary plugging performance and mechanism analysis of degradable preformed particle gel based on NMR technology","authors":"Daoyi Zhu,&nbsp;Hongjun Zhang,&nbsp;Junhui Qin,&nbsp;Qi Zhao,&nbsp;Guiqi Wang,&nbsp;Zhenghao Su,&nbsp;Chenyang Shi","doi":"10.1016/j.geoen.2024.213480","DOIUrl":"10.1016/j.geoen.2024.213480","url":null,"abstract":"<div><div>Utilizing chemical temporary plugging systems to further increase the stimulated reservoir volume (SRV) and improve oil recovery (IOR) has become a hot topic in the current petroleum industry. Pre-formed gel particles (PPG) possess excellent swelling properties and can form high-strength plugging in high-permeability channels. In addition, degradable pre-formed gel particles (DPPG) further exhibit self-degradation characteristics and excellent temporary plugging and fluid diverting performance. In our previous studies, we examined the temporary plugging mechanisms of DPPG prepared with different molecular weight (MW) of crosslinking agents (PEGDA) through bottle tests and core displacement experiments. However, the microscopic swelling mechanism and temporary plugging mechanism in pore throats of reservoir cores are still unclear. In this paper, comprehensive research was conducted on the microscopic temporary plugging mechanism of DPPG prepared with different MW crosslinking agents using both and method. Results showed that DPPG with different compositions had different micro-swelling performance. NMR-<em>T</em>₂ analysis for bottle test showed that DPPG-M1 (with the smallest MW of crosslinking agent) gradually decreased in nuclear signal during the water absorption and swelling process, and had the largest swelling volume and swelling rate. On the other hand, DPPG-M5 (with the largest MW of crosslinking agent) exhibited a slow diffusion process of surface water towards the nucleus, resulting in the smallest swelling volume and swelling rate. However, its complete degradation time was longer. Moreover, the NMR <em>T</em>₂ (i.e., spin-spin relaxation time) results of the cores in the dynamic temporary plugging experiment showed that the decrease of the MW of the crosslinking agent enhanced the plugging performance, but with less damage to the formation. The MRI images confirmed that DPPG-M5 had better injection capability in the core and caused greater damage to the core. The research results of this study showed that NMR technology can reveal the temporary plugging mechanism of DPPG from a micro-level perspective.</div></div>","PeriodicalId":100578,"journal":{"name":"Geoenergy Science and Engineering","volume":"244 ","pages":"Article 213480"},"PeriodicalIF":0.0,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}