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Zhao H, Li W, Cai M, Ma B, Xie X, Zou L, Liu Y. Study on rock fracture mechanism and hydraulic fracturing propagation law of heterogeneous tight sandstone reservoir. PLoS One 2024; 19:e0303251. [PMID: 39093902 PMCID: PMC11296645 DOI: 10.1371/journal.pone.0303251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 04/22/2024] [Indexed: 08/04/2024] Open
Abstract
Hydraulic fracturing technology is an effective way to develop tight sandstone reservoirs with low porosity and permeability. The tight sandstone reservoir is heterogeneous and the heterogeneity characteristics has an important influence on fracture propagation. To investigate hydraulic fracture performance in heterogeneous tight reservoir, the X-ray diffraction experiments are carried out, the Weibull distribution method and finite element method are applied to establish the uniaxial compression model and the hydraulic fracture propagation model of heterogeneous tight sandstone. Meanwhile, the sensitivity of different heterogeneity characterization factors and the multi-fracture propagation mechanism during hydraulic fracture propagation is analyzed. The results indicate that the pressure transfer in the heterogeneous reservoir is non-uniform, showing a multi-point initiation fracture mode. For different heterogeneity characterization factors, the heterogeneity characteristics based on elastic modulus are the most sensitive. The multi-fracture propagation of heterogeneous tight sandstone reservoir is different from that of homogeneous reservoir, the fracture propagation morphology is more complex. With the increase of stress difference, the fracture propagation length increases. With the increase of injection rate, the fracture propagation length increases. With the increase of cluster spacing, the propagation length of multiple fractures tends to propagate evenly. This study clarifies the influence of heterogeneity on fracture propagation and provides some guidance for fracturing optimization of tight sandstone reservoirs.
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Affiliation(s)
- Huan Zhao
- Northeast Petroleum University, College of Petroleum Engineering, Daqing, China
- Daqing Oilfield Co Ltd, Daqing, China
- National Key Laboratory of Continental Shale Oil, Daqing, China
- National Engineering Research Center of Oil & Gas Drilling and Completion Technology, Beijing, China
| | - Wei Li
- Northeast Petroleum University, College of Petroleum Engineering, Daqing, China
- National Key Laboratory of Continental Shale Oil, Daqing, China
- National Engineering Research Center of Oil & Gas Drilling and Completion Technology, Beijing, China
| | - Meng Cai
- Northeast Petroleum University, College of Petroleum Engineering, Daqing, China
- National Engineering Research Center of Oil & Gas Drilling and Completion Technology, Beijing, China
- Research Institute of Oil Production Engineering of Daqing Oilfield Co Ltd, Daqing, China
- Heilongjiang Provincial Key Laboratory of Oil and Gas Reservoir Stimulation, Daqing, China
| | - Biao Ma
- Northeast Petroleum University, College of Petroleum Engineering, Daqing, China
| | - Xiaorui Xie
- Northeast Petroleum University, College of Petroleum Engineering, Daqing, China
- National Key Laboratory of Continental Shale Oil, Daqing, China
| | - Linhao Zou
- Northeast Petroleum University, College of Petroleum Engineering, Daqing, China
- National Key Laboratory of Continental Shale Oil, Daqing, China
| | - Yapeng Liu
- Northeast Petroleum University, College of Petroleum Engineering, Daqing, China
- National Key Laboratory of Continental Shale Oil, Daqing, China
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Jiang W, Lv W, Jia N, Cheng K, Wan Y, Wang K. Molecular Insights into Soaking in Hybrid N 2-CO 2 Huff-n-Puff: A Case Study of a Single Quartz Nanopore-Hydrocarbon System. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:14922-14940. [PMID: 38990799 DOI: 10.1021/acs.langmuir.4c00989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
Hybrid N2-CO2 huff-n-puff (HnP) has been experimentally demonstrated to be a promising approach for improving oil recovery from tight/ultratight shale oil reservoirs. Despite this, the detailed soaking process and interaction mechanisms remain unclear. Adopting molecular dynamic simulations, the soaking behavior of hybrid N2-CO2 HnP was investigated at the molecular and atomic levels. Initially, the soaking process of fluid pressure equilibrium after injection pressure decays in a single matrix nanopore connected to a shale oil reservoir is studied. The study revealed that counter-current and cocurrent displacement processes exist during the CO2 and hybrid N2-CO2 soaking, but cocurrent displacement occurs much later than counter-current displacement. Although the total displacement efficiency of the hybrid N2-CO2 soaking system is lower than that of the CO2 soaking system, the cocurrent displacement initiates earlier in the hybrid N2-CO2 soaking system than in the CO2 soaking system. Moreover, the N2 soaking process is characterized by only counter-current displacement. Next, the soaking process of fluid pressure nonequilibrium before the injection pressure decays is investigated. It was discovered that counter-current and cocurrent displacement processes initiate simultaneously during the CO2, N2, and hybrid N2-CO2 soaking process, but cocurrent displacement exerts a dominant influence. During the CO2 soaking process, many hydrocarbon molecules in the nanopore are dissolved in CO2 while simultaneously exhibiting a substantial retention effect in the nanopore. After pure N2 injection, there is a tendency to form a favorable path of N2 through the oil phase. The injection of hybrid CO2-N2 facilitates the most significant cocurrent displacement effect and the reduction in residual oil retained in the nanopore during the soaking process, thus resulting in the best oil recovery. However, the increase rate in total displacement efficiencies of the different soaking systems over time (especially the hybrid N2-CO2 soaking system) was significantly larger before than after injection pressure decays. Additionally, the displacement effect induced by oil volume swelling is significantly restricted before the injection pressure decays compared to the soaking process after the injection pressure decays. This study explains the role of CO2-induced oil swelling and N2-induced elastic energy played by hybrid N2 and CO2 at different stages of the hybrid N2-CO2 soaking process before and after pressure decays and provides theoretical insights for hybrid gas HnP-enhanced recovery. These pore-scale results highlight the importance of injection pressure and medium composition during the soaking process in unconventional oil reservoirs.
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Affiliation(s)
- Wen Jiang
- College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
| | - Weifeng Lv
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- State Key Laboratory of Enhanced Oil and Gas Recovery, Beijing 100083, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
| | - Ninghong Jia
- State Key Laboratory of Enhanced Oil and Gas Recovery, Beijing 100083, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
| | - Kai Cheng
- Beijing Key Laboratory for Greenhouse Gas Storage and CO2-EOR Unconventional Petroleum Research Institute, China University of Petroleum (Beijing), Beijing 102249, P. R. China
| | - Yidi Wan
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
- School of Earth and Space Sciences, Peking University, Beijing 100871, P. R. China
| | - Kai Wang
- College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
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Yang S, Zheng K, Zhang J, Dai N, Wang L, Wang Z, Wang H, Kong X. Quantitative evaluation of acid flow behavior in fractures and optimization of design parameters based on acid wormhole filtration losses. Sci Rep 2024; 14:15799. [PMID: 38982152 PMCID: PMC11233543 DOI: 10.1038/s41598-024-66680-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 07/03/2024] [Indexed: 07/11/2024] Open
Abstract
The technique of matrix acidification or acid fracturing is commonly utilized to establish communication with natural fractures during reservoir reconstruction. However, this process often encounters limitations due to filtration, which restricts the expansion of the primary acid-etching fracture. To address this issue, a computational model has been developed to simulate the expansion of an acid-etching wormhole by considering various factors such as formation process, injection duration, pressure build-up, and time-varying acid percolation rate. By analyzing the pumping displacement of acid-etching wormholes, this model provides valuable insights into the time-dependent quantities of acid percolation. It has been revealed that the filtration rate of acid-etching wormholes is strongly influenced by pumping displacement, viscosity, and concentration of the acid fluid used in stimulation as well as physical properties of the reservoir itself. Notably, viscosity plays a significant role in determining the effectiveness of acid fracturing especially in low-viscosity conditions. Acid concentration within 15% to 20% exhibits maximum impact on successful acid fracturing while concentrations below 15% or above 20% show no obvious effect. Furthermore, it was found that pumping displacement has a major influence on effective fracturing. However, beyond a certain threshold (> 5.0 m3/min), increased pumping displacement leads to slower etching distance for acids used in construction purposes. The simulation also provides real-time distribution analysis for acidity levels within eroded fractures during matrix-acidification processes and quantifies extent of chemical reactions between acids and rocks within these fractures thereby facilitating optimization efforts for design parameters related to matrix-acidification.
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Affiliation(s)
- Sen Yang
- Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710077, China.
| | - Kaige Zheng
- Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710077, China
| | - Jian Zhang
- Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710077, China
| | - Nan Dai
- Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710077, China
| | - Lintao Wang
- Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710077, China
| | - Zeyang Wang
- Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710077, China
| | - Haojie Wang
- Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710077, China
| | - Xiangwei Kong
- School of Petroleum Engineering, Yangtze University, Wuhan, 430100, China.
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Duan Y, Li Y, Chen B, Ai C, Wu J. Preparation and performance evaluation of a novel temperature-resistant anionic/nonionic surfactant. Sci Rep 2024; 14:5710. [PMID: 38459239 PMCID: PMC10923936 DOI: 10.1038/s41598-024-56342-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 03/05/2024] [Indexed: 03/10/2024] Open
Abstract
Aiming at oil extraction from a tight reservoir, the Jilin oil field was selected as the research object of this study. Based on the molecular structures of conventional long-chain alkyl anionic surfactants, a new temperature-resistant anionic/nonionic surfactant (C8P10E5C) was prepared by introducing polyoxyethylene and polyoxypropylene units into double-chain alcohols. The resulting structures were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR), and electrospray ionization mass spectrometry (ESI-MS). Then, based on surface tension, interfacial tension, adsorption resistance, wettability, and emulsification performance tests, the performance of C8P10E5C was evaluated. The FT-IR, ESI-MS, and NMR spectra confirmed that C8P10E5C was successfully prepared. The critical micelle concentration (CMC) of C8P10E5C in water was 2.9510 × 10-4 mol/L (the corresponding mass concentration is 0.26%), and the surface tension of the aqueous C8P10E5C solution at this concentration was 30.5728 mN/m. At 0.3% concentration, the contact angle of the C8P10E5C solution was 31.4°, which is 60.75% lower than the initial contact angle. Under high-temperature conditions, C8P10E5C can still reduce the oil-water interfacial tension to 10-2 mN/m, exhibiting good temperature resistance. At 110 °C, upon adsorption to oil sand, the C8P10E5C solution could reduce the oil-water interfacial tension to 0.0276 mN/m, and the interfacial tension can still reach the order of 10-2 mN/m, indicating that C8P10E5C has strong anti-adsorption capability. Additionally, it has good emulsifying performance; upon forming an emulsion with crude oil, the highest drainage rate was only 50%. The forced imbibition oil recovery of C8P10E5C is 65.8%, which is 38.54, 24.22, and 27.25% higher than those of sodium dodecyl benzene sulfonate, alkyl polyoxyethylene ether carboxylate, and alkyl ether carboxylate, respectively.
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Affiliation(s)
- Yongwei Duan
- College of Petroleum Engineering, Northeast Petroleum University, Daqing, 163318, China
- Jilin Oilfield Oil & Gas Engineering Research Institute, Songyuan, 138000, China
| | - Yanpeng Li
- Songyuan Gas Production Plant of Jilin Oilfield Company of PetroChina, Songyuan, 138000, China
| | - Boru Chen
- Songyuan Gas Production Plant of Jilin Oilfield Company of PetroChina, Songyuan, 138000, China
| | - Chi Ai
- College of Petroleum Engineering, Northeast Petroleum University, Daqing, 163318, China.
| | - Jun Wu
- Jilin Oilfield Oil & Gas Engineering Research Institute, Songyuan, 138000, China
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Huang Y, Yao X, Dai C, Wu Y, Li L, Yuan B. A Supramolecular Reinforced Gel Fracturing Fluid with Low Permeability Damage Applied in Deep Reservoir Hydraulic Fracturing. Gels 2023; 10:2. [PMID: 38275840 PMCID: PMC10815564 DOI: 10.3390/gels10010002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 12/14/2023] [Accepted: 12/16/2023] [Indexed: 01/27/2024] Open
Abstract
Gel fracturing fluid is the optimum fracturing fluid for proppant suspension, which is commonly applied in deep reservoir hydraulic fracturing. The content of polymers and crosslinkers in gel fracturing fluid is usually high to meet the needs of high-temperature resistance, leading to high costs and reservoir permeability damage caused by incomplete gel-breaking. In this paper, a supramolecular reinforced gel (SRG) fracturing fluid was constructed by strengthening the supramolecular force between polymers. Compared with single network gel (SNG) fracturing fluid, SRG fracturing fluid could possess high elasticity modulus (G' = 12.20 Pa) at lower polymer (0.4 wt%) and crosslinker (0.1 wt%) concentrations. The final viscosity of SRG fracturing fluid was 72.35 mPa·s, meeting the temperature resistance requirement of gel fracturing fluid at 200 °C. The gel-breaking time could be extended to 90-120 min using an encapsulated gel breaker. Gel particles are formed after the gel fracturing fluid is broken. The median particle size of gel particles in the SRG-breaking solution was 126 nm, which was much smaller than that in the industrial gel (IDG) breaking fluid (587 nm). The damage of the SRG-breaking solution to the core permeability was much less than the IDG-breaking solution. The permeability damage of cores caused by the SRG-breaking solutions was only about half that of IDG-breaking solutions at 1 mD.
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Affiliation(s)
- Yongping Huang
- Shandong Key Laboratory of Oilfield Chemistry, China University of Petroleum (East China), Qingdao 266580, China; (Y.H.); (X.Y.); (Y.W.)
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China;
| | - Xinlong Yao
- Shandong Key Laboratory of Oilfield Chemistry, China University of Petroleum (East China), Qingdao 266580, China; (Y.H.); (X.Y.); (Y.W.)
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China;
| | - Caili Dai
- Shandong Key Laboratory of Oilfield Chemistry, China University of Petroleum (East China), Qingdao 266580, China; (Y.H.); (X.Y.); (Y.W.)
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China;
| | - Yining Wu
- Shandong Key Laboratory of Oilfield Chemistry, China University of Petroleum (East China), Qingdao 266580, China; (Y.H.); (X.Y.); (Y.W.)
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China;
| | - Lin Li
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China;
| | - Bin Yuan
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China;
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