| 摘要: |
| 目的 鄂尔多斯盆地长7致密砂岩储层岩石致密、非均质性强,孔喉分选性及连通性较差。前期常规压裂工艺改造手段单一,裂缝欠发育的致密储层改造效果不佳。方法 根据量纲分析法(π定理)优化了物理模拟实验相似准则设计思路,设计了等比例缩小的压裂裂缝起裂及延伸模拟系统。利用大尺寸真三轴模拟实验系统,系统开展了30 cm× 30 cm× 30 cm致密砂岩露头岩样水力压裂模拟实验。利用三维扫描仪量化评价压裂裂缝改造面积,结合岩体破裂时的实验泵压峰值,揭示裂缝起裂及延伸规律。结果 量化了天然裂缝及弱面、应力差、压裂液体类型和施工排量条件下压裂裂缝起裂压力及其改造面积,揭示了地质工程因素对压裂裂缝延伸行为的影响规律,明确了地质工程参数对压裂裂缝延伸及复杂缝网形成的影响程度。结论 天然裂缝及弱面发育、低应力差、低黏滑溜水和高排量是获得复杂裂缝形态的有利因素,为研究区块体积压裂工艺试验进行了实验佐证和理论依据。建议采用“大液量、大排量、扩大波及体积”为主的体积压裂思路及工艺技术,以获得复杂缝网的改造目标。 |
| 关键词: 致密砂岩油藏 真三轴 大物模 体积压裂 裂缝扩展 |
| DOI：10.3969/j.issn.1007-3426.2023.03.017 |
| 分类号: |
| 基金项目:国家自然科学基金“超深裂缝地层溢流多相流动机理及气体侵入类型识别研究”(52274001)；中石化科技部项目“川西中浅层致密砂岩气藏体积压裂关键技术”(P22047) |
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| Simulation experiment of fracture initiation and propagation of hydraulic fracturing with true triaxial large physical model |
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Kong Xiangwei1, Yan Rentian2, Zhang Siqi3, Yuan Qinghong4, Chen Qing1, Xu Hongxing5
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1. School of Petroleum Engineering, Yangtze University, Wuhan, Hubei, China;2. Development Division of PetroChina Southwest Oil and Gasfield Company, Chengdu, Sichuan, China;3. Research Institute of Natural Gas Technology, PetroChina Southwest Oil and Gasfield Company, Chengdu, Sichuan, China;4. CNPC Dagang Oilfield Group Engineering Construction Co., Ltd, Tianjin, China;5. CCDC Changqing Down Hole Technology Company, Xi'an, Shaanxi, China
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| Abstract: |
| Objective The Chang 7 tight sandstone reservoir in Ordos Basin is characterized by tight rock, strong heterogeneity and poor pore throat sorting and connectivity. In the early stage, the conventional fracturing technology transformation methods are single, and the transformation effect of tight reservoirs with underdeveloped fractures is poor. Methods According to the dimensional analysis method (π theorem), the design idea of similarity criteria for physical simulation experiment was optimized, and the simulation system of fracture initiation and extension with equal proportion reduction was designed. Using the large scale true triaxial simulation test system, 30 cm × 30 cm × 30 cm tight sandstone outcrop sample hydraulic fracturing physical simulation experiment was carried out. According to the experimental pump pressure peak value during rock mass fracture, the three-dimensional scanner was used to quantitatively evaluate the fracture reconstruction area and reveal the fracture initiation and extension rules. Results The simulation experiment has quantified the fracturing fracture initiation pressure and reconstruction area under the conditions of fracturing fluid type, stress difference, natural fracture and weak surface and construction displacement. It has revealed the influence rule of geological engineering factors on the fracturing fracture extension behavior, and clarified the influence degree of geological engineering parameters on the fracturing fracture extension and complex fracture network formation. Conclusion sThe research showed that low stress difference, weak surface development of natural fractures and low viscosity slippery water were favorable factors for obtaining complex fracture morphology, which provided experimental evidence and theoretical basis for the study of block volume fracturing technology tests. It is suggested to adopt the volume fracturing idea and technology of "large fluid volume, large displacement and expanded swept volume" to achieve the transformation goal of complex fracture network. |
| Key words: tight sandstone oil reservoir true triaxial large physical model volume fracturing fracture propagation |
