酸作用下碳酸盐岩刻蚀形貌及力学性能研究  

Etching morphology and mechanical properties of carbonate rocks under acid

作　　者：张文 梁利喜[1] 刘向君[1] 熊健[1] 张忆南 ZHANG Wen;LIANG Lixi;LIU Xiangjun;XIONG Jian;ZHANG Yinan(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500

出　　处：《油气藏评价与开发》2024年第2期247-255,共9页Petroleum Reservoir Evaluation and Development

基　　金：西南石油大学“非常规地层岩石物理青年科技创新团队”(2018CXTD11)。

摘　　要：碳酸盐岩在化学和力学作用下结构及力学特征是该类储层酸压技术有效性评价的重要研究课题。以海相碳酸盐岩为研究对象,开展了20%HCl胶凝酸对碳酸盐岩结构和力学性能影响的室内实验研究。基于矿物组成,将碳酸盐岩划分为灰岩、含云质灰岩、含灰质云岩和云岩4种类型,相对于灰岩的均匀刻蚀,酸在含云质灰岩表面选择性刻蚀,形成蚓蚀刻槽,而含灰质云岩和云岩则以点状刻蚀和沿着结构面侵蚀为主。酸作用前碳酸盐岩具有基质强度主导的剪切破坏特征,而酸作用后改变了岩石内部结构,导致碳酸盐岩更易在拉张应力作用下发生破坏,更容易劈裂破坏或沿结构面破坏。酸作用后碳酸盐岩的宏观强度降幅远大于基质强度降幅,酸液通过侵入岩石内部,在岩石内部形成更多微观缺陷,表现为峰值应力时弹性能占比降低和耗散能占比增加,因此其宏观力学性能劣化是基质强度劣化和内部结构改变共同作用的结果。研究结论对于碳酸盐岩现场酸压实践以及后续生产方案制定提供一定指导。The structural and mechanical characteristics of carbonate rock under the action of chemistry and mechanics is an important research topic for the evaluation of the effectiveness of acid fracturing technology in this kind of reservoir.This research focused on the impact of 20%HCI gelled acid on the structural and mechanical properties of carbonate rocks,categorized into four types based on their mineral composition:limestone,dolomite-bearing limestone,limestone-bearing dolomite,and dolomite.The experiments revealed distinct reactions of these rock types to acid exposure.Limestone exhibited uniform etching,while dolomite-bearing limestone showed selective etching,creating wormhole-like grooves.Limestone-bearing dolomite and dolomite predominantly experienced point etching and erosion along structural planes.Initially,the shear failure of carbonate rocks was primarily governed by matrix strength.However,acid treatment altered their internal structure,making them more susceptible to tensile stress damage,leading to potential splitting or destruction along structural planes.Notably,the reduction in the macroscopic strength of the carbonate rocks post-acid treatment was significantly greater than the decrease in matrix strength alone.The invasion of acid liquid into the rocks introduced additional microscopic defects,evidenced by a reduced proportion of elastic energy and an increased proportion of dissipated energy at peak stress levels.This suggests that the macroscopic mechanical property deterioration results from both matrix strength weakening and internal structural changes.These findings offer valuable insights for field acid fracturing operations in carbonate rock reservoirs and aid in the planning of subsequent production strategies。

关 键 词：碳酸盐岩 胶凝酸 矿物组成 刻蚀形貌 力学性能 

分 类 号：TE122[石油与天然气工程—油气勘探]