海陆过渡相页岩储层液岩作用机理及钻井液体系构建  

Mechanism of Fluid Shale Interaction and Construction of Drilling Fluid System in Marine Land Transitional Shale Reservoirs

作　　者：王维[1,2] 王金堂 辛江 曹振义 林伟 刘磊 孙金声 WANG Wei;WANG Jintang;XIN Jiang;CAO Zhenyi;LIN Wei;LIU Lei;SUN Jinsheng(China United Coalbed Methane National Engineering Research Center Co.,Ltd.,Beijing 100095;PetroChina Coalbed Methane Company Limited,Beijing 100028;School of Petroleum Engineering,China University of Petroleum(East China),Qingdao,Shandong 266580)

机构地区：[1]中联煤层气国家工程研究中心有限责任公司,北京100095 [2]中石油煤层气有限责任公司,北京100028 [3]中国石油大学(华东)石油工程学院,山东青岛266580

出　　处：《钻井液与完井液》2024年第4期427-436,共10页Drilling Fluid & Completion Fluid

摘　　要：我国海陆过渡相页岩地质储量大、资源丰度高,开发前景广阔。但钻井过程中井壁极易发生掉块、坍塌,导致井壁失稳影响钻井安全。本文通过钻井岩心观察、电镜和CT扫描、X射线衍射分析等相关实验,得到储层岩样矿物组分及微观结构等特征,结果表明:页岩气储层全岩主要含石英和黏土矿物,地层黏土矿物含量高达45.7%,且黏土矿物中不含蒙脱石,高岭石含量为35%,伊/蒙混层含量为26%;岩样表面纳微米孔隙和微裂缝发育,裂缝宽度在微米级并连通多条窄裂缝;通过岩液作用后晶层间距、表面张力、线性膨胀率和裂缝扩展变化分析,海陆过渡相页岩仅发生表面水化,揭示了海陆过渡相页岩气储层岩液作用机理。优选了水基钻井液抑制剂、封堵剂与润滑剂,构建了一套海陆过渡相页岩气储层的高性能水基钻井液体系,并对其展开了室内评价。钻井液常规性能、抑制性、封堵性、润滑性评价实验结果表明,该钻井液体系抗温100℃,高温高压失水6 mL,泥页岩膨胀率为1.03%,钻井液润滑系数整体小于0.15,体系30 min的API滤失量较基浆降低40%,可对地层微裂缝实现有效封堵,且生物毒性EC50值为37260 mg/L,属于无毒级别,能够满足海陆过渡相页岩气钻井作业施工对钻井液性能的要求并进行了现场应用,封堵防塌效果良好,可有效解决海陆过渡相泥页岩井壁失稳的技术难题。China possesses abundant shale geological reserves and a high concentration of resources in the coastal transition zone.However,drilling operations in this area are susceptible to wall collapse and instability,creating significant risks.This study investigates the mineral composition and microstructure of reservoir rocks through drilling core observation,electron microscopy,CT scanning,and X-ray diffraction analysis.The findings reveal that the shale gas reservoir is predominantly composed of quartz and clay minerals,with a clay mineral content of 45.7%.Notably,montmorillonite is absent,while kaolinite represents 35%,and the illite/montmorillonite mixed layer accounts for 26%of the clay minerals.The rock samples exhibit nano-scale pore development,micro-crack formation with widths in the micron range,and interconnected narrow cracks.Analysis of alterations in interlayer spacing,surface tension,linear expansion rate,and crack expansion after rock-fluid interaction unveils that shale in the coastal transition zone solely undergoes surface hydration,offering insights into the mechanisms of rock-fluid interaction in shale gas reservoirs.Consequently,a high-performance water-based drilling fluid system specifically designed for the coastal transition zone shale gas reservoir is formulated,encompassing the selection of water-based drilling fluid inhibitors,plugging agents,and lubricants.The system is subsequently subject to comprehensive laboratory evaluation,which substantiates its exceptional performance in terms of conventional properties,inhibitory effects,sealing capabilities,and lubrication.It demonstrates a temperature tolerance of up to 100℃,experiences a fluid loss of merely 6 mL under high-temperature and high-pressure conditions,exhibits a shale swelling rate of 1.03%,possesses an overall drilling fluid lubrication coefficient of less than 0.15,reduces API filtration loss by 40%compared to the base slurry after 30 min,and effectively seals micro-cracks in the reservoir formations.Additionally,the system de

关 键 词：海陆过渡相 页岩 水基钻井液 井壁稳定 相互作用 

分 类 号：TE254[石油与天然气工程—油气井工程]