西江区块古近系地层井壁失稳机理分析及钻井液体系优化  

Analysis on wellbore instability mechanisms and drilling fluid system optimization for the Paleogene strata in Xijiang block

作　　者：狄明利[1] 赵远远[1] 由福昌 吴宇 侯珊珊 DI Mingli;ZHAO Yuanyuan;YOU Fuchang;WU Yu;HOU Shanshan(Shenzhen Operations Company,China Oilfield Services Limited,Shenzhen,Guangdong 518067,China;Jingzhou Jiahua Technology Company Limited,Jingzhou,Hubei 434000,China)

机构地区：[1]中海油田服务股份有限公司深圳作业公司,广东深圳518067 [2]荆州嘉华科技有限公司,湖北荆州434000

出　　处：《中国海上油气》2020年第1期134-141,共8页China Offshore Oil and Gas

基　　金：中海油田服务股份有限公司科研项目“西江区块古近系地层井壁失稳机理及钻井液对策研究(编号:YIIB17YF006)”部分研究成果

摘　　要：为解决西江区块古近系地层井壁失稳、电测遇阻等技术难题,通过分析古近系地层井下复杂情况、全岩及黏土矿物组成、微观结构、理化性能特征及钻井液特性,认为井壁失稳机理为微裂隙弱面发育和高含黏土矿物的水化作用。在此基础上,建立了钻井液关键性能与井壁稳定性的内在联系,即钻井液密度为1.30g/cm3时,满足井径扩大率≤15%且坍塌周期≥10d(工期)的岩石浸泡10d后的内聚力≥7.2MPa。通过添加抑制剂PF-UHIB、物理封堵剂PF-AquaSeal和化学封堵剂PF-SmartSeal等对钻井液性能进行了优化,实验评价表明优化后的钻井液体系岩屑回收率大于90%、线性膨胀率小于3%、内聚力8.9MPa。目前优化后的钻井液体系已在西江区块古近系地层取得成功应用,具有较好的推广应用价值。In order to solve technical problems such as wellbore instability and E-logging stuck in Paleogene strata of Xijiang block,by studying the complex conditions of Paleogene strata,the compositions of whole rock and clay minerals,the microstructure,the physical and chemical properties,the characteristics of drilling fluids,it is analyzed that the wellbore instability mechanisms are due to the weak planes development of micro-fractures and the hydration of high clay minerals.The internal relationship between key properties of drilling fluid and wellbore stability has been established,that is,when the drilling fluid density is 1.30 g/cm3,the rock cohesion after immersion for 10 days shall be≥7.2 MPa,so it can achieve the hole enlargement rate of≤15%and a collapse period of≥10 d(construction period).The properties of drilling fluid can be optimized by adding inhibitor PF-UHIB,physical plugging agent PF-AquaSeal,and chemical plugging agent PF-SmartSeal.The experimental evaluation results show that the optimized drilling fluid system has a cuttings recovery rate of greater than 90%,linear expansion rate of less than 3%and the cohesion of 8.9 MPa.The optimized drilling fluid system has been successfully applied in the Paleogene strata of Xijiang block,and it shows a good prospect for popularization and application.

关 键 词：西江区块 古近系地层 井壁稳定 钻井液 岩屑回收率 内聚力 线性膨胀率 

分 类 号：TE254.1[石油与天然气工程—油气井工程]