海域水合物储层安全钻井液温度窗口确定新方法  

Novel Method for Determining the Safe Mud Temperature Window in Marine Hydrate-bearing Sediments

作　　者：李庆超 刘钰文 吴静娟 LI Qingchao;LIU Yuwen;WU Jingjuan(School of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China;Shanxi Petroleum Company,China National Aviation Fuel Group Limited,Taiyuan 030032,China;School of Material Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China)

机构地区：[1]河南理工大学能源科学与工程学院,河南焦作454000 [2]中国航油集团山西石油有限公司,太原030032 [3]河南理工大学材料科学与工程学院,河南焦作454000

出　　处：《油气与新能源》2024年第5期44-56,共13页Petroleum and new energy

基　　金：国家自然科学基金联合基金重点支持项目“超深井安全高效井筒工作液构建及调控方法基础研究”(U1762212);河南省科技攻关项目“弱成岩水合物储层井眼坍塌机制及防塌调控技术”(242102320342);河南省高校基本科研业务费专项项目“弱成岩水合物储层井眼坍塌机制及防塌调控技术”(NSFRF240616)。

摘　　要：南海北部的含水合物沉积物通常胶结性较差、抗压强度极低,在钻井过程中极易发生井壁失稳等复杂井下事故。基于此,构建了用于探究水合物储层钻井过程井壁稳定性分析的多场耦合数学模型,探讨了钻井液温度对井眼稳定性的影响。在此基础上,提出了考虑井眼适度坍塌的安全钻井液温度窗口确定方法,得到了安全钻井液温度-密度设计推荐图版。研究发现:尽管通过数学模型得到的水合物分解范围与前人研究有差异,但两者极为相近,说明该数学模型可用于井眼稳定性的多场耦合模拟分析;具有较高温度的钻井液会刺激井周水合物的剧烈分解,从而使井眼稳定性状况恶化;当钻井液温度由14.79℃升高到24.79℃时,井眼扩大率会由4.2%提高到42.6%;钻井液密度、温度设计值推荐区域会随着井眼扩大率允许值的增大(即井眼稳定性要求的降低)而显著变大。研究成果不仅可为水合物储层钻井液设计提供技术支持,还为井眼稳定的维持提供新思路。The hydrate deposits in the Shenhu area in the north of South Sea typically exhibit poor cementation as well as lowest compressive strength and such geomechanical issues as borehole instability easily occur during the development operations.This paper builds up a multi-physics coupled mathematical model to perform numerical analysis of wellbore stability during drilling in hydrate reservoir,discusses the impact of drilling fluid temperature on wellbore stability,proposes a method for determining the safe mud temperature window considering moderate borehole collapse,and obtains a recommended design chart for the safe mud temperature and density.It finds that the dissociation ranges of gas hydrate obtained by the mathematical model in this study closely aligns with the results in previous investigation though they are a bit different indicating the mathematical model is suitable for simulating wellbore stability in hydrate-bearing sediments,drilling fluid with higher temperature stimulates the dissociation of gas hydrates around the wellbore,thereby deteriorating the stability of wellbore,the borehole enlargement rate increases from 4.2%to 42.6%as the mud temperature rises from 14.79℃to 24.79℃,and the recommended area for drilling fluid density and temperature design values significantly increase with the increase of the allowable borehole enlargement rate(the decrease in requirements for wellbore stability).The research results not only provide technical support for the design of drilling fluid for hydrate reservoirs,but also a new idea for maintaining wellbore stability.

关 键 词：水合物储层 井眼坍塌 钻井液温度 温度-密度图版 数值模拟 

分 类 号：TE254[石油与天然气工程—油气井工程]