复合盐层井壁失稳机理及防塌钻井液技术  

Wellbore instability mechanism and wellbore stabilizing drilling fluid technique for drilling compound salt formation

作　　者：赵欣[1] 邱正松[1] 张永君 周国伟[1] 黄维安[1] 

机构地区：[1]中国石油大学(华东)石油工程学院,山东青岛266580

出　　处：《中南大学学报（自然科学版）》2016年第11期3832-3838,共7页Journal of Central South University:Science and Technology

基　　金：国家科技重大专项(2011ZX05030-005-07);国家自然科学基金资助项目(51374233)~~

摘　　要：针对两伊(伊朗、伊拉克)边境A&M油田复合盐层钻井过程中存在的稳定井壁技术难题,采用X线衍射、扫描电镜、滚动分散及膨胀实验测试复合盐层的矿物组构和理化性能,分析井壁失稳机理。制定"强化封固井壁作用—抑制复合盐层溶解及水化—化学位活度平衡—合理密度支撑井壁"多元协同防塌钻井液对策,优选出适合复合盐层钻井的封堵剂和无机、有机复合盐等关键处理剂,构建密度为2.3 g/cm3的多元复合盐水钻井液。研究结果表明:该钻井液黏度低,切力适中,有效地控制当量循环密度;高温高压(120℃,3.5 MPa)下滤失量为7.0 m L,滤失造壁性优良;不同矿物组成的复合盐层岩样在钻井液中的回收率均在90%左右,有效抑制复合盐层的溶解、分散;对宽度为200μm的裂缝的封堵承压能力达到5.5 MPa以上,具有优良的随钻封堵性能,可满足复合盐层钻井技术需求。In order to solve the wellbore instability problem when drilling compound salts formation in A＆M Oilfield in the border of Iran and Iraq, the fabric and physical-chemical properties of compound salts were tested by X-ray diffraction, scanning electron microscope, hot rolling dispersion test and linear swelling test, and wellbore instability mechanism was analyzed. A multivariate cooperation principle for stabilizing the wellbore in compound salts drilling was designed, which includes enhancing the performance of sealing and consolidating borehole, enhancing the inhibition on dissolution and hydration of compound salts, balancing chemical potential and activity, and maintaining reasonable density of drilling fluid to support the wellbore. According to the principle, the sealing additives and salts mixture consisting of organic and inorganic salts were optimized, and the high density （2.3 g/cm3） multi-component salts drilling fluid for drilling compound salts was formed. The results show that the rheological property of the drilling fluid is good. As a result, the equivalent circulating density can be well controlled. The low fluid loss volume （7.0 mL） at 120 ℃ and 3.5 MPa indicate the excellent filtration property of the drilling fluid. The recovery rates of different kinds of compound salts rocks are up to approximately 90% in the drilling fluid, indicating the excellent inhibition property of the drilling fluid on dissolution and dispersion of compound salts. The drilling fluid can seal fractures of 200μm in width, and the bearing capacity is up to at least 5.5 MPa, which indicates that the drilling fluid has excellent sealing property while drilling, and can meet the requirement of compound salts drilling.

关 键 词：复合盐层 井壁失稳 溶解 多元复合盐 钻井液 裂缝 

分 类 号：TE254[石油与天然气工程—油气井工程]