川西蓬莱镇组大斜度井井壁稳定性及临界生产压差确定  

Wellbore stability and critical production pressure difference in high-angle deviated wells of Penglaizhen Formation,western Sichuan Basin

作　　者：龙章亮[1] 丁洁 曾贤薇[3] 王毅[1] LONG Zhangliang;DING Jie;ZENG Xianwei;WANG Yi(Petroleum Engineering Technology Institute,Sinopec Southwest Oil&Gas Company,Deyang,Sichuan 618000,China;Sichuan Jingchuandazheng Oilfield Technology Service Co.Ltd.,Chengdu,Sichuan 610000,China;Team 141,Coal Mine Exploration of Sichuan Province,Deyang,Sichuan 618000,China)

机构地区：[1]中国石化西南油气分公司石油工程技术研究院,四川德阳618000 [2]四川京川大正油田技术服务有限责任公司,四川成都610000 [3]四川省煤田地质局141地质队,四川德阳618000

出　　处：《天然气技术与经济》2022年第1期34-40,共7页Natural Gas Technology and Economy

基　　金：中国石化西南油气分公司科研项目“川西中浅层钻采工程标准化建设”(编号:GP0281)。

摘　　要：大斜度井和水平井是四川盆地西部上侏罗统蓬莱镇组主要高产井型。但由于川西地区碎屑岩地层砂泥岩互层频繁,大斜度井和水平井在钻井过程中普遍存在井壁失稳现象。特别是在大斜度井段,井壁失稳造成的掉块、遇阻、卡钻等复杂问题使得划眼及通井频繁,严重影响了钻井时效。为了给调整钻井液密度和控制生产压差等措施提供数据依据,保障钻井及生产安全,利用ANSYS有限元模拟了井眼内部应力分布,分析了井壁失稳的原因。研究结果表明:①35 MPa的等效应力为井壁失稳临界值,即随着深度的增加,钻井液的密度如果不变,当井壁受到的等效应力超过35 MPa时,就会导致井壁失稳;②当大斜度井轨迹平行于最大水平主应力方向时,井壁应力随井斜角增大而变小,当大斜度井轨迹平行于最小水平主应力方向时,井壁应力随井斜角增大而增大;③当大斜度井轨迹在平行最小水平主应力方向时,在相同井斜角条件下,井壁稳定性随生产压差增大逐渐变差。结论认为:在最大井斜角小于等于60°时,生产压差控制在9 MPa以内,井壁能够维持较好的稳定性;在最大井斜角大于60°时,生产压差控制在8 MPa之内,井壁能够维持较好的稳定性。High-angle deviated and horizontal wells are the main ones with high yield from Penglaizhen Formation,western Sichuan Basin.In this area,however,clastic rock is often interbedded with sandy mudstone,bringing about quite a lot of wellbore instability in drilling these wells.Especially in some high-angle deviated hole section,the fallout,blocking,sticking,and other complexities caused by wellbore instability may lead to frequent reaming and drifting,further affecting drilling efficiency seriously.In order to provide data base for adjusting drilling-fluid density,controlling production pressure difference,and making some measures to ensure safety,the stress distribution in borehole was simulated by means of ANSYS finite element.And then the instability law was analyzed.Results show that(1)the equivalent stress of 35 MPa is one critical value of wellbore instability.That is to say if the drilling-fluid density is constant,the wellbore will get unstable when the equivalent stress exceeds 35 MPa with depth increase;(2)when the trajectory in high-angle deviated wells is parallel to the maximum horizontal principal stress,the wellbore stress decreases with the increase of hole deviation angle.When the trajectory is parallel to the minimum horizontal principal stress,the wellbore stress increases with angle increase;and(3)when the trajectory in high-angle deviated wells is parallel to the minimum horizontal principal stress and the deviation angle is the same,the wellbore stability gets worse with the increase of production pressure difference.In conclusion,when the maximum hole deviation angle is less than or equal to 60°,wellbore stability can be maintained very well under the production pressure difference within 9 MPa.When the maximum angle is larger than 60°,the stability can be kept under the production pressure difference within 8 MPa.

关 键 词：四川盆地西部 上侏罗统蓬莱镇组 大斜度井 井壁稳定性 有限元模拟 临界生产压差 

分 类 号：TE21[石油与天然气工程—油气井工程]