摘要
Wh-1X井φ215.9 mm井眼井底6828 m(裸眼长1178 m)处溢流压井压开的压裂缝、侧钻井眼井底7114.65 m(裸眼长1464.65 m)放空处的洞穴裂缝均导致钻井液失返井漏,需井底堵漏。研究认为,砂泥岩互层的长裸眼井底桥接堵漏,要消减钻具在裸眼段对井底实施桥堵压开上部薄弱地层造成的卡钻风险,就要建立全裸眼井筒承压理念。首先钻具在技术套管内对井底以上的薄弱地层进行桥堵提高承压,然后钻具再进裸眼对井底进行堵漏,并配合使用旋转控制头技术措施消减卡钻风险。研究认为,桥堵材料的级配及使用浓度存在严重的缺陷是导致原井眼多次桥堵失败的根本原因,裂缝及洞穴裂缝桥接堵漏要取得成功,桥堵浆堵漏材料的级配和浓度必须满足头等尺寸材料的大尺寸和高浓度、种类多样的次等尺寸材料梯度匹配及合理浓度、高的桥堵浆总浓度这3个条件,缺一不可。畅通的井眼通道对桥堵浆稠塞顺利到达漏层位置很重要。采用以上技术和原理,侧钻井眼通过2次钻具在套管内桥堵堵住了5650~5668 m、5830~5842 m、6279~6288 m三个漏层,一次钻具在裸眼内桥堵堵住了6644~6649 m及7114.54~7114.65 m井底放空段2个漏层,共计堵住了5个漏层,恢复了钻井作业并成功建井。
The well Wh-1X has experienced whole mud losses into induced fractures formed when killing the well at 6828 m(φ215.9 mm,open hole length was 1178 m)and mud losses into caves at 7114.65 m in a sidetracked section(open hole length was 1464.65 m).The mud losses at the bottoms of the hole had to be stopped.It was believed that,to minimize the risk of pipe sticking caused by fracturing the upper weak formations when controlling mud losses into interbedded sandstone and mudstone at the bottom of the well with bridging method,the whole open hole section should be strengthened to bear pressures that may fracture the open hole.First,the drill string was run inside the technical casing to improve the pressure-bearing capacity of the weak formations above the hole bottom with bridging.Second,run the drill string into the open hole and control mud losses taking place at the bottom of the hole.By rotating the control head during mud loss control,the risk of pipe sticking was minimized.It was further believed that,failure in previous mud loss control was because of the serious defects in sizing and concentration of the bridging materials used.To succeed in controlling mud losses into fractures and caves with bridging method,three prerequisites should be satisfied:Large size and high concentration of firstclass size bridging agents,gradient matching and reasonable concentration of various sub-size bridging agents,high total concentration of the bridging agents.Unobstructed wellbore is important for the bridging slurry to reach the depth at which mud losses are taking place.Using the technology and principle aforementioned,three mud loss zones,5650-5668 m,5830-5842 m and 6279-6288 m in the sidetracked hole,were bridged successfully by running the drill string inside the casing twice,and two cave loss zones,at 6644-6649 m and 7114.54-7114.65 m respectively,were bridged successfully by running the drill string once into the open hole.The five loss zones were all at the bottom of the well when mud losses were taking place.Success in mud loss control helped drill the well successfully.
作者
周志世
张震
张欢庆
王辉
孙俊
罗威
杨川
张宁
ZHOU Zhishi;ZHANG Zhen;ZHANG Huanqing;WANG Hui;SUN Jun;LUO Wei;YANG Chuan;ZHANG Ning(Tarim Oilfield Oil and gas Engineering Research Institute,Korla,Xinjiang 841000;Beijing KMS Oilfield Chemical Technology Co.,Ltd,Beijing 100089;Xinjiang Branch of Chuanqing Drilling company,Korla,Xinjiang 841000)
出处
《钻井液与完井液》
CAS
北大核心
2020年第4期456-464,共9页
Drilling Fluid & Completion Fluid
关键词
长裸眼
断层
裂缝
放空
井漏
失返
桥接堵漏
桥堵
凝胶
Fault
Fracture
Drilling into cave
Lost circulation
Lost return
Control mud loss with bridging
Bridging
Gel
