科钻一井侧钻作业设计与施工

The Sidetracking Design and Operation in Well CCSD-1

科钻一井主孔取心钻进至井深3 665 m时发生扩孔器折断事故,由于井内掉块严重,导致多次打捞失败。在进行扩孔钻进前起出活动套管时又有大量套管扶正器扶正钢板落入井内．扩孔钻进时又有3个扩孔钻头的导向体落井,加上井眼局部严重扩径,落鱼打捞或处理难度非常大,决定侧钻绕障。由于水泥塞强度与地层岩石强度差别大,开新井眼困难,经慎重设计、精心施工,采取了合理选择侧钻点、正确设计造斜率和选配马达弯角以及采用小直径开窗、大直径扩孔、小钻井参数钻进等技术措施使得侧钻绕障一次成功,为主孔后续正常钻进奠定了良好基础。

The diamond reamer with a diamond core bit was broken down into the bottom of well CCSD-1 （a well in Chinese Continental Scientific Drilling Project） while drilling to depth of 3 665 m. The fishing job failed due to the severe well wall sloughing. A lot of steel plates from casing stabilizers were loosened and fell into the bottomhole during moving casing string before hole reaming, and three guiding bodies of the reamer also dropped. All these, along with severe wellbore caving-in, make fishing job very difficult. As a result, a sidetracking operation is considered. The large difference between the strength of cement plug and formation rock causes difficulties in making a new hole. On the basis of careful de sign, the technical measures of selecting reasonable sidetracking point, designing proper building up rates, optimizing bent angle of mud motor, sidetracking by smaller bits, reaming via larger size bits, lower drilling parameters, etc. are taken and the sidetracking operation succeeded, which lays a good foundation for subsequential drilling operations.