超深尾管防气窜固井技术研究

Research on cementing technology of ultra-deep liner gas channeling prevention

超深井尾管固井质量合格率偏低,井眼中存在的"大肚子"造成顶替效率偏低,环空桥堵、水泥浆从液态向固态转变引起的失重、套管与水泥体积收缩产生裂缝是引起窜槽的主要原因。通过提高套管居中度、优化钻井液性能、紊流顶替技术可以提高顶替效率,尾管顶部封隔器可以有效阻隔油气上窜,采用预应力固井工艺可以有效提高固井质量。利用该技术在蓬探区块共开展8口井现场试验,固井质量得到进一步提升,井筒密封完整性满足增产作业需求。

The qualified rate of liner cementing in ultra-deep Wells is on the low side,and the“Big belly”in wellbore results in low displacement efficiency,the main reasons of channeling are bridge plugging in annulus,weight loss caused by cement slurry changing from liquid to solid state,and cracking caused by shrinkage of casing and cement volume.The displacement efficiency can be improved by improving casing centricity,optimizing drillingfluid performance and turbulence displacement technology,and the Packer on the top of liner can effectively prevent oil and gas from channeling upward,the pre-stressed cementing technology can effectively improve the cementing quality.Field tests were carried out in 8 wells in Pengtan exploration block with this technology,and the cementing quality was further improved.