调整井钻井过程中地层压力控制技术的研究与应用

萨中开发区经过长时间的分层注采,地层孔隙压力分布发生了极大变化,出现了高压层、正常压力层及欠压层在单井纵向剖面上并存的情况,给加密调整井的钻井施工安全、钻井液密度设计及油层保护带来了极大的困难。根据该区块的储层特性和开发现状,对该区块内不同井网注水井降压规律进行研究,确定合理的注水井降压方案、钻井液密度以及注水井降压时间及降压范围;同时进行高渗低压层压力保持方法研究,通过控制注水井的井口压力来降低层间压差和钻井液密度,减少对油层的污染。此研究对于保护油层及提高钻井工程质量具有重要意义。

Research and application of geopressure controlling technology in drilling infilling wells

For the long-time separate layer injection and production in Sazhong oilfield, the pore pressure distribution has varied greatly and abnormal high-pressure formations, normal pressure formations and underpressured formations coexist in the longitudinal profile of a single well. It has brought difficulty in maintaining the drilling construction safety, controlling drilling fluid and reservoir protection when drill infilling wells. In this paper, based on reservoir characteristics and development practice of this oilfield, the decompression laws of the different flooding pattern is found out and proper decompression program of the injection wells, reasonable concentration of drilling fluid, right close time and the limited area are determined. Meanwhile, it has obtained the methods of pressure maintenance in high-permeability and low- pressure zone. Through controlling wellhead pressure of the injection wells, it can blow down the interlayer pressure difference, decrease the drilling fluid concentration and reduce the reservoir pollution. This research is important to the reservoir protection and improvement of the quality of drilling projects.