断块油气藏大落差阶梯水平井轨道优化

为了降低东濮凹陷断块油气藏大落差阶梯水平井管柱下入摩阻,开展了大跨距阶梯水平井轨道优化研究。考虑地层实际造斜能力,优化了造斜段的靶前位移和造斜率;建立了带封隔器(或扶正器)的完井管柱下入摩阻模型,优化了阶梯过渡段的井眼曲率和位移差。分析表明,造斜段靶前位移控制在300~400 m,造斜率先低后高,适当降低阶梯过渡段造斜率和位移差,有利于降低钻进和管柱下入摩阻。设计成果在东濮凹陷4口阶梯水平井中应用,阶梯着陆中靶率100%,储层钻遇率最大95.3%,水平段最长达到1 214 m,断块落差控制范围7.14~40.3 m。应用结果表明,采用分段评估的方法优化阶梯水平井轨道参数具有针对性和全面性,为同类型阶梯水平井的设计提供了借鉴。

Well-path optimization technology for stepped horizontal wells with large drop in the fault block reservoirs

In order to reduce the friction when running string in stepped horizontal wells in the fault block reservoir with large drop in the Dongpu depression, studies on optimization of well-path of stepped horizontal well with large span were carried out. Given the actual angle building rate of the formations, the pre-target displacement and build-up rate of the building up section were optimized. A model for analyzing the running friction of completion string with packer (or centralizer) and stress was built, and the wellbore curvature and displacement difference of the stepped transition interval was optimized. Analysis shows that, when the pre-target displacement at building up section is controlled at 300~400 m, the building rate is low first, then becomes high. Properly reducing the building rate and displacement difference of the stepped transition interval help reduce drilling friction and string running friction. The design result was used in four stepped horizontal wells in Dongpu Depression, the targeting rate of stepped landing was 100%, the maximum reservoir encountering ratio was 95.3%, the maximum horizontal section was 1 214 m, and the drop difference of faulted block was controlled at 7.14~40.3 m. The result of application indicates that the use of staged assessment method to optimize the parameters of stepped horizontal well track is pertinent and comprehensive and provides reference for the design of similar stepped horizontal wells.