拱形水平井的设计方法研究

STUDY ON ARCHED HORIZONTAL WELL DESIGN

用一口水平井开发两个甚至多个连续薄油气藏、层叠状油气藏、断块油气藏等,相当于2口甚至2口以上水平井的开发效果,可以节约钻井投资、提高单井产能及采收率。合理地确定水平井段的井斜角和方位角是实现水平井优化设计的基础,根据地层倾角和走向,给出了2种水平井段井斜角的计算方法。拱形水平井段是以单圆弧作为过渡井段,用一口水平井开发2个具有不同井斜角的油气层。分析了拱形水平井的设计特点,指出过渡井段的造斜率是拱形水平井设计的一个关键参数,设计和施工时还需要考虑携带岩屑和钻压传递问题,以有利于井眼清洁和降低钻柱摩阻。在此基础上,探讨了二维和三维拱形水平井的轨道设计方法,并给出了设计示例。

To develop two or more continuous thin reservoirs, stacked reservoirs or fault block reservoirs by only one horizontal well can achieve the similar development results of two or more horizontal wells besides saving drilling costs, improving single-well productivity and increasing recovery rate. To get an optimal horizontal well design, the key is to determine the proper inclination and azimuth of the well. Two methods based on formation dips and trends are given in the article for inclination design of horizontal section. An arched horizontal well is to use an arc section as the transition section to achieve the purpose of producing from two reservoir zones which have different inclinations. The characteristics of the arched horizontal well design are analyzed, finding the buildup rate of the transition arch section is a key parameter, in addition cuttings transport, WOB transmission, etc. being taken into consideration to facilitate well cleaning and reduce drill string drag. And finally the design methods for 2D and 3D arched horizontal wells are further discussed, and examples are given to demonstrate.