预弯曲钻具组合在软硬交错地层的应用

油气井的防斜打快问题是石油钻井面临的一大难题。川西地区中浅部地层岩性软硬交错程度显著,导致钻井易井斜的问题,前期主要通过国外垂钻系统解决该问题,钻井成本高。预弯曲钻具组合是一种低成本防斜打直技术,但是在软硬交错地层的应用尚缺乏科学的适用性评价方法。提出了一种考虑地层软硬交错特征及地层倾角影响的易斜地层预弯曲钻具选择方法,实现了软硬交错地层的造斜力计算,进而选择能提供相当防斜力的预弯曲钻具组合进行防斜应用。分析结果表明,在川西地区,地层倾角小于25°、软硬交错指数小于3时,预弯曲钻具组合可以提供足够的防斜力。应用该技术进行了现场应用,预弯曲钻具组合取得了较好的防斜提速效果,证明这种评价方法力学原理明确,模型准确可靠,应用简单,可以为软硬交错易斜地层低成本防斜打快技术提供可靠参考。

Study on the Application of Pre-bending Drilling Technology in Soft and Hard Staggered Formations

The anti-deviation and fast drilling technology of oil and gas well is a difficult problem for oil engineering. The shallow strata in western Sichuan have a remarkable characteristic of soft and hard lithology interlacing, which leads to the problem of well deviation. This problem was solved mainly by the foreign vertical drilling system, and the drilling cost is high. Pre-bending BHA is a low-cost anti-deviation technology, but there is still a lack of scientific applying evaluation method in the soft and hard staggered formations. In this paper, a method of choosing pre-bending drilling tools which considering the influence of soft and hard lithology interlacing and strata dip angle is proposed systematically. The calculation of inclination force in soft-hard cross strata is realized, and then the pre-bending drilling tools which can provide sufficient anti-inclination force is selected for application. The analysis results show that the pre-bending drilling assembly can provide sufficient anti-deviation force when the dip angle of formation is less than 25 and the cross index of hard and soft is less than 3 in western Sichuan. The technology has been applied in the field, and the pre-bending drilling assembly has achieved good anti-inclination and speed-up effect. It proves that the evaluation method is accurate and simple to use, which can provide reliable reference for low-cost anti-inclination technology in soft-hard staggered formation.