新疆硫磺沟煤田火烧区地热双水平井施工技术

Construction technology of dual horizontal wells for geothermal energy in the coalfield fire area of Liuhuanggou， Xinjiang

摘要:

本研究以新疆煤田火灾治理为背景，借鉴国外Eavor-Loop等闭式地热系统（CLGS）工程经验，旨在通过提取地下热能使煤田火烧区降温，以恢复火烧区煤炭资源开采，并实现地下热能利用的双重目标。采用闭式双水平井取热方案，设计了“稳斜+造斜+水平+造斜+稳斜”的五段制井眼轨道双水平井轨迹。针对煤田火烧区高温破碎地层特性，创新采用“小口径先导孔+大口径回拖扩孔”工艺完成施工，提出了适用于新疆硫磺沟煤田火烧区高温岩层的高效、低成本钻探和换热取热技术方案。针对施工中遇到的井下高温（>170 ℃）、地层不稳定和全井段大井斜等挑战，采取多种钻完井工艺方法，优化钻井液体系和设备，应用耐高温测量仪器及井下动力钻具，解决了钻遇煤田火区时地层松散破碎、失返漏失、异常高温等问题。为未来煤田火区钻完井施工形成可推广的技术范式。

Abstract:

This study is set against the background of coal fire control in Xinjiang. Drawing on international engineering experience with closed-loop geothermal systems （CLGS） such as Eavor-Loop， it aims to achieve dual objectives： extracting underground thermal energy to cool coal fire zones， thereby facilitating the recovery of coal resources in burned-out areas， and utilizing the geothermal energy obtained. A closed dual horizontal well heat extraction scheme was adopted， featuring a five-section well trajectory design- "build-up+tangent+horizontal+build-up+tangent". In response to the high-temperature and fractured formation characteristics of the coal fire area， an innovative "small-diameter pilot hole+large-diameter back-reaming" process was employed during implementation. This approach proposes an efficient and low-cost drilling and heat extraction technical solution suitable for high-temperature rock mass underground thermal energy reservoirs in the Liuhuanggou coalfield fire area. In order to solve the problems of high temperature （>170 ℃）， unstable strata and large inclination in the whole well， various drilling and completion techniques are adopted， the drilling fluid system and equipment are optimized， and the high temperature measuring instruments and downhole power tools are applied. As a result， issues such as loose and fractured formations， lost circulation， and abnormal high temperatures when drilling through the coal fire zone were successfully resolved. This work establishes a replicable technical paradigm for future drilling and completion operations in coal fire areas.