采动区综采工作面地面“L”型钻井瓦斯抽采技术

Gas extraction technology with L-shaped ground well drilling in mining area

为防治高瓦斯碎软低渗煤层综采工作面瓦斯超限难题,提出了地面"L"井瓦斯抽采技术,基于杨柳煤矿10煤1071工作面工程地质及瓦斯抽采条件,对"L"井井位布置技术、井身结构设计、施工关键技术、瓦斯抽采效果等进行了综合研究。结果表明:地面"L"井水平段在纵向上须处于覆岩裂隙带中部偏下,在横向上须与"O"形圈有效沟通;"L"井宜设计为三开井身结构,其中三开段采用筛管完井,为有效抽采段;"L"井水平段施工,采用MWD、交替滑动钻进与复合钻进、优选钻具组合等方法控制井眼轨迹,井眼全角变化率大,上仰段井斜达93°~94°;采用套管分步连环精确开窗侧钻及打捞成套工艺确保了"L"井多分支孔的顺畅施工;泄水孔堵塞是导致"L"井抽采效果不理想的主因。该成果可为煤矿瓦斯灾害防治、煤与瓦斯共采实践等提供理论依据及技术借鉴。

To prevent the occurrence of gas over-limit problem for the purpose of efficient mining,in the fully mechanized coal mining working face in soft coal seam with highly gas and low permeability, a comprehensive study was conducted on the “L” well layout, the design of the well structure, the key technology of construction and the effect of gas extraction, based on the engineering geology and gas extraction conditions of 10# coal seam at the 1071 working surface of Yangliu coal mine. The results show that the horizontal section of the L-shaped well should be located in the lower part of the overlying fracture zone in the longitudinal direction and effectively connected with the “O” ring in the trans verse direction. The L-shaped well is designed as three-spud structure and the third spud section is the effective extraction part which is constructed with screen completion. MWD, alternating slide drilling and compound drilling, optimizing assembly of drilling tools and other methods for borehole trajectory control were used in constructing horizontal section of the L-shaped well, whose total angular changing rate of the borehole is large and upward section is up to 93°-94°. The casing step-by-step, precise opening, side drilling, and the salvage complete process were used to ensure the successful construction of the multi-branch holes. The blockage of drain hole is the main reason that the pumping effect of “L” well is not satisfactory. The results can provide theoretical basis and technical reference for coal mine gas disaster prevention and control, coal and gas co-mining practices.