威荣深层页岩气垂深达3 800 m,地层坍塌压力系数高达1.95以上,区域超长水平井逐年增加,超长水平井成为后期气田稳产的重要开发手段。以旋转导向钻井方式研究为前提,通过水力裸眼评价模型和钻柱应力计算方法对地质参数、轨迹剖面、钻柱力学、水力参数和地面装备进行影响因素综合分析,不同钻机条件下和不同工况下超长水平段的延伸极限不同。剖面类型优选利于井间防碰和管柱安全下入,三维轨迹剖面钻柱力学所受应力强度是二维轨迹剖面的2倍,钻井液密度和黏度都将影响超长水平段的延伸。评价结果表明,在不考虑钻机能力的条件下,理论裸眼水平段极限为5 840 m,而70钻机因钻深能力限制最大水平段延伸为3 500 m,机泵排量越大,钻井液密度越低,延伸能力越长。

The vertical depth of Weirong deep shale gas reaches 3 800 m, and the formation collapse pressure coefficient is above 1.95. The ultra-long horizontal wells in the region are increasing year by year, and the ultra-long horizontal wells have become an important development means for stable production in the later stage of the gas field. Based on the research of rotary steerable drilling method, the hydraulic open-hole evaluation model and Landmark software are used to comprehensively analyze the influencing factors of geological parameters, trajectory profile, drill string mechanics, hydraulic parameters and surface equipment. The extension limits of the ultra-long horizontal section were different under different rig conditions and working conditions. The optimized profile type is beneficial to prevent collision between wells and safe running of pipe string. The stress intensity of the drill string in 3D trajectory profile is twice that of 2D trajectory profile, and both the density and viscosity of drilling fluid will affect the extension of ultra-long horizontal section. The evaluation results show that the theoretical limit of open hole horizontal section is 5 840 m without considering the drilling capacity, while the maximum horizontal section extension of 70 drilling rig is 3 500 m due to the drilling depth limit. The larger the pump displacement, the lower the drilling fluid density, and the longer the elongation capacity.