页岩气双二维水平井极限延伸能力研究

页岩气藏的开发多采用水平井,水平段的延伸能力直接影响到页岩气藏的综合开发效益。双二维水平井具有施工难度小、邻井碰撞风险低、作业费用低等优点。根据长宁页岩气的钻井实际情况,分析了钻机承载能力、钻柱安全系数、地层承压能力及额定泵压等因素对水平井延伸能力的影响,推导了相应计算模型。以长宁已钻页岩气井为基础,计算了不同影响因素随水平段长度的变化。研究表明,双二维水平井的延伸能力主要受地层承压能力和额定泵压影响,钻井施工中应选择合理的钻井液密度和排量,降低水平段岩屑床高度,采取适当的堵漏措施,选择高额定泵压的钻井泵。

The study of limit extension ability of shale gas double 2D horizontal well

The shale gas reservoirs are mostly exploited by horizontal well. The extension ability of horizontal section directly affects comprehensive development benefit of shale gas reservoirs. Double 2D horizontal well has advantages such as less construction difficulty, lower risk of adjacent Wells, and lower operating costs. This paper analyzed different factors including bearing capacity of rig, safety coefficient of drill pipe, loading capacity of formation, rated pump pressure which affected extension ability of horizontal well. It put forward corresponding calculation models and calculated the variation of different factors as the horizontal section changed. The result demonstrated that the extension ability of double 2D horizontal well was mainly influenced by loading capacity of formation and rated pump pressure. In drilling construction, we should choose reasonable drilling fluid density and displacement, reduce the cuttings bed height, take appropriate plugging measures, and choose drilling pump with high rated pump pressure.