四川盆地泸州区块深层页岩气水平井钻井关键技术

Key Technologies for Deep Shale Gas Horizontal Well Drilling in Luzhou Block of Sichuan Basin

四川盆地泸州区块深层页岩气水平井钻井周期长、机械钻速低、钻具振动大,特殊岩性地层可钻性差、水平段井眼易失稳、地层温度高,且摩阻扭矩大、卡钻风险高。为保证作业安全,降低钻井成本,开展了水平井井身结构优化、水平段井眼轨道优化及轨迹控制等技术研究,推荐了激进钻井方式的最优参数,优选了特殊岩性地层减振提速和高效破岩技术;结合地面降温设备先导试验,优选了钻井液体系,并优化了钻井液性能参数,最终形成了泸州区块深层页岩气水平井安全高效钻井关键技术。该技术在泸州区块4口井中进行了试验,试验井平均井深5601 m,水平段长1884 m,钻井周期平均缩短14.5%,未发生井下故障。研究结果表明,该技术满足泸州区块安全高效钻井和推广应用要求。

Drilling deep shale gas horizontal wells in Luzhou Block of Sichuan Basin is challenging due to long drilling cycles,low rate of penetration(ROP),high drilling tool vibration,poor drillability of special lithological formations,horizontal wellbore instability,high formation temperature,and high friction torque and sticking risk etc.To solve these problems and to ensure operation safety and save the cost,technological research was carried out on the casing program design optimization of horizontal wells,and wellbore trajectory control and optimization of horizontal sections.As a result,the optimal parameters of the radical drilling method were recommended,and shock absorption,speed-up,and high efficiency rock breaking technologies for special lithological formations were selected.In addition,drilling fluid systems and performance parameters were recommended based on pilot tests of ground cooling equipment.Thus,key drilling technologies with high operation safety and efficiency were formed for the deep shale gas horizontal wells in Luzhou Block.The key technologies were tested in four wells in Luzhou Block,the results show that the drilling cycle was reduced by 14.5%on average and no downhole failures were reported with an average well depth of 5601 m and a horizontal section length of 1884 m.The research result show that the technologies can meet the requirement of safe and efficient drilling as well as having a wide application scope in Luzhou Block.