涪陵页岩气井新工具的应用与经济评价

Application and the Economic Evaluation of New Tools in Fuling Shale Gas Wells

涪陵地区页岩层蕴含着丰富的天然气资源,具有较大的开采前景。区块主要目的层为上奥陶统五峰组-下志留统龙马溪组下部页岩气层。上部泥页岩地层井壁稳定性差,地层承压能力低,溶洞发育、易坍塌、易漏失;海相沉积地层流体分布复杂,部分地层岩性变化大,可钻性差,机械钻速较低;采用丛式布井,水平井井眼轨迹复杂,靶前位移大,大井眼定向扭方位困难、托压严重。现场试验使用了旋转导向、扭力冲击器、旋冲马达、水力振荡器等新技术、新工具,大幅度提高机械钻速,缩短钻井周期,取得一定的经济效益。阐述了几种新技术和新工具的工作原理、现场应用情况,并对其经济效果进行了评价。

Shale beds of Fuling area contain abundant natural gas resources with good exploration prospect. The main target strata in this block is shale gas bed in upper Ordovician Wufeng formation-the lower part of lower Silurian Longmaxi forma- tion. In the upper shale formation, borehole wall stability is poor and formation pressure bearing capacity is low with karst development as well as collapse and leakage ; fluid distribution of marine sedimentary formation is complex, litbology chan- ges in some formations with poor drillability and low ROP. Cluster wells were adopted, but the horizontal wellbore trajectory is complex with large displacement, it was difficult for large directional borehole rectified azimuth and back pressure was serious. New technologies and new tools were used in field experiment, such as rotary steering drilling technology, tortion impacter, rotary impaction motor and hydraulic oscillator, the penetration rate was greatly improved and the drilling cycle was shortened. In this paper, these new technologies and new tools are elaborated in the working principles and field application and the economic effects are evaluated.