勺形水平井在四川长宁页岩气r开发中的应用

摘要

随着四川长宁页岩气进入新的开发阶段,丛式水平井平台正下方储层无法动用的问题突显,目前沿用的常规水平井无法有效应对,严重制约了长宁页岩气的高效开发.勺形水平井是解决该问题的有效方法之一.通过研究勺形水平井的技术原理,基于长宁区块地质情况设计了页岩气勺形水平井,并结合长宁区块第1口勺形水平井——CN-S井的试验情况对勺形水平井的应用进行了分析.分析结果表明:勺形水平井通过产生反向位移将入靶点提前,可使水平段增加300 m左右,可使平台下方死气区面积缩小至30 m×800 m,储层动用面积增加95%;钻井摩阻低(实测下钻摩阻为10~15 kN,起钻摩阻为5~10 kN,油层套管下入摩阻为15~20 kN),套管下入顺利,具有技术可行性.实例表明,勺形水平井在长宁页岩气应用是可行的,能有效增加储层动用面积,节约钻井成本,对页岩气的经济高效开发具有重要意义.%With development of shale gas development in Changning,Sichuan entered new stages,problems related to under-development of reservoirs directly underneath the derrick for cluster horizontal wells become more out-standing. Incapability of conventional horizontal wells may present significant obstacles for high-efficiency develop-ment of shale gas in Channing. In fact,spoon-shaped horizontal wells are considered effective solution to remove such obstacles. By studying technical principles for spoon-shaped horizontal wells,spoon-shaped horizontal wells for shale gas development have been designed in accordance with specific geologic conditions in the Channing Area. In addition,performances of such wells have been analyzed in accordance with test data in the Well CN-S,the first spoon-shaped horizontal well drilled in the Channing Block. Analysis results show the spoon-shaped horizontal well may prolong the horizontal interval for approximately 300m by extend the target point through reversed displacement. In this way,the area with no gas development underneath the derrick can be reduced to 30 m×800 m to enhance the development area for approximately 95%;With low friction resistances in drilling (with measured friction resist-ance in drilling of 10-15 kN,bit tripping-out resistance of 5-10kN and production casing tripping-in resistance of 15-20 kN),casing pipes can be installed freely. Test results show the spoon-shaped horizontal wells can be de-ployed for shale gas development in the Channing Area to enhance development efficiencies of reservoirs and to cut drilling cost. In conclusion,application of spoon-shaped horizontal wells can effectively promote high-efficiency development of shale gas with satisfactory economic performances.