精细控压钻井中气体溢流识别与排气降压技术

Gas Overflow Identification and Exhaust Pressure Reduction Technology in Fine Pressure Control Drilling Wells

四川盆地勘探开发逐步向高压、高产、高含硫、超深井等深部复杂地层推进,精细控压工艺因作业流程差异导致传统录井设备无法开展随钻监测,制约了作业现场对井下异常情况及时发现。由于同一裸眼段存在多个不同的压力系统,钻遇油气显示层压井后钻井液密度高,无法满足下部地层钻进需要,面临溢漏同存和无安全密度窗口的复杂局面,文章建立了一套适用于精细控压期间气体溢流快速识别方法,并利用排气降压技术通过降密度和释放地层流体方式,重建安全密度窗口,有效解决深井、超深井同一裸眼段多个压力系统漏溢同存、高密度钻进无法满足下部钻进需要等钻井难题。通过在川中蓬莱气区现场应用表明,排气降压技术既降低复杂风险又节约钻井周期,具有广泛应用前景。

Exploration and development in the Sichuan Basin are gradually advancing towards deep and complex formations such as high pressure,high yield,high sulfur,and ultra deep wells.The use of precise pressure control technology has resulted in traditional logging equipment not being able to effectively carry out monitoring while drilling due to differences in operating procedures,which has restricted the timely detection of abnormally high-pressure gas reservoirs on the job site.Moreover,due to the existence of different pressure systems in the same open hole section,the drilling fluid density is high after drilling in abnormally high-pressure gas reservoirs,unable to meet the drilling needs of the lower formation,facing the complex situation of simultaneous leakage and no safety density window,this article establishes a rapid identification method for abnormally highpressure gas layers during fine pressure control.By using exhaust pressure reduction technology to reduce density and release formation fluid,the safety density window can be reconstructed,and the low success rate of high-pressure and low-permeability primary well killing can also be effectively solved drilling difficulties such as difficulty in dealing with trapped pressure caused by well killing and plugging,as well as long processing time for transitional gas layers.Through on-site application in the Penglai gas field in central Sichuan,it has been shown that exhaust pressure reduction technology not only reduces well control risks but also saves drilling cycles,and has broad application prospects.It provides reference and support for solving drilling problems such as the lack of safety density windows and the formation of trap pressure,transitional gas layers,and high-pressure and low-permeability formations due to well killing and plugging in China.