克深Y井盐层固井难点分析与技术对策

克深Y井四开钻遇多段盐层、漏失层和高压水层。盐层蠕变较强，下套管中途遇阻的风险高；高压水层和漏失层共存，固井安全密度窗口窄，仅为0.03 g/cm3，漏失和溢流的风险高；低漏失压力且套管偏心条件下，顶替差，难以封隔高压水层。该盐层固井难题的应对对于该井的钻探至关重要。通过分析地质工程条件，制定了盐层扩眼+模拟管柱通井技术措施；以漏失及溢流压力评估为基础，对固井工艺进行了论证并确立了正注反挤+及时憋压的固井方案；结合软件模拟技术，优化了扶正器方案和隔离液流变性能，并采用大排量顶替和多倍置换等系列措施提高顶替效率。制定的技术措施均在现场应用，结果显示，套管顺利到位，下放过程无阻卡；正注固井未漏失未溢流，反挤固井排量较大塞面可控；喇叭口负压验窜合格，实现了封隔水层的核心目标，为本区块应对盐层固井难题提供了参考。 

Difficulties in Cementing Salt Formation in Well Keshen-Y: Analyses and Technical Measures

The fourth interval of the well Keshen-Y penetrated several salt zones, mud loss zones and high pressure formation water zones. High creeping tendency of salt may cause resistance to casing running. A narrow safe drilling window of only 0.03 g/cm3 in a hole section where high pressure formation water and mud loss zone coexist may cause mud loss and overflow. In well cementing operation, low leak-off pressure and eccentricity of casing string result in poor displacement of mud and hence difficulties in cementing the high pressure water zones. Several measures have been developed to address these problems. First, based on the analyses of the geological and engineering conditions, it was decided to ream the salt sections and to perform wiper trip with a simulation string. The well cementing techniques were reviewed based on the evaluation of leak-off pressure and overflow pressure, and a "normal injection reverse squeezing plus timely pressurizing" cementing program was established. Using software simulation, the placement of centralizer and the rheology of spacer were optimized, and high flow rate and multiple displacement were used to increase the displacing efficiency. Field application of these technical measures showed that the casing string were run smoothly to the designed depth. No lost circulation and overflow have ever occurred during normal injection cementing. High flow rate was obtained and the top of cement was controllable during reverse squeezing cementing. Channeling test at the bell nipple at negative pressure was certified, indicating that the water zones were successfully cemented.