保护煤储层的煤层气井固井技术

国内的煤层气井主要采用注水泥射孔方式完井,研究固井设计和施工的一些关键问题对于避免潜在的生产作业和开采效益风险具有重要意义。简要回顾了国内煤层气井固井施工和研究状况,分析了煤层气井固井的质量要求和保护储层需求,结合室内和现场试验提出了适用于煤层气井固井的水泥浆性能和施工设计方法。研究认为煤层气井固井中最重要的封隔要求是对煤储层顶板的封隔,首要的作业安全问题是防止漏失。综合考虑固井作业和保护储层需要认为:适宜的水泥浆密度范围为1.20~1.60 g/cm3,并应采用黏稠水泥浆在0.5~0.8 m/s的低返速下固井施工。现场应用的固井质量合格率达到100%,证明该研究结论适用于煤层气井固井。

Cementing technology used for protecting coal reservoir

It is very important to perform a systemic research on cementing operational parameters and its influence upon the coal-bed gas exploitation,because the cased-hole completion is the main well completion method for coal-bed gas well in China.Based on the brief review of cementing operation cases and the current research of coal-bed gas well,this paper analyzed the requirements of cementing quality and protection the coal reservoir.It tabled a proposal of the slurry and operation design method combining with the experiments and operations.The isolation of coal reservoir roof is the most crucial requirement in coal-bed well cementing and the most important challenge of operational safety was preventing the lost circulation.Considered the requirement of cementing job and protection the coal reservoir,it was proposed that the desired cementing slurry density boundary should be(1.20)-(1.60)g/cm~3,at the same time,the thick cement slurry should be under the low return rate,(0.5)-0.8 m/s,in the cementing operation.The cement job quality qualification rate has reached 100% in the field application,which proves that this conclusion has be of certain applicability and be of directive meaning for coal-bed gas well cementation operation and design in future.