During the infill drilling in the second and fourth fault blocks of Gangxi Aera 1 in Dagang Oilfield, lost circulation of-ten happens in the target layers. The faulted block oil reservoirs are located in Minghua and Guantao Formations with burial depth of 700-1500 m. Oil layers are closely distributed in the vertical direction and many small oil layers are always developed in the depletion mode without energy supplementation, so the reservoir pressure is low with pressure coefficient of 0.85. And consequently, the pressure bearing capacity of target beds cannot satisfy the requirements of originally designed second-section cementing, and the subsequently cementing quality is impacted seriously. To improve cementing quality, the casing program for well completion of drilling free two-stage cementing was designed after the reasons for lost circulation were analyzed. The combination technology of relay drilling free two-stage cementing device and external casing packer with backing pin was researched and developed. By virtue of relay drilling free two-stage cementing device, the technical issues are solved successfully, such as two-stage cementing, coordination with the external casing packer with backing pin and drilling free. The qualified cementing rate is over 90%.%大港油田港西油田一区二、四断块在加密钻井中,经常发生目的层井漏的问题.该断块油藏为明化镇组、馆陶组,埋深700~1500 m,纵向上油层分布密集,许多小块油层常年枯竭式开采,造成地层低压,压力系数0.85,目的层承压能力满足不了原设计的二开井固井的要求,给后续固井质量带来了严峻的问题.为提高固井质量,针对漏失的原因,进行了免钻双级注水泥完井井身结构设计,研究开发了"接力式"免钻双级注水泥器和带档销套管外封隔器的联作技术,"接力式"免钻双级注水泥器成功地解决了双级固井与带档销套管外封隔器的配合、免钻等工艺问题,现场应用固井质量合格率大于90%.
展开▼
