In November 2014, Sinopec Zhongyuan Petroleum Engineering Corp. made a new national record of the deepest extra-large-diameter gas well cementing in its operation in West No.1 gas well in Zhujidong coal mine of Huainan Mining Industry (Group) Co., Ltd., providing a good example of coal-bed gas cementing technology in China.
630mm coal-bed pipeline went down 930 meters in this gas well with designed cement volume of 280 tons. In the cementing operation, the pipeline tended to be distorted or broken due to large diameter, thin pipe wall and consequent pressure difference inside and outside. Moreover, the large annular capacity would lead to high risks of cement channeling. Before the operation, Sinopec Zhongyuan Petroleum Engineering Corp. had many discussions with the project owner to get more detailed geological information on the block, improve cementing design and adjust the performance of cement before working out the best solution. For the on-site operation, Sinopec Zhongyuan Petroleum Engineering Corp. rigorously followed the operation process and succeeded in the first operation. Cement paste flowed back to the surface and everything was normal under the well without any leaking of underworkings. After 72 hours of cement solidification, the exploration showed that the level of cement plug met the project owner’s requirements and passed the pressure test.