Research and application of layered water injection pipe string anchored by bottom support

The water injection wells in Huabei Oilfield are characterized by great wellbore depth, high temperature, large deviation, etc. Historically, various types of packers were used for layered injection, but the pipestring in most injection wells had a short effective period. Some pipestrings were hard to be tripped out and even repaired. So such pipestrings could not satisfy layered injection into reservoirs. Analysis of downhole stress on conventional layered injection pipestring demonstrated the causes for their short service life and put forward the anchoring mode of bottom support of layered injection pipestrings, which solved the problem of up and down creepage of injection pipestring in deep wells. In addition, the present packers, when used for layered injection, have a large unsetting load and need to be serviced. The new type of stepwise unsetting packers developed lately can solve the problem of safe tripping out of downhole conventional packers and is of some promotion significance.