Design and application of injection-washing pipe string in self-lifting washable well

A new type of injection-washing pipe string in self-lifting washable well was developed to slove the problem of well washing failure in layered sand control water injection pipe column. A hydraulic lifting device was installed in lower part of the tube in borehole, and hydraulic cylinder be leveled up driving by the hydraulic lifting device from ground in the process of well washing. An isolation seal located in the bottom of water injection string was used to separate packer and sealing cylinder in order to establish the washing well channel. After the well washing, the lower part of water injection column goes down because of water injection pipe string weight and hydraulic pressure supplied from ground, and the isolation seal enter into the isolation packer and sealing cylinder again to realize the interlayer separation. Field application results show that the use of this pipe string effectively solve the problem of well washing and scale prevention in injection wells of offshore reservoirs.