A well completion string and cementing method

Abstract

The invention discloses a well completion tube string and a cementing method. The tube string comprises a guide shoe, a sieve tube, an isolating valve, a bushing A, a packer, a bushing B, a double-stage cementing device, a bushing C, a drilling linear hanger and a feeding drill from bottom to top in sequence. The method comprises the following steps: keeping the interior and the exterior of the tube communicated during descending through the isolating valve; isolating the interior from the exterior of the tube after the descending is finished. A blind plate is replaced through the isolating valve in the well completion tube string; during descending, circulation and automatic grouting can be performed; and meanwhile, the pressure surge problem caused by a dead space is avoided. After the descending of the tube string is finished, a ball can be thrown to build pressure, a hanger is hung, the packer is set, and the double-stage cementing device is started to perform cementing operation on the top of the sieve tube.

Description

technical field [0001] The invention relates to the field of petroleum cementing, and more particularly, to a well completion pipe string and a method for cementing. Background technique [0002] At present, the construction process pipe string used in general screen completion is (bottom-up): floating shoe + tail pipe string (screen pipe string) + blind plate + hydraulic packer + double-stage cement injector + tail pipe String + liner hanger + feeding drill. The lower end of the completion pipe string is a blind plate, and a relatively closed pressure "dead space" is formed in the pipe. During the running process, if the pipe string encounters resistance, it cannot circulate; The packer will be opened in advance, resulting in the failure of the packer to be set and the hanger to be set and hung, and it is difficult to continue the follow-up work. [0003] Chinese patent 02237904.5 introduces the suspension liner double-stage cementing string. Both the hanger and the doubl...

AI Technical Summary

Problems solved by technology

The lower end of the completion pipe string is a blind plate, and a relatively airtight pressure "dead space" is formed in the pipe. During the running process, if the pipe string encounters resistance and cannot circulate; The packer will open in advance, resulting in the inability of the packer to be set, the hanger to be suspended, and subsequent work to be difficult to continue

[0003] Chinese patent 02237904.5 introduces a two-stage cementing string with a suspended liner. Both the hanger and the two-stage cementing tool are mechanical, which are only suitable for vertical well sections and not for horizontal wells or highly deviated wells.

[0004] Chinese patent 201738822 introduces the gravel packing completion string in the upper part of the cementing lower part of the horizontal well, including the completion string and pickling packing string, and the completion pipe connected to the lower end of the casing is the lead wire + screen + blind plate +packer+grading hoop+casing pup joint, etc. Due to the existence of the blind plate, the pipe string of this process needs to be grouted in time during the running process, and the running speed must be strictly controlled during the running process, and it is easy to lift and release Pressure surges lead to premature expansion of packers and early opening of grading hoops, etc.

Due to the presence of blind plates in this process, the pipe string needs to be grouted in time during the run-in process, and the lowering speed must be strictly controlled during the lowering process. When the string is lifted and lowered, it is prone to pressure surges, which will cause the packer to swell and seal in advance, and the grading hoop open in advance etc.

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