Three-layer separate injection string and three-layer separate injection method for oil well

Abstract

The invention discloses a three-layer separate injection string and a three-layer separate injection method for an oil well. The three-layer separate injection string comprises an outer pipe combination and an inner pipe combination, wherein the outer pipe combination comprises a large oil pipe, a first expanding packer, a division water distributor, a small oil pipe, a second expanding packer, a constant pressure switch and a ball seat which are fixedly connected sequentially from top to bottom; the inner pipe combination comprises the small oil pipe and a division insertion pipe, the division insertion pipe can be correspondingly abutted against a sliding sleeve in the division water distributor, and a gap is reserved between a non-insertion section of the division insertion pipe and a barrel of the division water distributor; the string is tripped in the designated location of a sleeve, and a steel ball is put on the ball seat; and setting pressure of the first expanding packer and setting pressure of the second expanding packer are smaller than shearing pressure of a shear pin of the constant pressure switch. The three-layer separate injection string is simple in structure and convenient to operate, not only can realize three-layer separate water injection and well washing, but also improves the water injection effect and the flexibility of water injection and well washing deployment greatly.

Description

technical field [0001] The invention relates to a water injection pipe string, in particular to a three-layer separate injection pipe string and a three-layer separate injection method for an oil well which realizes three-layer layered water injection and greatly improves the water injection effect. Background technique [0002] Oilfield water injection development has the effect of replenishing formation energy and improving oil well recovery, and has become the main means of post-production of most oilfields. At present, domestic three-layer water injection mainly adopts ground regulation, concentric water distribution pipe string and eccentric water distribution pipe string. However, the concentric water distribution pipe string has the problem of the success rate of casting and fishing nozzles, and has been gradually eliminated; while the eccentric water distribution pipe string must be tested for the pressure of the oil layer at the bottom of the well and the water dist...

AI Technical Summary

Problems solved by technology

However, the concentric water distribution pipe string has the problem of the success rate of casting and fishing nozzles, and has been gradually eliminated; while the eccentric water distribution pipe string must be tested for the pressure of the oil layer at the bottom of the well and the water distributor before use, and a special plug and fishing nozzle must be equipped. tools, so the process of eccentric water distributor is complex and difficult to operate, so it is basically not used in water injection wells below the fourth floor

At present, there are many kinds of split injection strings in China that can realize three-layer split injection, but all of them are eccentric water distribution strings, which have complex structures and difficulties in throwing and fishing; some of them can realize three-layer split injection, but the structure is complex , and the use of multiple packers is likely to cause the failure of the pipe string during the construction process, and the sealing performance needs to be further verified

Images