A downhole steam injection pipe string for heavy oil thermal recovery well

Abstract

The invention discloses a downhole steam injection pipe string in a heavy oil thermal recovery well, which can protect the casing in the steam injection well, improve the steam dryness at the bottom of the well, and improve the thermal efficiency and steam injection effect of steam injection. The steam injection pipe string includes heat insulation pipe and suspension packer, heat insulation pipe, backwash valve and sealing telescopic pipe are sequentially connected to form the steam injection inner pipe string; suspension packer is sequentially connected with sealing sleeve and switch assembly to form The steam injection outer string; the suspension packer of the steam injection outer string is seated and suspended on the inner wall of the casing, and the sealed telescopic tube of the steam injection inner string is inserted into the switch assembly of the steam injection outer string and can be Sliding in the sealing sleeve. The invention can realize one-time decentralization and multiple use, the quality of steam injection is obviously improved, the oil-gas ratio is improved, and the oil-increasing effect is obvious. The pipe string of the present invention has simple structure, reliable operation, improved steam sweep volume and multi-round steam injection efficiency, fully saves energy, effectively protects the casing, and eliminates the leakage of the casing head at the wellhead of the existing steam injection pipe string. disadvantages.

Description

technical field [0001] The invention belongs to the downhole steam injection pipe string of the petroleum industry, in particular to a downhole steam injection pipe string of a heavy oil thermal recovery well, which can protect the casing in the steam injection well, improve the dryness of the steam at the bottom of the well, improve the thermal efficiency and steam injection efficiency of steam injection. Effect, save energy, improve oil-gas ratio. Background technique [0002] Due to the high viscosity of heavy oil reservoirs, it is not easy to flow. How to pump it from the formation to the wellbore, and then lift it from the wellbore to the surface is a relatively difficult problem. Injecting steam into the oil layer to reduce its viscosity is the most commonly used and most effective method at present. However, the oil layer is one to two thousand meters deep underground. During the process of injecting steam into the oil layer with a pipe string from the surface, if th...

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Problems solved by technology

But at the same time, if the steam injection pressure difference is 15Mpa, the upward force generated by the pressure difference acting on the thermal packer also reaches 300KN. Since the thermal packer has no fixed anchoring device, the relative up and down of the thermal packer and the casing Sliding release, its seal is damaged, causing steam to leak into the casing above the thermal packer, and conduct to other formations, resulting in a large loss of heat energy, damage to the casing, and easily cause leakage of the casing head at the wellhead , leading to poor steam injection effect in the oil layer, failing to achieve the purpose of viscosity reduction production

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