Down-hole steam injection string of thick-oil thermal production well

Abstract

The invention discloses a down-hole steam injection string of a thick-oil thermal production well. The down-hole steam injection string is capable of protecting a casing in a steam injected well, improving the dryness of steam at the bottom of the well, and improving the steam injection heat efficiency and the steam injection effect. The steam injection string comprises a heat insulation pipe and a wall-hook packer; the heat insulation pipe, a backwashing valve and a sealed telescopic pipe are orderly connected to form an internal steam injection string; the wall-hook packer is orderly connected with a sealing sleeve and a switch assembly to form an external steam injection string; the wall-hook packer of the external steam injection string is down and sealed and hung on the inner wall of the casing; the sealed telescopic pipe of the internal steam injection string is inserted in the switch assembly of the external steam injection string and is capable of sliding in the sealing sleeve. The down-hole steam injection string of the thick-oil thermal production well can be reused after being put down once; the steam injection quality is obviously improved, the oil-steam ratio is increased, and an obvious oil increasing effect is achieved. The down-hole steam injection string of the thick-oil thermal production well is simple in structure and reliable in working; besides, the swept volume of the steam and multi-turn steam injection efficiency are improved, the energy source is thoroughly saved, the casing is effectively protected, and the defect of leakage at the wellhead casing head of the existing steam injection string is eliminated.

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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