Self-expanding subsidizing device for oil well casing and subsidizing method thereof

Abstract

The invention discloses a self-expanding patching device and method for an oil well casing. The method comprises the following steps: taking a memory alloy pipe of which the outer diameter is smaller than the inner diameter of the casing as a patching pipe substrate; fixing a rubber seal ring on the outer wall of the memory alloy pipe via a temperature-resistant adhesive, so as to obtain a patching pipe; lowering the patching pipe to the damaged position of the casing with an underground tool releasing device; heating the patching pipe with temperature in a well, so that the memory alloy pipe expands fast when temperature of the memory alloy pipe reaches a training temperature, and is tightly patched to the inner wall of the casing, that is, the casing pipe is repaired, wherein the training temperature depends on the damaged position of the casing. As the patching pipe deforms in one direction, the sealing and the blocking are reliable, the strength is high, and the internal pressure resistance and the external collapse resistance of the damaged casing can be improved obviously after the casing is repaired. Moreover, as the patching pipe has a self-expanding property at a set temperature, the casing can be repaired without taking measures such as hydraulic expansion or gunpowder explosion. Therefore, the operation is convenient, the construction is safe, the flaking off possibility is low, and the service life is long.

Description

technical field [0001] The invention belongs to the technical field of casing damaged well treatment in oil fields, and in particular relates to an oil well casing self-expanding subsidy device and a subsidy method thereof. Background technique [0002] With the prolongation of oilfield development time, casing damage of oil and water wells is becoming more and more serious. At present, the most commonly used casing subsidy method at home and abroad is the expansion pipe subsidy method. For example, "a hydraulic variable diameter casing expansion method and its equipment" (CN 1807830A). The method of cone cold extrusion and expansion causes plastic deformation of the steel pipe, subsidizes the inner wall of the damaged casing, and closely adheres to the damaged casing to form a double-layer casing, restore the integrity of the casing, and achieve the purpose of repairing the casing. The subsidy materials used mainly include seamless steel pipes and ERW longitudinal welded ...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are: (1) When the hydraulic expansion cone expands and moves, its force point must be fixed on the inner wall of the casing, and the anchor fluke will cause new damage to the casing

(2) The hydraulic cold extrusion expansion device is relatively complicated, and it is prone to jamming during construction. It cannot be pulled out, and it cannot continue to expand and move forward, causing underground accidents

(3) The process is complicated, the cost is high, the subsidy period is short, and the construction risk is high

The disadvantages of this method are (1) The energy generated by the explosion is difficult to control, if it is too small, the purpose of subsidy cannot be achieved, and if it is too large, the casing will be deformed or damaged

(2) Fires in oil wells are very dangerous. Once associated gas exists, major safety accidents such as oil well fires are likely to occur

Images