Self-expansion patching method of oil-well casing

Abstract

The invention provides a self-expansion patching method of an oil-well casing. The self-expansion patching method comprises the following steps: an operating cable and a tool set are connected, and abase tube patched with an organic composite with a shape memory function is fixed between an electromagnetic expansion disc and a rigid expansion head; a wellhead is fixed, and the operating cable anda ground cable operating vehicle are connected; the operating cable drives the tool set and the patched base tube to be lowered into a well; casing damage parts are positioned, and the base tube patched with the organic composite is set; the ground is powered on; the base tube patched with the organic composite is heated to the temperature higher than the shape restoration temperature of the basetube, and the base tube is subjected to first-time interference expansion to be patched onto casing damage sections; the cable is upwards lifted, and the tool set overall upwards travels, wherein therigid expansion head, an elastic expansion head and a plug conduct second-time expansion on the base tube patched with the organic composite; and the cable and the down-hole tool set are pulled out from the interior of the well. According to the self-expansion patching method, a construction process is simple, operation is convenient, and the patched base tube is good in corrosion resisting property, safe and reliable.

Description

technical field [0001] The invention relates to an oil well casing self-expanding subsidy method, which belongs to the technical field of casing damaged wells in oil and gas fields. Background technique [0002] Casing damaged wells refer to oil, gas and water wells with damaged casings. Generally, according to the nature of casing damage, it can be divided into casing deformed wells, casing faulted wells and casing broken leakage wells. The casing damage of oil, gas and water wells is an important factor affecting the stable production of oil fields. [0003] The hazards to oilfield production after oil well casing breakout mainly include the following points: 1. After casing breakout, the formation water in the upper part of the oil layer backflows, which intensifies the blockage of the oil layer near the wellbore, resulting in loss of production capacity. 2. After the casing is broken, the wellbore is often corroded and scaled intensified, which increases the difficulty...

AI Technical Summary

Problems solved by technology

[0003] The hazards to oilfield production after oil well casing breakout mainly include the following points: 1. After casing breakout, the formation water in the upper part of the oil layer backflows, which intensifies the blockage of the oil layer near the wellbore, resulting in loss of production capacity

2. After the casing is broken, the wellbore is often corroded and scaled, which increases the difficulty of the operation

3. After the casing is broken, the development well pattern of water injection and oil production will be out of balance, and the effect of water flooding will not be effectively exerted, resulting in a decline in the development level and the remaining oil cannot be used

4. After the cover is broken, the pressure system is damaged, and it is difficult to collect and analyze dynamic testing data

[0004] After the water injection well is broken, it may cause the high-pressure injection water to fail to enter the target oil layer effectively, and even lead to hidden dangers such as safety

[0005] After the natural gas production well casing is broken, the main hazards are as follows: 1. After the casing is broken, the formation water in the upper part of the gas layer will flow back, resulting in water flooding of the gas layer or an increase in the water content of the produced gas, resulting in loss of production capacity

2. After the casing is broken, the wellbore is often corroded and scaled, which increases the difficulty of the operation

3. After the casing is broken, high-pressure natural gas escapes from the well into the outer formation, which brings safety and environmental protection risks

(4) During the construction process, the hydraulic cold extrusion expansion device of the expansion tube is relatively complicated, and the expansion cone is prone to be stuck in the expansion tube, which can neither be pulled out nor continued to expand and advance, which increases the difficulty of operation processing

(5) After expansion, a series of pipe string operations such as bottom drilling and plugging are required, with many process steps and long operation period

(6) The carbon steel expansion pipe is prone to secondary corrosion damage in the environment of carbon dioxide, corrosive bacteria or hydrogen sulfide in the well, resulting in treatment failure

The use of corrosion-resistant alloy pipes (titanium-based, nickel-based, etc.) is more expensive, the protection and requirements for the pipe body during the expansion process are higher, and the construction process is more complicated

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