Method for preventing casing wear in oil field

Abstract

The present invention discloses a method for preventing bushing damage; the method is mainly used for selecting and controlling reasonable water injection pressure; the water injection pressure is a water injection pressure which can obtain maximum liquid producing amount without threatening the safe stress of the bushing. And, the reasonable water injection pressure is lower than the bursting pressure of discharging hole top board under single layer exploitation condition; the reasonable water injection pressure is controlled adjacent to the original ground pressure under multiple layer combine exploitation condition; the cement job quality can be considered when determining the reasonable water injection pressure, the water injection pressure is original ground pressure at the area with good cement job quality and is lower the original ground pressure at the area with middle cement job quality. The technology scheme of the invention can effectively prevent the generation of bushing damage and has stronger practical instruct meaning and operability.

Description

Technical field: [0001] The invention belongs to the field of petroleum and natural gas exploitation, and relates to a method for preventing casing damage. Background technique: [0002] In the exploitation of oil and gas, it is necessary to bury a large number of casings in the formation, and these casings will be damaged during use, thereby affecting the extraction of oil and gas. Macroscopically, the factors leading to casing damage can be divided into three categories: geological factors, engineering factors and other factors. It is a consensus at home and abroad to study the mechanism of casing damage from the perspective of rock mechanics and fluid mechanics, but in general, casing damage is not caused by a single factor in many cases, but the result of a combination of various factors. [0003] Regarding the problem of casing damage, many achievements and understandings have been achieved in the past ten years, which can be summarized as follows: [0004] ① In the c...

AI Technical Summary

Problems solved by technology

[0004] ① In the case of a large difference in formation pressure in adjacent blocks, based on the float-over theory, high pore pressure can relatively increase the shear force on the formation slope, resulting in rock mass displacement and casing damage

[0006] ③Based on the theory of structural stress, it is believed that the stress concentration near the structural axis and faults will cause disturbance stress changes during water injection and oil recovery, which will easily damage the casing

[0008] ⑤Other factors: engineering factors such as poor casing quality, improper perforation or fracturing technology, and unstable operation during downhole operation and maintenance, etc.

The cause of the casing damage has not been found fundamentally, so the preventive measures do not cure the symptoms, resulting in casing damage from time to time

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