Workover method based on low leakage temporary plugging process

Abstract

The invention discloses a workover method based on the low leakage temporary plugging process. The workover method is carried out according to the following steps that step one, temporary plugging kill fluid is prepared, the temporary plugging kill fluid is formed by dispersing temporary plugging polymer particles uniformly in curing brine, and the curing brine is prepared by dissolving or uniformly dispersing a curing agent, a curing initiator, a colloid-protect reagent and a brine regulator in fresh water or brine or mud; step two, a solid-free completion hydraulic well is pumped into an oil and gas well to detect leakage; step three, the temporary plugging killing fluid is pumped into the oil and gas well to follow up detection of the leakage; and step four, after the well is basically free of leakage, workover operation is carried out. The workover method based on the low leakage temporary plugging process has the advantages that a high water absorption temporary plugging polymerin the temporary plugging kill fluid forms a colloidal temporary plugging layer on a hole or a well wall through the physical dehydration and a chemical reaction, the leakage is effectively blocked,and the stability is good; and moreover, the temporary plugging polymer is easy to be acidified and degraded, and has no residue after degradation, subsequent production is not affected, and degradation products are environmentally friendly.

Description

technical field [0001] The invention belongs to the technical field of oil and gas well reconstruction, and in particular relates to a workover method based on a low-leakage temporary plugging process. Background technique [0002] Some oil and gas wells in most oil and gas fields have been exploited for a long time, and the formation pressure has dropped significantly. At present, most of the wells are lower than the hydrostatic column pressure. According to the previous operation in some areas, if the conventional brine workover fluid or well killing fluid system is used, a large amount of leakage will occur, and the fluid in the well is difficult to get rid of. The loss of a large amount of killing fluid will greatly change the water saturation around the wellbore, and the relative permeability of the gas phase will decrease, resulting in a significant decline in the production of the gas well after workover; at the same time, the killing and resumption period is longer, ...

AI Technical Summary

Problems solved by technology

According to the previous operation conditions in some areas, if the conventional brine workover fluid or well killing fluid system is used, a large amount of leakage will occur, and the fluid in the well is difficult to get rid of.

The loss of a large amount of killing fluid will greatly change the water saturation around the wellbore, and the relative permeability of the gas phase will decrease, resulting in a significant decline in the production of the gas well after workover; at the same time, the killing and resumption period is longer, which will affect the workover benefits

[0003] In some low-pressure, high-yield and high-sulfur wells, the tubing is perforated in many places, severely corroded or even broken. If high-density brine is used to workover the hydraulic well, it will cause leakage in the low-pressure layer. At the same time, the high-pressure layer will cause well overflow and kick, and the well will be killed repeatedly. It is easy to cause complex situations in the well, which increases the difficulty and unsafe factors of the operation

Moreover, the traditional temporary plugging agent is not tight when blocking, and there are phenomena such as air leakage and poor sealing effect, which cause the pressure in the sealed channel to fail to achieve the expected effect, and the output will be reduced during later collection.

At the same time, repeated leakage and well killing will increase the damage to the water phase trap in the atmosphere, resulting in a significant decline in gas well productivity after workover, greatly extending the operation cycle, and causing great economic losses.

The safety and environmental protection risks of gas wells with high hydrogen sulfide content are extremely high. At present, well killing technology, well killing fluid system technology, and on-site construction operations are in a bottleneck state, and the best purpose of workover operations cannot be achieved, which greatly reduces oilfield development benefits and safety risks. live in real time

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