Temporary plugging workover fluid for low-pressure carbonate reservoir gas well and preparation and application method of temporary plugging workover fluid

Abstract

The invention discloses a temporary plugging workover fluid for a low-pressure carbonate reservoir gas well and preparation and an application method of the temporary plugging workover fluid. The temporary plugging workover fluid is composed of two slugs, wherein one is a low-solid phase water-locking type temporary plugging fluid slug, and mainly plays roles of forming a temporary plugging layerat a blasthole, bearing pressure of an upper fluid column and balancing formation pressure difference; the other slug is a water-based anti-swelling inhibitor slug, and mainly plays a role of furtherreducing damage caused by a small amount of workover fluid entering the reservoir due to micro-leakage. The temporary plugging workover fluid provided by the invention has the characteristics of lessleakage, small reservoir damage, strong pressure bearing capacity and water-locking capacity, good universality, non-toxicity, harmlessness, convenient construction, easy flowback, high safety, environmental protection and the like, is mainly used for temporarily plugging and killing the well in the carbonate reservoir during workover, is particularly suitable for workover of the low-pressure carbonate reservoir gas well having tubular columns with packers, and can reduce the damage of the workover fluid to the formation.

Description

technical field [0001] The invention relates to the technical field of gas well workover, in particular to a temporary plugging and workover fluid for gas wells in low-pressure carbonate rock reservoirs and its preparation and application methods. Background technique [0002] Well workover is a work to restore normal production of oil and gas wells or increase production capacity to eliminate faults and improve wellbore conditions. The working fluid used in the workover operation is called the workover fluid. The workover fluid can ensure the safety of construction operations and prevent the workover fluid from leaking into the formation, thereby protecting the reservoir. [0003] At present, in the workover process of low-pressure gas fields at home and abroad, clay-free water-based workover fluids are generally used. There are roughly three types of workover fluids: clay-free clean brine workover fluids, low-solids-free Clay phase workover fluid, other types such as foam...

AI Technical Summary

Problems solved by technology

The disadvantage is that the workover operation time is long, and the contact time between the formation and the fluid is long, especially for low-porosity and low-permeability gas reservoirs, the degree of water lock damage will still be serious

[0005] Low solids and clay-free workover fluids can quickly form plugs in holes or fractures and control the loss of workover fluids. The disadvantage is that the solid phase particle invasion during the workover process will easily cause reservoir pore throat blockage, making it difficult to flow back , especially for low-permeability gas layers, it is difficult to remove plugging, and it is easy to cause damage to the reservoir

It can be seen that for the current gas wells in low-pressure carbonate reservoirs containing single or multiple packers, it is currently impossible to achieve temporary plugging and workover. Temporary plugging and workover fluid suitable for this type of tubing string with a packer in low-pressure carbonate reservoir gas wells and its application method

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