Temporary plugging well killing fluid for fractured reservoirs, and application and preparation method thereof

Abstract

The invention provides a temporary plugging well killing fluid for fractured reservoirs and application and a preparation method thereof. The temporary plugging well killing fluid comprises a base solution and degradable shape memory polymer particles, the base solution is a composite gel, the degradable shape memory polymer particles are composed of polymers with different deformation recovery amounts, and the degradable shape memory polymer particles are injected into a reservoir stratum through a base solution carrying pump, enter a fractured reservoir stratum, expand due to temperature response, and recover the shape. Temporary plugging and well killing can be achieved for a fractured gas well, low-damage well repair of low-pressure-coefficient and ultralow-pressure-coefficient and low-yield gas wells can be met, the fluidity is good at the ground temperature, and pumping injection is easy. After entering the fractured reservoir, the pressure bearing performance is rapidly improved, the subsequent clear water workover fluid loss is greatly reduced, the operation safety is ensured, and the reservoir damage is reduced. Shape memory polymer particles with different degradation periods can be selected according to the operation requirements, and can be completely degraded after the operation is completed, and the flow-back and the production recovery are fast.

Description

technical field [0001] The invention belongs to the technical field of oil and gas well workover and well killing fluids, and in particular relates to a temporary plugging well killing fluid for fractured reservoirs and its application and preparation method. Background technique [0002] In the later stage of gas field production and development, most wells need to take workover and other downhole operation measures to ensure continuous production. However, as the production volume increases, the formation pressure continues to decay. The loss of killing fluid was serious, it was difficult to establish circulation in the wellbore, and the well could not be killed normally. Especially in carbonate rock formations, natural fractures are developed, and most of the artificial fractures that are stimulated by fracturing are complex, and after long-term production, the fractures are connected, often causing vicious leakage and serious damage to the reservoir, which makes the gas ...

AI Technical Summary

Problems solved by technology

[0008] In the preparation of the above-mentioned various temporary plugging and killing fluids, ordinary gel and its composite plugging agent have obvious viscosity characteristics and poor temperature resistance, and the pressure bearing capacity cannot meet the downhole working environment of ultra-low pressure coefficient formations

However, the plugging agent added with solid phase materials has poor flowback performance, and the recovery effect is poor for low-pressure and low-production fractured gas wells

Self-degradable temporary plugging gel, its degradable fiber only plays a role in strengthening the colloid, but does not have an adaptive plugging effect on the production layer. At the same time, the colloid cross-linked by the amphoteric metal ion cross-linking agent has general temperature resistance Not high, poor adaptability to the high temperature of the current carbonate formation

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