Degradable self-plugging-removal temporary plugging agent for reservoir drilling fluid, and preparation method thereof

Abstract

The invention relates to the technical field of oil and gas well development, and concretely relates to a degradable self-plugging-removal temporary plugging agent for water-based solid-free reservoir drilling fluid suitable for oil and gas well drilling, and a preparation method thereof The degradable self-plugging-removal temporary plugging agent for the reservoir drilling fluid is a blend of a biodegradable polymer temporary plugging material and acid-soluble temporary plugging particles. Practice proves that acidification degradation can be generated within a period of time after well completion, the temporary plugging rate of the temporary plugging agent is greater than or equal to 98%, the plugging removal rate is greater than or equal to 99%, and the reservoir core permeability recovery value is greater than or equal to 95%; meanwhile, the temporary plugging agent disclosed by the invention has a self-plugging-removal capability, self-plugging removal can be realized by hydrating and decomposing a self-generated acid solution through a biological degradable material during later reverse drainage, the processes of removing mud cakes through acid pickling and the like are not needed, secondary damage to a reservoir is avoided, and the temporary plugging agent is a simple, convenient, efficient and side-effect-free temporary plugging technology.

Description

technical field [0001] The invention relates to the technical field of oil and gas well development, in particular to a degradable self-plugging temporary plugging agent for water-based solid-free reservoir drilling fluid suitable for oil and gas well drilling and a preparation method. Background technique [0002] During the drilling process, when the oil and gas layers are opened, the first thing they come into contact with is the drilling and completion fluid. The solid phase particles in the liquid can easily invade into the natural pores near the well wall and cause reservoir pollution. With the flushing action, part of the immersed drilling fluid will be removed, but most of the drilling fluid will still remain in the pores, and the remaining drilling fluid will not only block the pores, but also pollute the reservoir, which will hinder the recovery of reservoir permeability , the production of the oil well will decrease. In recent years, many different plugging remov...

AI Technical Summary

Problems solved by technology

[0008] CN103834369A discloses a self-removing plugging fluid for drilling carbonate rock reservoirs. The drilling fluid includes 5-16 parts by mass of a composite self-removing temporary plugging agent, 2-6 parts by mass of a fluid loss reducer, 0.1 -0.8 parts by mass of viscosifier, 0.1-0.5 parts by mass of pH regulator, 0.1-0.5 parts by mass of waterproof locking agent, 0-7 parts by mass of potassium chloride and 0-230 parts by mass of weighting agent, with good fluid loss and wall building The recovery value of carbonate rock core permeability is > 87%, no need to use gel breaking fluid, but the self-plugging temporary plugging agent still needs to be deplugged by pickling

The problem is that hydrophobic modification may lead to uncontrollable fluid loss of drilling fluid

[0010] Aiming at the current problems of self-unplugging drilling fluids, a variety of polymers or bio-enzyme materials have been disclosed as plugging agents, but they still have certain defects in terms of plugging rate and permeability recovery value, and further research is needed. Research and development of new self-plugging materials

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