Foam drilling fluid and preparation method thereof

Abstract

A foam drilling fluid is prepared from, in percentage by mass, 2%-4% of a first foaming agent, 1%-2% of a second foaming agent, 1%-3% of inorganic fibers and the balance of water, wherein dosage of the first foaming agent is the double of that of the second foaming agent. Under the normal-temperature and normal-pressure conditions, the inorganic fibers are dispersed in deionized water for prehydration treatment for 8-12 h, then the first foaming agent and the second foaming agent are added and evenly stirred at 60-80 DEG C, the mixture is foamed at the rotating speed of 5,000-8,000 rpm for 3-5 min, and the foam drilling fluid is prepared. The foam drilling fluid has good foaming capacity, high high-temperature-resistant and anti-pollution capacity, good dynamic yield point, good yield point and plastic viscosity ratio, good suspension property, higher inhibitive ability and proper water loss, can maintain the higher rate of penetration and water and rock carrying capacity in the drilling process and effectively solves the complex problems of wellbore instability, tool sticking, reservoir pollution and the like.

Description

technical field

[0001] The invention relates to a high-temperature-resistant and anti-pollution foam drilling fluid and a preparation method thereof, belonging to the technical field of petroleum drilling fluids. Background technique

[0002] Drilling fluid is one of the necessary materials used to balance formation pressure and ensure safe and smooth drilling during drilling. For deep oil and gas reservoirs with high shale content and high formation water salinity, it is best to use oil-based drilling fluids. However, oil-based drilling fluids cause serious environmental pollution, are easy to catch fire, and cost high. Conventional water-based drilling fluid density is difficult to control at 1.0g / cm 3 Below, the inhibition is poor, and when encountering high-salt deep well formations, the performance is prone to change, resulting in instability of the borehole wall and damage to the reservoir. Foam drilling fluid has low density, strong inhibition, good plugging ability...

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