Water-based drilling fluid for low-temperature formation drilling

Abstract

The invention relates to a water-based drilling fluid for low-temperature formation drilling. The technical solution of the invention is that the water-based drilling fluid is prepared with the following components in parts by weight: 100 parts of water, 0 to 4 parts of mixing soil, 0.1 to 5 parts of flow pattern regulator, 1 to 8 parts of shale inhibitor, 0.05 to 0.5 parts of encapsulating and inhibiting agent, 3 to 10 parts of filtrate reducer, 10 to 40 parts of hydrate inhibitor, 1 to 2 parts of lubricant and 0 to 100 parts of barite. The water-based drilling fluid has the following advantages: (1) the drilling fluid disclosed by the invention has good fluidity under the low temperature of negative 5DEG C, the plastic viscosity is less than or equal to 40mPa.s, and the yield point is less than or equal to 25Pa; (2) the drilling fluid disclosed by the invention has good borehole wall stability and filtration and wall-building properties, the swelling rate of clay can be deceased by about 70 to 90 percent, and the highest shale recovery ratio reaches 88.2 percent (21.1 percent for clean water); the API filtration loss is less than or equal to 5mL; (3) the drilling fluid disclosed by the invention has good hydrate inhibition property, and no hydrate is produced after the drilling fluid is mixed for 16 hours under the conditions of negative 5DEG C and 15MPa; (4) the lubricating coefficient of the drilling fluid disclosed by the invention is less than 0.1, which can meet the requirement of drilling operation.

Description

technical field [0001] The invention relates to a drilling fluid for oil and natural gas development, in particular to a water-based drilling fluid for drilling in low-temperature formations, which is applied to deep-water oceans and low-temperature formations in permafrost zones. Background technique [0002] Marine deep-water oil, gas and gas hydrate resources are rich and have great potential; tundra zones also contain rich gas hydrate resources. Compared with land or shallow sea drilling, drilling in deep ocean and permafrost ultra-low temperature formations faces many special technical problems, and the drilling fluid must have the following characteristics: (1) Good low temperature rheology. With the increase of water depth, the seawater temperature is getting lower and lower, and the lowest seabed temperature in the Gulf of Mexico, the South my country Sea and West African waters is 2~4°C. The low temperature causes the viscosity and shear force of the drilling fluid...

AI Technical Summary

Problems solved by technology

However, the drilling fluid only evaluates and optimizes the rheological properties, without considering comprehensive properties such as wellbore stability, hydrate inhibition, and fluid loss performance.

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