Water-based drilling fluid suitable for long-section horizontal well of shale gas and application of water-based drilling fluid

Abstract

The invention relates to a water-based drilling fluid suitable for a long-section horizontal well of a shale gas and an application of the water-based drilling fluid. The water-based drilling fluid is prepared from the following components in parts by weight: 100 parts of water, 0.5-5 parts of bentonite, 0.1-0.4 part of sodium carbonate, 0-8 parts of an inorganic salt, 1-5 parts of a filtrate reducer, 0.1-1 part of a viscosity enhancer and carrying agent, 0-1.5 parts of a wetting agent, 0.5-5 parts of a shale inhibitor, 1-5 parts of a lubricant, 1-6 parts of a micro-nano blocking agent, 0-3 parts of a viscosity reducer, 0-1 part of a pH modifier and 0-280 parts of a weighting material. According to the drilling fluid, the density can reach 2.3g / cm<3>, the high-temperature and high-pressure filter loss is smaller than 5ml and the rheological property, the filtration reducing property, the lubricity and the inhibitive ability are equivalent to those of an oil-based drilling fluid; the surface performance of the shale can be improved, the hydrophobicity can be strengthened and the compressive strength of the shale is retarded; the water-based drilling fluid has good antifouling property and high sealing capacity; shale micro cracks can be sealed; pressure transmission is retarded or blocked; and the well-bore stability of the shale is facilitated.

Description

technical field [0001] The invention relates to a water-based drilling fluid suitable for horizontal wells with long well sections of shale gas and an application thereof, belonging to the field of exploitation of shale oil and gas resources. Background technique [0002] In recent years, the development of shale gas has received widespread attention at home and abroad. Drilling fluid technology is one of the key technologies for shale gas horizontal well drilling. The horizontal section of shale oil and gas horizontal wells used for commercial development is generally 1000-2500m long, with well-developed shale micro-fractures and beddings. During the construction process, the drilling fluid has extremely high requirements on wellbore stability, lubricity and wellbore cleaning ability . Therefore, oil-based drilling fluid is the first choice in the drilling process of shale gas horizontal wells at home and abroad to deal with the problems of wellbore instability and high f...

AI Technical Summary

Problems solved by technology

In addition, shale gas in my country coexists in both marine and continental facies, and continental shale is deeply buried, low in maturity, and low in brittle mineral content, so wellbore collapse is prone to occur

At the same time, under the condition of high-density drilling fluid, the problem of high friction in long-section horizontal wells will become more prominent

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