High-density oil-based drilling fluid and preparation method thereof

Abstract

The invention relates to the field of high-density oil-based drilling fluid, in particular to a high-density oil-based drilling fluid suitable for a high-pressure shale gas stratum and a preparation method thereof. The high-density oil-based drilling fluid is prepared from the following raw materials in parts by weight: 80-90 parts of base oil, 2-4 parts of a main emulsifier, 0.5-3 parts of an auxiliary emulsifier, 1-2 parts of organic bentonite, 2-3 parts of an alkalinity regulator, 3-5 parts of a filtrate reducer, 10-20 parts of a calcium chloride water solution with a mass fraction of 25-35%, and a weighting agent, wherein the main emulsifier is composed of higher fatty acid ester diethylene triamine, maleic polyamide and polyoxyethylene ether, and the auxiliary emulsifier is sodium dodecyl benzene sulfonate. The oil-based drilling system taking the diesel oil or white oil as the continuous phase has a good emulsifying effect, a high demulsification voltage, low water loss under a high pressure at a high temperature, a strong inhibition performance, and good fluidity under a high solid content.

Description

technical field [0001] The invention relates to the field of high-density oil-based drilling fluid, and more specifically relates to a high-density oil-based drilling fluid suitable for high-pressure shale gas formations and a preparation method thereof. Background technique [0002] In recent years, with the great development of deep well drilling technology, the continuous increase of drilling depth, and the increasing number of complex formations such as high temperature, high pressure and multi-pressure systems, the application range of high-density drilling fluid is becoming wider and wider. Drilling fluid is an important part of drilling engineering, and its performance is directly related to the drilling quality, drilling cost and drilling cycle of deep and ultra-deep wells. Compared with water-based drilling fluids, high-density oil-based drilling fluids have incomparable advantages in anti-slumping, lubrication, anti-seizing, and anti-pollution. However, in the act...

AI Technical Summary

Problems solved by technology

Although the oil-based drilling fluid can reduce the viscosity of the high-density oil-based drilling fluid to a certain extent, its effect is still unsatisfactory, and the composition and preparation of the auxiliary emulsifier are relatively complicated, which is not conducive to popularization and application; and the high-density When the viscosity of oil-based drilling fluid is too low, the weighted material is easy to settle, and the performance of high-density oil-based drilling fluid is easy to change, which has a great impact on the stability of the wellbore in high-pressure formations

Therefore, the existing technology has a large room for improvement

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