Drilling fluid

Abstract

The invention discloses a drilling fluid, which comprises bentonite, a high temperature resistance increased cutting fluid loss agent, a high temperature resistance viscosified fluid loss agent, a shale inhibitor, hollow glass microballoon and water. The drilling fluid has the advantages that the drilling fluid with low density possesses good stability, the high resistance capability can reach 180 DEG C, the drilling fluid possesses the effects of lubrication, collapse resistance and oil gas layer protection, no fluorescence is generated, no toxic pollution is generated, the environmental protection performance is good, and the preparation method is simple and easy to carry out.

Description

technical field [0001] The present application relates to drilling fluids, and more particularly to a water-based drilling fluid. Background technique [0002] CBM reservoirs in China are characterized by low permeability, low pressure and low water saturation. These characteristics determine that if effective measures are not taken during the drilling and completion process, the reservoir will be greatly damaged, resulting in a decrease in permeability and a decrease in CBM production. [0003] Reducing the density of drilling fluid, thereby reducing the invasion of drilling fluid into the reservoir, is an important measure to protect the coalbed methane reservoir and increase the production of coalbed methane. There are generally two processes for reducing the density of drilling fluid: aeration and foaming, which convert conventional drilling fluid into aerated drilling fluid or foam drilling fluid. However, these drilling fluids containing a certain amount of gas often...

AI Technical Summary

Problems solved by technology

However, these drilling fluids containing a certain amount of gas often encounter the following problems during use: (1) equipment such as air compressors is required, which increases the cost of drilling equipment; (2) pulse signals will rapidly decay in aerated drilling fluids , causing certain difficulties to conventional MWD operations; (3) If the gas contains oxygen, it is easy to cause corrosion of drilling tools, and even cause downhole fire or explosion; (4) Drilling fluid containing gas has strong compressibility, and its multiphase Flow characteristics bring great difficulties to hydraulic calculations

However, the existing low-density drilling fluids have weak temperature resistance, generally around 120°C, which cannot meet the requirements of deep well drilling. Therefore, it is necessary to develop high-temperature-resistant low-density drilling fluids to meet the needs of high-temperature and low-pressure formation drilling.

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