Method for preparing fluid loss additive for drilling fluid

Abstract

The invention provides a method for preparing a fluid loss additive for drilling fluid. The fluid loss additive is mainly prepared from the following raw materials in part by weight: 30 to 35 parts of humic acid sodium, 20 to 30 parts of etherified starch, 10 to 15 parts of hydroxyethyl cellulose, 5 to 10 parts of polyacrylamide and 5 to 10 parts of water soluble silicone oil, preferably 30 parts of humic acid sodium, 25 parts of etherified starch, 10 parts of hydroxyethyl cellulose, 7 parts of polyacrylamide and 6 parts of water soluble silicone oil. The preparation method comprises the following steps of: heating the raw materials to 120 DEG C under sealing and stirring conditions and under the pressure of 0.8 to 1.2MPa, keeping the temperature for 8 to 10 hours to obtain a semi-finished product; and drying the semi-finished product at the temperature of between 85 and 100 DEG C, and adding 5 to 10 parts of sulfonated asphalt into the semi-finished product to obtain the fluid loss additive, wherein at the step of synthesizing the etherified starch, 50 to 80 parts of starch are soaked into 50 to 80 parts of 10-percent sodium hydroxide solution for swelling for 24 to 48 hours, the mixed solution is dried at the temperature of between 75 and 85 DEG C, the obtained product is ground to obtain the semi-finished product, 30 to 50 parts of chloroactic acid are added into 30 to 50 parts of the semi-finished product, the mixed solution is sealed and stirred, the pressure is controlled to be 0.8 to 1.2MPa, the PH value is adjusted to 7 to 8, and the mixed solution is heated to 135 to 145 DEG C and then kept at the constant temperature for 15 to 17 hours to obtain the etherified starch. The fluid loss additive possesses high anti-salt, anti-calcium and anti-high temperature properties, and has the effects of carrying drill cuttings and making mud cakes dense.

Description

technical field

[0001] The invention relates to the modification of the fluid loss reducer used in drilling fluid, so that the obtained fluid loss reducer has strong salt resistance, calcium resistance, high temperature resistance, low fluid loss, and can protect the oil layer from mud Pollution plays the role of carrying cuttings and making the mud cake compact. Background technique

[0002] During the drilling process of deep and ultra-deep wells, due to the influence of geothermal gradient and formation pressure gradient, the drilling fluid is under the condition of high temperature above 180°C for a long time, and there are high-temperature dispersion of clay, high-temperature degradation of organic polymer compounds, and high-temperature crosslinking of treatment agents. And other influences lead to poor rheological properties of drilling fluid and affect production, etc. In all kinds of drilling fluid treatment agents, the amount of fluid loss control agent is the firs...

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