Modified enteromorpha prolifera-based composite filtrate reducer for drilling fluid and preparation method thereof

Abstract

The invention discloses a modified enteromorpha prolifera-based composite filtrate reducer for drilling fluid. The composite filtrate reducer comprises modified enteromorpha prolifera, a temperature stabilizer, micron calcium carbonate, nano silicon dioxide and a dispersing agent. The preparation method comprises the steps: adding deionized water and the modified enteromorpha prolifera into a high-pressure homogenizer, homogenizing, adding the temperature stabilizer, and homogenizing; adjusting the pH value of the system, adding micron calcium carbonate, and continuing homogenizing; adding nano silicon dioxide, homogenizing, then adding the dispersing agent, and continuing homogenizing; and drying and crushing the product to obtain the modified enteromorpha prolifera-based composite filtrate reducer for the drilling fluid. After 2.0 wt% of the modified enteromorpha prolifera composite filtrate reducer prepared by the method is added into base slurry at normal temperature, the high-temperature and high-pressure (180 DEG C / 3.5 MPa) filtrate loss of the base slurry is reduced from 55 mL to 12 mL, the plugging rate of a 500 mD rock core is increased from 35% to 92%, and the treating agent is non-toxic, has no adverse effect on the environment and has acute toxicity EC50 greater than 30000.

Description

technical field

[0001] The invention relates to a fluid loss reducer for drilling fluid and a preparation method thereof. Specifically, during the drilling process, the drilling fluid needs to have a certain function of the fluid loss reducer, so as to reduce the penetration of the drilling fluid filtrate into the formation and avoid causing corresponding well wall instability. , reservoir damage and other issues. Background technique

[0002] The formations encountered during the drilling process are diverse, ranging from mudstone, shale, sandstone, limestone, carbonate rock and their composite rocks, with different porosity and permeability, and there may be fractures or In karst-cavity formations, at this time, the drilling fluid filtrate may enter the formation to a large extent. When the formation fluid and borehole wall rocks come into contact with the drilling fluid, it may cause wellbore instability, and in severe cases, may cause wellbore collapse. Therefore, it is...

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