Low-solid-content drilling fluid used for hydrocarbon bearing shaly sands and preparation method of low-solid-content drilling fluid

Abstract

The invention provides a low-solid-content drilling fluid used for hydrocarbon bearing shaly sands and a preparation method of the low-solid-content drilling fluid. The drilling fluid is prepared from, by mass, 2-5% of sodium bentonite, 0.1-0.3% of modified asbestos, 0.5-0.8% of sulfonated bitumen, 0.1-0.3% of sodium carboxymethylcellulose, 0.1-0.3% of a basicity control agent, 0.7-1.0% of carboxymethyl starch ether, 0.2-0.4% of potassium polyacrylamide, 0.1-0.4% of glycidyl trimethyl ammonium chloride, 1-5% of a weighting agent and the balance water. The drilling fluid has the advantages of being low in solid content, low in density, low in fluid loss, high in inhibitive ability and good in rheological property. Dispersion of drilling cuttings can be effectively controlled, the density ofthe drilling fluid is conveniently controlled to be increased, the formation damage is small, the oil layer can be protected, and the drilling fluid is particularly suitable for the low-permeabilityhydrocarbon bearing shaly sands.

Description

technical field [0001] The invention relates to the field of drilling fluid in the process of oil and natural gas exploration and development, in particular to a low-solid phase drilling fluid used in argillaceous sandstone oil layers and a preparation method thereof. Background technique [0002] The muddy sandstone oil layer has strong drillability, and in order to obtain faster drilling speed, PDC bit is usually used for drilling. Because the rock-breaking mechanism of PDC bit is different from that of roller cone bit, the cuttings are fine and the cuttings concentration is high, and they are easier to disperse into finer cuttings, which are difficult to coat under the condition of limited drug dosage, which is easy to cause Inferior mud cannot be settled in the ground grit chamber, the concentration of drill cuttings is high, the drilling fluid is turbid, and the density of the drilling fluid rises rapidly, resulting in difficulties in drilling fluid density and solid ph...

AI Technical Summary

Problems solved by technology

Because the rock-breaking mechanism of PDC bit is different from that of roller cone bit, the cuttings are fine and the cuttings concentration is high, and they are easier to disperse into finer cuttings, which are difficult to coat under the condition of limited drug dosage, which is easy to cause Inferior mud cannot be settled in the ground grit chamber, the concentration of drill cuttings is high, the drilling fluid is turbid, and the density of the drilling fluid rises rapidly, resulting in difficulties in drilling fluid density and solid phase control in the horizontal section of the reservoir section of the high-inclination and extended-reach well. Oil layer is easy to be polluted

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