Preparation method of starch grafted copolymer inverse emulsion for drilling fluid

Abstract

The invention relates to a preparation method of a starch grafted copolymer inverse emulsion for a drilling fluid. The method comprises the following steps of: adding an emulsifier sorbitan monooleate into white oil, and stirring, dissolving and introducing nitrogen to obtain an oil phase; dissolving potassium hydroxide in water, adding 2-acrylamidyl-2-methyl propanesulfonic acid, acrylamide, a vinyl monomer, a cationic monomer, polyoxyethylene sorbitan monooleate, ethylene diamine tetraacetic acid disodium salt and starch, and stirring to obtain an aqueous phase; adding the aqueous phase into the oil phase, adequately emulsifying, adjusting the pH value, introducing nitrogen, adding an initiator and a reducing agent; and stirring, heating, insulating heat, cooling, discharging and filtering under nitrogen protection to obtain the starch grafted copolymer inverse emulsion for the drilling fluid. The product serving as a drilling fluid treatment agent has good de-filtration effect, good thickening effect, a flow type regulating effect and good inhibition effect for dehydrating dispersion of clay and drillings, so that the quality of filter cakes is improved, the lubricity of the drilling liquid is improved and the processing cost of the drilling liquid is lowered, and the preparation method is suitable for various types of water-based drilling fluids.

Description

Technical field: [0001] The invention relates to a method for preparing a starch graft copolymer inverse emulsion for drilling fluid, and belongs to the technical field of preparation of water-soluble polymer materials. technical background: [0002] Starch modified products are cheap and abundant, and are an important oilfield chemical. As a drilling fluid treatment agent, it can be used as a fluid loss reducer for saturated brine drilling fluid because of its strong salt resistance, but its temperature resistance is poor, and it is easy to ferment when the bottom hole temperature is high. In addition to its promotion, multi-polymers such as acrylamide, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and acrylic acid have good temperature resistance, but the cost is high, which is not conducive to promotion. The starch graft copolymer has both the salt resistance of starch and the temperature resistance of polymer products, and is low in cost, which meets the needs of th...

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Problems solved by technology

[0003] However, the starch graft copolymer fluid loss control agents in the published achievements are all powders. Since the powdery treatment agent is directly added to the drilling fluid when used, not only can it not be added evenly, but the dissolution rate is slow. If the dissolution time is longer than the drilling fluid cycle , the polymer particles that are not dissolved or swollen will be sieved out from the vibrating sieve, or even paste the sieve. Therefore, it is necessary to prepare a glue solution with a mass fraction of 0.5% to 2% before use. When mixing the glue solution, it will not only increase the workload , and will cause the product to shear and degrade, which is not only inconvenient to use, but also affects the use effect of the product