High-temperature-resistant gel plugging agent for oil-based drilling fluid as well as preparation method and application of high-temperature-resistant gel plugging agent

Abstract

The invention provides a high-temperature-resistant gel plugging agent for an oil-based drilling fluid as well as a preparation method and application of the high-temperature-resistant gel plugging agent. The gel plugging agent is prepared from the following raw materials in parts by weight: 15-30 parts of gel, 2-7 parts of a cross-linking agent, 0.3-1 part of an initiator and 60-80 parts of baseoil, wherein the gel is a combination of two or more than three of diethylene glycol dimethacrylate, pentanediol diacrylate, hexadecyl methacrylate and polyurethane resin, and the cross-linking agentis two or three of dibutyl ammonium oleate, zinc acrylate and divinyl benzene. The plugging agent disclosed by the invention enters a crack under the action of pressure difference and is automaticallygelatinized to form high-strength and high-temperature-resistant gel, so that the crack is plugged; the plugging agent is good in oil-based drilling invasion resistance, can act on cracks within a certain width range, has a good plugging effect on malignant leakage, and has the advantages of being resistant to high temperature, high in volume expansion speed, high in gel forming strength, controllable in gel forming time and the like.

Description

technical field [0001] The invention relates to an anti-high temperature gel plugging agent for oil-based drilling fluid, a preparation method and application thereof, and belongs to the technical field of drilling fluid plugging. Background technique [0002] In order to ensure the safety, speed and efficiency of the drilling process, the bottom hole pressure must be kept higher than the formation pressure during drilling, and this pressure difference will lead to the loss of drilling fluid when drilling into permeable or fractured formations. Loss of drilling fluid leads to the loss of a large amount of drilling fluid, which increases the drilling cost; and the lost drilling fluid will destroy the permeability of the reservoir and reduce the oil and gas field recovery after entering the formation, which is a problem that must be faced in oil and gas exploitation. [0003] Existing plugging technologies, such as bridging plugging, curable plugging and polymer plugging, have...

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Problems solved by technology

For example: Chinese patent document CN105646763A provides an oil-based gel plugging agent, which is composed of the following raw materials in parts by weight: 20-40 parts of styrene, 2-10 parts of biodiesel, 0.5-5 parts of divinylbenzene, dimethyl 0.1-5 parts of diethylene glycol acrylate and 0.01-1 part of azobisisobutyronitrile, but the volume expansion rate of the above-mentioned oil-based gel plugging agent is low, and the plugging effect is good when facing cracks of 3mm and above bad

Chinese patent document CN105199693A provides an oil-based gel plugging slurry, which is composed of 35-70 parts of base oil, 5-25 parts of curing agent, 0.1-1 part of activator, 0.5 -4 parts of water, 0-60 parts of weighting agent, the base oil is at least one of castor oil, soybean oil, rapeseed oil, peanut oil, animal oil, fatty acid methyl ester, dimethyl maleate, Described curing agent is at least one in calcium oxide, magnesium oxide, zinc oxide, sodium carbonate, sodium bicarbonate, magnesium carbonate, sodium acetate, and described activator is potassium hydroxide, sodium hydroxide, sodium carbonate, At least one of potassium carbonate, and the weighting agent is at least one of barite, limestone, and iron ore powder, but the gel formed by the oil-based gel plugging slurry has poor temperature resistance and cannot be applied to High temperature formation, and can't seal malignant leakage

[0006] At present, gel plugging agents suitable for oil-based drilling fluids generally have defects such as low gel strength and poor temperature resistance, and cannot be used in ultra-high temperature formations.

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