Lost circulation material for malignant loss and preparation method

Abstract

The invention relates to a lost circulation material for effectively plugging fractured and crushed stratum malignant loss in the drilling process and a preparation method. The invention adopts the technical scheme that a raw material for preparing the lost circulation material comprises the following components: 8 to 12 grams of hexadecyl dimethyl allyl ammonium chloride, 16 to 18 grams of acrylamide, 6 to 12 grams of styrene sodium sulfate, 0.2 to 0.4 gram of sodium dodecyl benzene sulfonate, 0.2 to 0.4 gram of potassium persulfate / sodium bisulfite, 16 to 20 grams of bentonite clay, and 239 to 279 grams of fresh water. The preparation method of the lost circulation material comprises the following steps of: firstly, dissolving recrystallized hexadecyl dimethyl allyl ammonium chloride, acrylamide and styrene sodium sulfate in the water; filling N2, adding an initiator and performing the reaction for 24 hours; precipitating, soaking and drying by using acetone so as to obtain white copolymer; and adding sodium dodecyl benzene sulfonate and bentonite clay into the copolymer and the water to obtain the lost circulation material. The lost circulation material can be used for plugging a leakage zone, has strong crushing resistance and strong temperature resistance and mineralization resistance degree and is suitable to be used for carrying out plugging on a big crack in the drilling process.

Description

technical field [0001] The invention relates to a plugging agent and a preparation method for effectively plugging the malignant leakage of fractured and fragmented formations during the drilling process. Background technique [0002] In recent years, the problem of lost circulation in oil and gas deep well drilling in western my country and northeastern Sichuan has become very prominent. The main characteristics are deep wells, piedmont structures, high and steep structures, containing hydrogen sulfide, and lost circulation is common. In eastern Sichuan, especially in the past 10 years, extensive oil and gas exploration and drilling have been carried out in high and steep structures, remote areas, and high mountain areas. According to statistics in recent years, almost every well drilled has different degrees of lost circulation; among them, general lost circulation accounts for more than 50%, and the success rate of one-time plugging is more than 70%; serious lost circulat...

AI Technical Summary

Problems solved by technology

[0005] The plugging of malignant leakage is very difficult. The technical difficulties of plugging of malignant leakage include the following two aspects: (1) The plugging agent is easily washed away by water. Generally, there is water (or mud) in formation fractures and caves, and the plugging fluid is generally Water base, when the two come into contact with each other, they will naturally mix, and the plugging agent will inevitably be diluted, which will make the plugging slurry less viscous and easier to flow away, and it will be more difficult for the plugging material to accumulate near the entrance of the leaky layer; After diluting, it is difficult to coagulate and solidify, or the coagulation strength is greatly reduced, and it is difficult to support the destructive effect of the leakage pressure difference, so that the plugging fails; Staying near the entrance Since all leakage stoppage agents must be fluid or must be carried by the fluid to reach the leaky layer, they will also be lost in large quantities when encountering such a leaky layer and flow into the deep part of the leaky layer instead of accumulating near the entrance of the leaky layer. It cannot play a plugging role at the entrance. The plugging agent can only be effective if it does not flow away once it enters the leaky layer, but stays near the entrance of the leaky layer, and then cements and hardens.

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