Fresh water salt-resistant tough cement paste for gas storage

Abstract

The invention discloses a fresh water salt-resistant tough cement paste system for a gas storage. The system comprises, by weight, 100 parts of G-grade cement, 42 parts of fresh water, 0.3-0.5 part of an acetone-formaldehyde condensate dispersant, 3-3.5 parts of a modified rubber powder elastic agent, 0.3-0.5 part of an aluminum powder gas expansion agent, 4-5 parts of a fluid loss agent ZYJ-1L, 0.1-0.2 part of basalt fiber, 0.5-1.5 parts of a polyaluminum chloride compounded aluminosilicate salt-resistant coagulant, and 0.2-0.3 part of polyether defoaming agent. The G-grade oil well cement, the salt-resistant fluid loss agent, the salt-resistant coagulant, the expanding agent, the elastic agent, the fiber, the dispersing agent and other admixtures are mixed with fresh water, so that the performance of the cement paste is improved, and the cement paste is stable in performance under the erosion of 9% and 18% salts, is successfully applied to a gas storage in the ven-23, and meets the construction requirements of the gas storage.

Description

technical field [0001] The invention relates to the technical field of oil and natural gas well cementing cement slurry, in particular to a fresh water salt-resistant tough cement slurry for a gas storage with a salt layer as a capping layer. Background technique [0002] As the country's demand for clean energy increases, the consumption of natural gas as a clean energy is increasing. The characteristic of its use is that the consumption in winter is much larger than that in summer, and the gas storage has a good peak-shaving effect, which can effectively alleviate the Natural gas supply problems. Zhongyuan Oilfield is located in the natural gas peak shaving center in North China. The construction of the Zhongyuan gas storage is to use a thick salt layer with a thickness of 200-500m as the caprock, which can effectively prevent the loss of the stored gas. During the production process of the gas storage, high-pressure gas injection and low-pressure production Gas, the ceme...

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Problems solved by technology

Patent CN107794012A discloses a toughened expansive cement slurry for gas storage well cementing, using a toughening agent compounded of modified styrene-butadiene rubber and polypropylene fiber, and a modified PVA fluid loss reducer of polymer latex Although micro-expansion, high strength, and low elastic modulus have been achieved, the salt resistance of the system is not strong. Under the erosion of salt, the cement slurry will take a long time to consolidate after hydration reaction, and even lose strength. In practical applications, salt The good and good rate of layer sealing was less than 25%, which caused the Wen 23 gas storage to be shut down for two months

Patent CN1919963A is suitable for brine cement slurry of salt cavern gas storage. The system has added brine with a concentration of 15% to 18%. The system has a long thickening time and high brittleness of cement stone. It is easy to cause the cement sheath seal to fail and affect the life of the gas storage

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