Ultrahigh-strength tough cement paste system for well cementation as well as preparation and application thereof

Abstract

The invention provides an ultrahigh-strength tough cement slurry system for well cementation and preparation and application thereof. The ultrahigh-strength tough cement slurry system for well cementation comprises the following raw materials: 100 parts by weight of cement, 20-40 parts by weight of a high-temperature reinforcing material, 0.5-6 parts by weight of an inorganic toughening material, 0.5-4 parts by weight of a suspension stabilizer, 2-6 parts by weight of micro silicon, 0.5-1.5 parts of a dispersing agent, 2-6 parts of a fluid loss agent, 1-8 parts of a retarder, 0.2-1 part of a defoaming agent and 40-60 parts of clear water. The cement paste system is good in flowability and sedimentation stability, low in water loss, adjustable in thickening time and wide in adaptive temperature range; the set cement has the characteristics of ultrahigh strength and the like, well cementation requirements of deep shale gas, high-temperature deep wells and the like can be well met, set cement strength decline caused by high-temperature strength can be avoided, and the service lifetime of an oil-gas well can be further prolonged.

Description

technical field [0001] The invention relates to an ultra-high-strength ductile cement slurry system for well cementing and its preparation and application, and belongs to the technical field of deep shale gas and high-temperature deep well cementing slurry. Background technique [0002] With the advancement of drilling technology and the continuous deepening of oil and gas exploration and development, deep shale gas and high-temperature deep well cementing are gradually increasing. The difficulties in cementing under high-temperature conditions are mainly reflected in the following aspects: (1) The cement slurry has poor settlement stability and During construction, the solid phase is easy to settle and cause potential safety hazards; (2) The water loss of cement slurry becomes larger, even uncontrollable, and the construction risk increases; (3) The amount of retarder is large, and the thickening time is not easy to adjust; (4) ) The strength of cement stone is easy to decl...

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Problems solved by technology

For example, Chinese patent CN 106833567A discloses a high-strength, high-toughness, high-temperature-resistant cementing slurry system and its preparation method, which realizes high strength through the gradation of coarse quartz sand, fine quartz sand and nano-silica particles. The compressive strength is as high as 68MPa; however, the cement slurry system does not involve toughening materials, and the elastic modulus of cement stone is only reduced by the filling of nano-silica, and there is still a lot of room for improvement

Chinese patent CN 107777965A discloses a method for preparing high-strength and high-density cement slurry. This technology uses nano-barite to absorb the microporous structure of expanded vermiculite to form a dense polymer mortar composite. The cement strength is as high as 55MPa. However, this The technology only discloses data at 120°C, and does not involve higher temperature conditions

Chinese patent CN108439872A discloses a high-strength, low-elastic-modulus, high-density cement slurry that is resistant to high temperatures. It uses high-temperature reinforcing materials and hybrid nano-reinforced tougheners. The compressive strength of cement stone is as high as 57MPa, and the elastic modulus is less than 7GPa. The disclosed hybrid nano-reinforced toughening agent requires ultrasonic treatment for 30-50 minutes, which is not convenient for field cementing application

Chinese patent CN109761547A discloses a cementing slurry system suitable for large-scale staged fracturing of shale gas horizontal wells. This technology modifies the surface of rubber particles to enhance hydrophilicity. The elastic modulus of cement stone is less than 6GPa. However, The temperature resistance of rubber particles is poor, so it is difficult to apply high temperature deep well cementing

[0004] Although the existing technologies represented by the above patents have made breakthroughs in the cement slurry system, cement stone compressive strength, toughness modification, etc., there are still some problems in cementing operations under high-temperature conditions such as deep shale gas and high-temperature deep wells. question

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