Oil well cement paste system for preventing high-temperature strength retrogression and preparation method thereof

Abstract

The invention relates to an oil well cement paste system for preventing high-temperature strength retrogression and a preparation method thereof in the field of oil and gas field well drilling and cementing. The system comprises, by weight, 100 parts of cement, 25-45 parts of silica fume, 0-6 parts of a fluid loss agent, 0-5 parts of a retarder, 1-10 parts of a strength enhancer, 0.5-5 parts of asuspension stabilizer and 40-60 parts of water. The strength enhancer in the system is liquid, is low in dosage, can accelerate the strength development of set cement, and greatly improves the strength of the set cement without strength retrogression at high temperature. The system has a wide popularization and application prospect.

Description

technical field [0001] The invention relates to the field of drilling and cementing in oil and gas fields, and more particularly relates to an oil well cement slurry system for preventing high-temperature strength decline and a preparation method thereof. Background technique [0002] Cement stone is the main material constituting the cement sheath in the well, and has the function of protecting the casing. The downhole cement sheath is affected by the high-energy flow of the perforating bullet, and instantly bears the impact pressure of 3-4Gpa, and its stress wave forms a tensile force locally in the cement sheath. When the radial tensile stress of the cement sheath exceeds its limit, the cement sheath will rupture and form macroscopic cracks. In order to stabilize and increase production, various oilfields have successively carried out downhole engineering operations such as water injection, fracturing, acidizing, refilling, and increasing production pressure difference. D...

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Problems solved by technology

[0004] The Chinese patent with publication number CN106479461A provides a preparation method of high-strength cement slurry, which consists of the following components and parts by weight: 100 parts of cement, 23-35 parts of lightening agent, 30-40 parts of high-temperature strength stabilizer, 10-23 parts of filler, 1.5-2 parts of dispersant, 1-2 parts of early strength agent, 8-15 parts of fluid loss reducer; wherein, the lightening agent is floating beads; the high-temperature strength stabilizer is high-activity Silicon powder; the filler is micro silicon; the dispersant is aldehyde and ketone condensate or naphthalene-based dispersant; the components of the early strength agent are aluminum thiosulfate, sodium silicate, basic aluminum chloride, etc. Two or more of them are mixed; the fluid loss reducer is sulfonated acetone formaldehyde condensate, and the anti-high temperature decay agent is mainly aluminum thiosulfate, sodium silicate, and basic aluminum chloride; but It is mainly used in low-density cement slurry system, with large dosage, complex formula, poor compatibility with cement slurry admixture, and it is difficult to meet the application of oil well cement slurry engineering

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