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An oil well cement, low-density technology, applied in the field of oil and gas well cementing, can solve the problems of insufficient early strength and short thickening time, and achieve the effect of improving stability and ensuring cementing quality.
Active Publication Date: 2019-05-14
JIAHUA SPECIAL CEMENT
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[0008] The present invention aims to solve the technical problems that the early strength of low-density cement is not high enough and the thickening time is short in the prior art, and provides a new low-density oil well cement, which can not only meet the requirements of early strength, but also has a longer thickening time. It can meet the special requirements for strength and densification in the special surface cementing environment, and realize the pressure stability requirements before, during and after cementing.
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Embodiment 1
[0031] A low-density oil well cement, composed of the following raw materials by mass percentage: 87.15% sulfoaluminate cement clinker, 6% anhydrite, 6% hollow glass microspheres, 0.1% dispersant CFR-H, 0.75% citric acid , the water-cement ratio is 0.50.
[0032] In the present embodiment, the specific surface area of gypsum is 462cm 2 / g, index of glass beads 0.5g / cm 3 , The specific surface area of sulphoaluminate cement clinker is 520cm 2 / g, anhydrous calcium sulfoaluminate C 4 A 3 The content is 57%.
Embodiment 2
[0034] A low-density oil well cement, composed of the following raw materials by mass percentage: 85% sulfoaluminate cement clinker, 4.2% anhydrite, 10% hollow glass microspheres, 0.3% dispersant FDN, 0.5% borax, water ash The ratio is 0.40.
[0035] In the present embodiment, the specific surface area of gypsum is 450cm 2 / g, index of glass beads 0.3g / cm 3 , The specific surface area of sulphoaluminate cement clinker is 470cm 2 / g, anhydrous calcium sulfoaluminate C 4 A 3 Content 60%.
Embodiment 3
[0037] A low-density oil well cement, composed of the following raw materials by mass percentage: sulfoaluminate cement clinker 84.6%, anhydrite 10%, hollow glass microspheres 5%, dispersant FDN 0.1%, citric acid 0.3%, water The gray ratio was 0.46.
[0038] In the present embodiment, the specific surface area of gypsum is 473cm 2 / g, index of glass beads 0.5g / cm 3 , The specific surface area of sulphoaluminate cement clinker is 500cm 2 / g, anhydrous calcium sulfoaluminate C 4 A 3 Content 55%.
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Abstract
Belonging to the technical field of oil-gas well cementing, the invention discloses a low-density oil well cement. The oil well cement comprises the following raw materials by weight percentage: 82-90% of cement clinker, 1-8% of gypsum, 5-10% of hollow glass beads, 0-0.3% of a dispersant, and 0.5-0.8% of a retarder. The cement clinker is one of sulphate aluminium cement clinker and high belite sulphoaluminate cement clinker. The sulphate aluminium cement clinker has a specific surface area of 470-520cm<2> / g; and the content of anhydrous calcium sulfoaluminate C4A3Sbar in the sulphate aluminium cement clinker is 50-75%. The cement provided by the invention is mainly used for offshore drilling operations of shallow strata, has high early strength and long thickening time, and can meet the requirements of pressure stability before cementing, during cementing and after cementing.
Description
technical field [0001] The invention relates to a low-density oil well cement, which belongs to the technical field of oil and gas well cementing. Background technique [0002] During the drilling operation, if a shallow gas blowout occurs, it will bring more serious results, especially in offshore drilling operations, when the blowout is severe, it will cause bowl-shaped subsidence at the surface, loss of ships and platforms, etc. The shallow lithology is loose and the pressure bearing capacity is low, resulting in a narrow pressure window and difficult pressure stability control. The shallow formation temperature is low, the cement slurry hydration rate is slow, and the early strength of cement stone is low, which intensifies the risk of gas channeling. The surface annulus The cement slurry with large volume, low displacement efficiency, and isolation of upper shallow gas is seriously damaged by drilling fluid, so it is difficult to ensure good cementation of cement stone....
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