Cement slurry for plugging and anti-gas channeling for cementing of small hole easily lost or narrow gap annular well

Abstract

The invention belongs to the technical field of oil-gas well cementing engineering and discloses anti-gas-channeling plugging cement slurry for slim-hole or narrow-gap annular easy-leaking well cementing. The anti-gas-channeling plugging cement slurry comprises 100 g of class-G oil well cement or 100 g of a mixture of class-G oil well cement and silicon powder, 8 g-10 g of anti-gas-channeling plugging agent, 6 g-8 g of fluid loss agent, 0.0 g-1.0 g of dispersing agent, 0.2 g-3.5 g of set retarder, 0.1 g-0.2 g of defoaming agent and 38.0 g-44.0 g of tap water. The anti-gas-channeling plugging cement slurry has the advantages that anti-leakage plugging time of the anti-gas-channeling plugging cement slurry at the borehole static temperature of 90-180 DEG C is shortened from more than 20 seconds in a conventional system to less than 10-15 seconds, the pressure bearing capacity is increased from 2-3 MPa in the conventional system to 5-6 MPa, an SPN value representing the anti-gas-channeling performance is less than 3, anti-impact toughness of set cement setting for 24 hours is more than 3.0 J / cm<2>, and excellent overall engineering performance coordination is achieved.

Description

technical field [0001] The invention belongs to the technical field of oil and gas well cementing engineering, and in particular relates to a plugging and anti-gas channeling cement slurry used for the cementing of slim well holes or narrow gap annulus wells. Background technique [0002] In the deep well section of a well with complex structure or in a new well with multi-pressure layers drilled from the side of an old well, the cementing process of a multi-pressure system with slim holes or narrow gap annulus is prone to leakage and oil-gas-water channeling during the waiting solidification process , the coagulated cement sheath is easily broken under the external force of subsequent operations, which affects the effective sealing quality between layers, and even causes pressure in the annulus, which affects not only perforation and testing, but also production management and workover operations of oil and gas wells. Therefore, the cement slurry cementing that is suitable ...

AI Technical Summary

Problems solved by technology

[0003] To sum up, the problems existing in the existing technology are: in the cementing of slim hole or narrow gap annulus well with multi-pressure systems with different pressures in the same open hole section, leakage is prone to occur during the waiting period after cementing, and easy to occur during the waiting setting process. The cement sheath is prone to fragmentation during gas channeling, pressure testing or mining, which affects the quality of isolation or pressure in the annular space, and affects the production life of oil and gas wells

At present, the main reason and difficulty for the coexistence of leakage, channeling, and fragility have not been effectively solved is that, on the one hand, to prevent leakage, it is often necessary to use longer fiber materials, which will easily lead to poor rheological properties of cement slurry, which cannot meet the requirements of slim boreholes. Or narrow gap annulus well cementing is easy to generate high pump pressure, which requires good rheological properties of cement slurry

On the other hand, fiber and elastic particle materials commonly used to prevent cement stones from being easily broken easily lead to poor rheological properties of cement paste and reduced strength of cement stones, and cannot meet the requirements of cement injection. High-strength sealing ability

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