Deepwater well cementing mortar architecture

Abstract

The present invention provides one kind of cement slurry system for deep water well cementing. The cement slurry system consists of silicate-sulfoaluminate composite cement 100 weight portions, hollow bead 0-100 weight portions, water loss reducing agent of hydroxyethyl cellulose or carboxymethyl hydroxyethyl cellulose 1.5-3.0 weight portions, dispersant of sulfonated formaldehyde-acetone polycondensate or sulfonated formaldehyde amidate-acetone polycondensate 0.3-1.0 weight portion, early strength agent of inorganic salts 2.0-4.5 weight portions, setting retarder of low molecular organic acids 0.1-1.2 weight portions, and water 60-120 weight portions. It has excellent low temperature early strength and 'rectangular thickening' performance, and possesses broad application foreground in deep water well cementing.

Description

technical field [0001] The invention relates to a deep-water well cementing cement slurry system, which is particularly suitable for low-temperature, shallow water-gas channeling flow cementing operations under deep-water conditions. Background technique [0002] Deep water refers to sea areas with a water depth of 500-1500m. In recent decades, the total number of large oil fields discovered worldwide has shown a downward trend, but the discovery rate of large deep-water oil fields has increased rapidly. Among the 58 major oil and gas discoveries in the decade from 1990 to 1999, about 1 / 3 were In deep waters. In recent years, deep-water oil and gas discoveries accounted for 40% of the total oil and gas discoveries in the world, especially in 2002-2003, it rose to 65%. At present, there are about 9.2 billion proven reserves in the deep waters of 18 basins on 6 continental shelves. m 3 Oil equivalent, it is estimated that there are about 13.6 billion m 3 Unproven reserves....

AI Technical Summary

Problems solved by technology

Irregular well diameters, large annular gaps and narrow density "windows" in deep water surface sections make it difficult to remove mud cake, and cementing tends to take on a "sandwich" structure, which seriously affects the cementation quality of the cementing interface

[2] There is a risk of channeling

[3] The combination of shallow water-air flow, low temperature and low density makes the risk of cementing channeling higher

Although the strength of high-alumina cement develops rapidly at low temperature, it has a small foothold in the later stage of strength decline; the ultra-fine cement + G-grade cement or A, H-grade cement + coagulant system is difficult to Get good anti-channeling ability and early strength