Enhanced high-density ductile anti-channeling cement slurry for oil and gas well cementing

Abstract

The invention discloses a reinforced high-density tough anti-channeling cement paste for well cementation of an oil-gas well. Based on the weight of cement (100%), the reinforced high-density tough anti-channeling cement paste comprises the following components in percentage by weight: 22.5-24.0% of silica sand, 66.0-117.5% of iron ore powder, 8.9-11.9% of reinforcing agent, 10.0-12.5% of flexible anti-channeling agent, 1-1.25% of toughener, 2.0-2.5% of dispersing agent, 5.6-7.1% of fluid loss control agent, 2.0-2.5% of retarder, 0.2-0.25% of defoamer and 54.2-64% of water. The cement paste provided by the invention has favorable engineering properties, so that high-density set cement has the properties of high compression strength, low elasticity modulus and high tensile strength, and the mechanical properties of the set cement are effectively improved; and the cement paste can keep the integrity and the sealing property for oil-gas-water in a stratum for a long time, thereby effectively controlling secondary channeling.

Description

technical field [0001] The invention relates to an enhanced high-density toughness anti-channeling cement slurry for oil and gas well cementing, which belongs to the field of petroleum drilling engineering. Background technique [0002] Annulus channeling means that the fluid in the formation flows from the high-pressure layer to the low-pressure layer or the ground through the channeling channel (the cement sheath itself or the two interfaces of the annulus) under the action of the pressure difference, resulting in the mutual channeling of oil, gas, and water between the underground layers or Oil, gas and water are coming out of the wellhead. Annular channeling can be divided into the following two types: (1) annular channeling through the cement sheath itself; (2) annular channeling through the two interfaces. [0003] The micro-annulus and micro-cracks in the annulus are the root causes of channeling. When the casing is subjected to high temperature and high pressure (s...

AI Technical Summary

Problems solved by technology

However, the ductile anti-channeling cement slurry systems reported so far basically reduce the compressive strength of the cement slurry while obtaining a lower elastic modulus and high toughness. The lower compressive strength makes the cement sheath appear after compression. With a certain degree of plastic deformation, micro-annulus often appears when the pressure in the pipe decreases, which leads to the phenomenon of "annulus under pressure" in oil and gas wells, and it is difficult to ensure the long-term sealing performance of the cementing sheath under high impact loads in subsequent operations

In addition, for high-pressure deep wells, conventional density ductile cement slurry is obviously unable to meet the requirements of well cementing construction, and it is necessary to develop corresponding enhanced high-density ductile anti-channeling cement slurry

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