A casing pipe pressure control well cementation process

Abstract

The invention discloses a casing pipe pressure control well cementation process, and belongs to the technical field of oil and gas development well cementation. The casing pressure control well cementation process sequentially comprises a casing running stage, a cement injection and displacement stage and a bump pressure and setting waiting stage. In the casing running stage, the cementing and displacing stage and the bumping and waiting stage, the well bottom circulation equivalent density of the narrow safety density window well section is kept between the pore pressure equivalent density and the rupture pressure equivalent density corresponding to the narrow safety density window well section by controlling the wellhead annulus pressure. In the well cementation process, the wellhead annulus pressure is controlled; the well bottom circulation equivalent density corresponding to the narrow safety density window well section is enabled to be between the pore pressure equivalent densityand the rupture pressure equivalent density; it is ensured that a weak pressure-bearing stratum is not pressed to leak while the oil and gas display layer is pressed stably, the casing well cementation construction risk of a narrow safety density window well section is reduced, the well cementation quality is improved, the well integrity is improved, and the development benefits are ensured.

Description

technical field [0001] The invention relates to the technical field of oil development cementing, in particular to a casing pressure-controlled cementing process. Background technique [0002] Casing cementing is the process of running the casing into the well, injecting cement into the annular space between the well wall and the casing, and sealing off the oil layer, gas layer and water layer in the wellbore after the cement solidifies to protect Oil and gas well casing, increasing the life of oil and gas wells, is one of the important links in oil and gas well drilling engineering. [0003] At present, the basic process of casing cementing is to run the casing into the preset position in the downhole, then use the double rubber plug method for cement injection and displacement construction, and then carry out bump pressure, and complete the casing cementing after the cement solidifies. Through the continuous improvement of cement slurry performance, including thickening t...

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Problems solved by technology

[0004] However, for formations with a narrow safe density window, the existing casing cementing process is likely to cause lost circulation or aggravate lost circulation, resulting in a drop in liquid column pressure, resulting in upward channeling of oil and gas in the lower well section, and low interface cementation strength. The cementing quality is unqualified; and it is not easy to press and stabilize the high-pressure layer, and oil and gas are easy to escape; in addition, the displacement efficiency is low, and the virtual mud cake, oil film and drilling fluid on the well wall and casing wall are difficult to clean during the cementing process

The above problems often lead to high safety risk of casing cementing in formations with high and narrow safety density windows, and it is difficult to guarantee the quality of cementing, which has a great impact on the integrity of oil and gas wells and the long-term safe development of oil and gas fields

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