Whole-process leakage-plugging and well-cementing design method for high-temperature and high-pressure ultra-deep well

Abstract

The invention discloses a whole-process leakage-plugging and well-cementing design method for a high-temperature and high-pressure ultra-deep well. The whole-process leakage-plugging and well-cementing design method sequentially comprises the following steps: A, pigging, calculating the annular total circulating pressure loss during pigging circulation, and using the annular total circulating pressure loss as stratum pressure bearing capacity; B, according to the stratum pressure bearing capacity, calculating the running speed of a casing pipe or a tail pipe, and then running a casing pipe string or a tail pipe string; C, according to the stratum pressure bearing capacity, calculating the drilling fluid circulating displacement after running the casing pipe or the tail pipe, and then circulating a drilling fluid; D, calculating the flow-plugging critical displacement during cement-injecting operation; E, calculating the safe critical displacement during the cement-injecting operation; F, according to the flow-plugging critical displacement and the safe critical displacement during the cement-injecting operation, determining the actual operation displacement, performing the flow-plugging and cement-injecting operations, and sequentially injecting a spacer fluid, a cement slurry and a slurry replacing fluid. By the whole-process leakage-plugging and well-cementing design method, guidance can be provided for plugging and well cementation of deep and ultra-deep wells so as to ensure that the ultra-deep well cementing operation is successful and improve the well-cementing quality.

Description

technical field [0001] The invention relates to a design method for plug-flow leak-proof cementing in the whole process of high-temperature, high-pressure ultra-deep wells in the process of oil and gas exploration and development. Background technique [0002] A continuous and complete cement sheath with excellent performance is the key to the long-term sealing ability of a high-temperature, high-pressure ultra-deep wellbore, and the cementing quality directly determines and affects the integrity of the cement sheath. However, as exploration and development continue to move towards deep formations, the actual geological conditions of the operation are complex, and the cementing operation often faces serious leakage problems, which makes it difficult for the cement slurry to go back up and fill the annular space at one time. Poor quality, discontinuous cement sheath. In order to reduce the leakage during the cementing process, reducing the operating displacement is an effect...

AI Technical Summary

Problems solved by technology

At present, most plug flow cementing designs are based on the design of plug flow displacement, and the design of casing running speed and drilling fluid circulation displacement is calculated based on the annulus return velocity at the drill collar during drilling using empirical formulas as a reference. Combined with the calculation of the actual pressure bearing capacity of the formation, resulting in leakage before cementing, causing adverse effects on subsequent cementing operations

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