Low-pressure easy-to-leak well cementing method and casing string

Abstract

The invention provides a low-pressure easy-to-leak well cementing method and a casing string, and belongs to the field of oil exploration. The method is characterized by adding a hydraulic stage collar and a hydraulic open hole packer into a well completion pipe string, cementing for the first time so as to isolate a leakage formation, and cementing for the second time so as to accomplish well cementing. The low-pressure easy-to-leak well cementing method provided by the invention is wide in application range, capable of effectively reducing the well cementing construction cost and shorteningwell cementing construction time, reducing the pressure-bearing leakage-stoppage cost, and effectively improving the easy-to-leak well cementing quality, and can provide effective guidance for the easy-to-leak well cementing construction.

Description

technical field [0001] The invention belongs to the field of petroleum exploration, and in particular relates to a cementing method and a casing string for a low-pressure well that is prone to leakage, and is especially suitable for a cementing process design method that does not return slurry during drilling or that leakage occurs after casing is run. Background technique [0002] Due to the low pressure bearing capacity of the formation, leakage is prone to occur during the drilling process. In order to meet the requirements of cementing construction, it is usually necessary to use plugging technology to improve the pressure bearing capacity of the formation, resulting in an increase in the cost of drilling engineering; at the same time, due to the low pressure bearing capacity of the formation, Leakage in the cementing construction process leads to the high return of cement slurry that cannot meet the design requirements, affecting the quality of cementing, which in turn s...

AI Technical Summary

Problems solved by technology

[0005] However, the above-mentioned existing methods have the following disadvantages: (1) it is difficult to adopt the technique of improving the pressure bearing capacity of the wellbore, there are many uncertain factors, and at the same time, the investment is large, which affects the drilling cycle; (2) the use of low-density cement slurry is costly, and at the same time The range of reducing cement slurry density is limited, and it cannot meet the cementing requirements of leakage wells after casing running; (3) the forward injection and reverse extrusion process is adopted, which is low in cost, but the construction period is long, and secondary back extrusion is usually required, and the cementing quality is poor. Difficult to guarantee, and it is difficult to connect the cement slurry for two cementing operations at the same time

Therefore, the current cementing technology and methods are difficult to effectively solve the technical problem of leakage prevention in low-pressure leaky well cementing

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