Method for evaluating quality of high-density water-based drilling fluid mud cake

Abstract

The invention relates to a method for evaluating quality of a mud cake formed in the drilling process of a high-density water-based drilling fluid system. The overall characteristics of the high-density water-based drilling fluid mud cake can be well evaluated so as to provide evidence for instructing the quality control of the mud cake. The problems such as stability of a well wall, underground safety and protection of an oil-gas reservoir caused by the poor quality of the drilling fluid mud cake can be reduced or eliminated. A technical scheme is as follows: the method comprises the following steps: first taking out a drilling fluid mud cake formed by drilling fluid in a high-temperature high-pressure filtration instrument, placing the drilling fluid mud cake in a mud cake test instrument, testing parameters Hc, Hd, Hs, Pi and Pf, and drawing a strength-thickness curve; placing the drilling fluid mud cake into a medium-pressure filtration instrument, measuring Kf, and evaluating overall characteristics of the quality of the mud cake according to the strength-thickness curve as well as an actual thickness, flexibility, compactness, smoothness, strength and lubricating property; and finally obtaining an evaluation conclusion and a comprehensive evaluation report. The method has good instruction significance for the on-site construction and is used for evaluating the quality of the high-density water-based drilling fluid mud cake.

Description

technical field [0001] The invention relates to a high-density water-based drilling fluid mud cake quality evaluation method for the mud cake formed during the drilling process of a high-density water-based drilling fluid system, which can better evaluate the overall quality of the high-density water-based drilling fluid mud cake The characteristics provide a basis for guiding the quality control of mud cake. Background technique [0002] In the process of drilling with high-density water-based drilling fluid system, the drilling fluid is required to form a thin, tough and dense high-quality mud cake, which has a low impact on drilling tools, drill bits, bottom hole assembly and embedded cuttings Or almost zero affinity. However, the important index of mud cake quality is often underestimated and not paid enough attention to. For example, when measuring the water loss of the high-density water-based drilling fluid system, it is only required to reduce the water loss blindl...

AI Technical Summary

Problems solved by technology

However, until today, the evaluation and determination of mud cake quality is still limited to scale ruler measurement, needle penetration method and artificial observation method. The instruments are only limited to indoor research, with few desirable parameters, crude and rough evaluation methods and standards, lack of scientificity and operability, and cannot be used to guide on-site production

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