A Method of Evaluating the Ability of Drilling Fluid to Stabilize Borehole Wall in Shale Formation Based on Acoustic-Electric Response

Abstract

The invention discloses a method for evaluating the ability of drilling fluid to stabilize the borehole wall of a shale formation based on acoustic and electric responses. The method comprises: drilling and taking cores from the shale formation to be drilled, and drying; calculating and measuring the density and longitudinal wave velocity of the sample , resistivity; put the sample in the aging tank or the high temperature and high pressure water loss instrument, add the drilling fluid to be evaluated, so that the drilling fluid should completely immerse the plunger core sample, and apply pressure so that the aging tank or the high temperature and high pressure water loss instrument is at Soaking temperature; after immersion, cool down, release the pressure, and take out the soaked sample; measure the length, diameter and mass of the sample soaked in drilling fluid, calculate the density, test the longitudinal wave velocity and resistivity of the sample, and calculate Acoustic-electric disturbance comprehensive index: According to the acoustic-electric disturbance comprehensive index, the ability of the drilling fluid to stabilize the borehole wall of the shale formation is judged. The method of the invention provides an efficient and reliable experimental method for drilling fluid performance design, performance optimization and drilling fluid formulation system optimization in shale formations.

Description

technical field [0001] The invention relates to an indoor evaluation method of drilling fluid, in particular to a method for evaluating the ability of drilling fluid to stabilize the borehole wall of a shale formation based on the acoustic-electric response. Background technique [0002] The collapse and instability of shale formations that are common in the drilling process greatly increases the downhole complex risk, prolongs the drilling cycle and increases the drilling cost. Major problems that have not been effectively resolved. [0003] The wellbore stability of shale formations is not only controlled by geomechanical characteristics such as formation rock mechanical strength and in-situ stress, but also depends on the stability properties such as inhibition and plugging of drilling fluid. Therefore, it is necessary to optimize and optimize the drilling fluid before drilling, so as to maintain the stability of the wellbore in the shale formation to the greatest extent...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a method for evaluating the ability of drilling fluid to stabilize the borehole wall of shale formations based on acoustic and electric responses, which solves the problem that the existing drilling fluid performance evaluation method has poor adaptability to the wellbore stability performance evaluation of shale formations and cannot be objective , Truly reflect the ability of the drilling fluid to stabilize the borehole wall, and the evaluation results are not accurate and reliable enough

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