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Evaluation method for hydration characteristics of layered hard brittle mud shale

A technology of mud shale hydration and evaluation method, which is applied in earth-moving drilling, analysis of solids using sonic/ultrasonic/infrasonic waves, wellbore/well components, etc. Micro-fractures swell in contact with water, etc., to achieve the effect of simple and easy-to-understand evaluation methods, prevention of wellbore instability, and high repeatability

Active Publication Date: 2015-06-03
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the core is crushed, the micro-cracks existing in the original core are destroyed, so this method ignores the expansion of the micro-cracks in the original rock when it encounters water, and cannot truly restore the expansion state of the rock
In particular, there are micro-fractures of graptolite in marine sedimentary shale, the width of which is extremely small and difficult to observe with the naked eye, but these micro-fractures are severely swelled by water.
In addition, in the process of evaluating the hydration characteristics of layered hard and brittle mud shale, there is no reasonable evaluation device at present, which leads to inaccurate evaluation results, large errors, and high cost

Method used

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  • Evaluation method for hydration characteristics of layered hard brittle mud shale
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  • Evaluation method for hydration characteristics of layered hard brittle mud shale

Examples

Experimental program
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Embodiment 1

[0057] Such as figure 1 As shown, a method for evaluating the hydration characteristics of layered hard and brittle shale includes the following steps in order:

[0058] Step 1: Describe the rock and take the core to prepare a core sample;

[0059] Step 2: Restore the core sample to the in-situ pore fluid saturation state of the formation;

[0060] Step 3: Test the longitudinal wave velocity and shear wave velocity of the core sample under the in-situ condition of the formation, then change the properties of the pore fluid, and test the longitudinal wave velocity and shear wave velocity of the core sample after changing the properties of the pore fluid;

[0061] Step 4: Evaluate the hydration characteristics of the layered hard and brittle shale according to the changes in the longitudinal wave velocity and the shear wave velocity of the core samples under different pore fluid properties.

[0062] In step 1, the rock has a set of joints, and the inclination angle between the joint surfa...

Embodiment 2

[0081] A method for evaluating the hydration characteristics of layered hard and brittle shale. The steps, principles, evaluation devices adopted, and beneficial effects are the same as those in the first embodiment. The difference is:

[0082] In step 1, drill three core samples. The shape of the core sample is cylindrical and the length is 3 times the diameter. After grinding, the diameter is 25mm and the length is 75mm. The diameter of the core sample is 20 times the diameter of the largest particle in the rock. Measure two mutually perpendicular diameters at the bottom, middle, and upper part of each core sample, and take the average of the measurement results, which is the final diameter of the core sample.

[0083] In step 2, the method to restore the core sample to the in-situ pore fluid saturation state of the formation is to prepare a potassium chloride solution with the same properties as the pore fluid in the in-situ formation state, and immerse the core sample in the ...

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Abstract

The invention discloses an evaluation method for hydration characteristics of layered hard brittle mud shale. The evaluation method comprises the following steps: describing the rock, then coring the rock, and preparing a rock core sample; restoring the rock core sample to a stratum in-situ porosity fluid saturation state; testing a longitudinal wave speed and a transverse wave speed of the rock core sample under the stratum in-situ state condition, then changing the porosity fluid character, and testing the longitudinal wave speed and the transverse wave speed of the rock core sample after the porosity fluid character is changed; evaluating the hydration characteristics of the layered hard brittle shale under the variation situation of the longitudinal wave speed and the transverse wave speed of the rock core sample under different porosity fluid character conditions. The evaluation method is simple, easy to understand, convenient to operate and capable of quantitatively evaluating the hydration characteristics of the rock, the scientific evidence can be provided for stably control of the well wall when the layered hard brittle mud shale is drilled, the instability of the well wall can be better prevented, and the underground complicated situation can be prevented.

Description

Technical field [0001] The invention belongs to the technical field of oil and gas drilling engineering, and relates to a method for evaluating the hydration characteristics of mud shale, in particular to a method for evaluating the hydration characteristics of layered hard and brittle mud shale. Background technique [0002] In recent years, the wellbore stability problem encountered when drilling stratified hard and brittle shale during drilling has been a major problem that plagues oil and gas drilling engineering. The layered hard and brittle shale has abnormal bedding development and high swelling clay content, which can easily lead to serious wellbore instability during drilling, such as wellbore shrinkage, wellbore collapse, drilling fluid loss and reservoir damage And other issues. Therefore, the evaluation of the hydration characteristics of the layered hard and brittle shale has important economic and social significance. [0003] At present, the evaluation method for t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00
CPCG01N29/07
Inventor 卢运虎陈勉董京楠金衍刘铭侯冰杜晓雨
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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