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Method for evaluating elasticity of oil well cement stone

A technology for oil well cement and cement stone, which is applied in the preparation of test samples, the application of stable tension/pressure to test the strength of materials, sampling, etc. , the effect of simple experiment and low cost

Inactive Publication Date: 2016-07-20
SOUTHWEST PETROLEUM UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there is no index to characterize the elasticity of cement stone in China, and there is no method for evaluating the elasticity of oil well cement stone

Method used

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  • Method for evaluating elasticity of oil well cement stone
  • Method for evaluating elasticity of oil well cement stone
  • Method for evaluating elasticity of oil well cement stone

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] The G-grade cement of factory A has undergone two kinds of elastic toughness transformations, A and B, and formed A-type elastic cement and B-type elastic cement. The A and B elastic cements are used to prepare 1.45g / cm 3 The cement slurry system was tested at a temperature of 60°C and a pressure of 20.7MPa to evaluate the effect of elastic modification. With the evaluation method of the present invention, 3 curing times of 2 days, 7 days and 14 days are designed, and the uniaxial compression experiment of cement stone is done with the high-temperature and high-pressure rock triaxial instrument RTR1000 of U.S. GCTS company without enclosing. The elasticity of the two modified cements was compared with the original slurry, the experimental data are shown in Table 1, and the comparison conclusions are as follows image 3 .

[0040] Table 1. Experimental data for evaluating the elastic transformation effect of Grade G cement in Plant A (the density of cement slurry is 1.4...

Embodiment 2

[0043] The G-grade cement of Plant B has undergone two elastic toughness transformations of C and D to form C-type elastic cement and D-type elastic cement, and the C and D elastic cements are used to prepare 1.90g / cm 3 The cement slurry system was tested at a temperature of 60°C and a pressure of 20.7MPa to evaluate the effect of elastic modification. With the evaluation method of the present invention, 3 curing times of 2 days, 7 days and 14 days are designed, and the uniaxial compression experiment of cement is done with the high-temperature and high-pressure rock triaxial instrument RTR1000 of U.S. GCTS company without enclosure, and C, D The elasticity of the two modified cements was compared with the original slurry, the experimental data are shown in Table 2, and the comparison conclusions are as follows Figure 4 .

[0044] Table 2 The experimental data of the evaluation of the elastic transformation effect of G grade cement in Plant B (the density of cement slurry is...

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Abstract

The invention discloses a method for evaluating elasticity of oil well cement stone. The method comprises the following steps: (1) preparing and prefabricating cement paste for contrast, and pressing and curing to obtain cement stone; (2) drawing an axial stress-axial strain-radial strain-volume strain curve of the cement stone; (3) calculating Young modulus of the cement stone, thereby acquiring flexibility; (4) confirming an elastic strain limit of the axial strain through a knee point of the volumetric strain curve of the cement stone, drawing a vertical line to a horizontal axis from the elastic strain limit point, thereby forming a triangle by the vertical line, the axial strain curve and the horizontal axis, and calculating the area of the triangle, thereby acquiring elastic strain energy; (5) taking the flexibility as a horizontal coordinate and the elastic strain energy as a vertical coordinate, drawing a rectangular coordinate system, wherein a first quadrant is taken as a cement stone elasticity chart; and (6) dividing an elasticity comparison region on the elasticity chart at an elasticity coordinate point of certain cement stone and comparing elasticity magnitudes. According to the method provided by the invention, the elastic effects of common oil well cement and elasticity and toughness modified cement are directly and clearly evaluated; the test is simple; the cost is low; the popularization is easy.

Description

technical field [0001] The invention relates to an evaluation method for the elasticity of cement stone formed after oil well cement is solidified, and is mainly used for evaluating the elasticity of elastic cement, flexible cement, tough cement or elastic tough cement formed after ordinary oil well cement is modified through elastic toughness. Background technique [0002] The integrity of the cement sheath in oil and gas wells plays a key role in maintaining interlayer isolation, preventing oil and gas water channeling in the annulus, and avoiding pressure in the annulus. In the process of oil and gas well construction and post-production, the cement sheath has to bear the stress directly or indirectly caused by a series of working conditions such as pressure test, wellbore working fluid density change, well completion, perforation, oil test, fracturing, and production. The thermal stress effect caused by temperature changes in working conditions, especially for gas storag...

Claims

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Application Information

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IPC IPC(8): G01N3/08G01N1/28
CPCG01N1/286G01N3/08
Inventor 刘健李早元张兴国程小伟李明郭小阳
Owner SOUTHWEST PETROLEUM UNIV
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