Method and device for measuring rigidity of underground shale cleavage surface

Abstract

The invention provides a method and device for measuring the rigidity of an underground shale cleavage surface. The method comprises the steps that a horizontal cleavage surface rock core normal stress-displacement curve, a vertical cleavage surface rock core normal stress-displacement curve and a horizontal cleavage surface rock core shearing stress shearing displacement curve under different stresses are obtained; calculating the normal deformation of the shale cleavage surface according to the horizontal cleavage surface rock core normal stress-displacement curve and the vertical cleavage surface rock core normal stress-displacement curve; fitting the normal deformation of the shale cleavage surface with the normal stress to obtain the normal rigidity of the shale cleavage surface; andfitting the tangential stiffness stress curve of the shale cleavage surface to obtain the relationship between the tangential stiffness and the normal stress of the shale cleavage surface. By means ofthe method for measuring the rigidity of the underground shale cleavage surface, the rigidity values of the shale cleavage surface in different time domains can be obtained only by finding the linearrelation between the normal stress and the rigidity of the shale cleavage surface, and the defect that the calculation error is large due to the fact that a fixed rigidity value is adopted in traditional engineering calculation is overcome.

Description

technical field [0001] The present application relates to the field of oil and gas drilling and completion, in particular to a method and device for measuring the stiffness of downhole shale bedding planes by using normal stress characterization. Background technique [0002] Shale gas reservoirs are typical bedding-like anisotropic formations, showing strong anisotropy in terms of mechanical properties and strength properties. The ground affects the stability of the wellbore. During the drilling process, complex situations such as lost circulation, wall collapse, block loss, and pipe sticking are prone to occur. Well diameter expansion and well wall instability are common and difficult problems in field production. Therefore, Accurate acquisition of mechanical parameters of shale bedding planes is a key link to realize safe design and ensure smooth drilling. The use of fixed shale bedding surface stiffness values ​​in traditional engineering calculations leads to large cal...

AI Technical Summary

Problems solved by technology

[0003] The present application provides a method and device for measuring the stiffness of shale bedding planes downhole to at least solve the problem of large errors caused by the calculation of fixed shale bedding plane stiffness values ​​in the prior art

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