Using the effect of core disking in field geomechanics

Abstract

Background. Experience in the development of shock-hazardous ore deposits in the CIS and other countries has shown that the tendency of an ore (rock) to accumulate elastic potential energy and to brittle fracture, as well as the proximity of the level of acting stresses to the ultimate strength of rocks, are reliably determined by the effect of fission of the rock core obtained during drilling wells with ring crowns, on convex-concave discs. The information obtained by core disking is a complex characteristic of the massif state. It reflects both the strengthproperties of the rock, and the degree of its fragility, and the magnitude of the stresses acting in the massif.

Aim. Checking the possibility of determining the acting stresses in a rock mass using the core disking method in preparing a geomechanical model for hydraulic fracturing design.

Materials and methods. In order to test the method, we used core material taken from some deposits in Western Siberia. As disking intervals, core sections were selected that were broken into disks with a thickness of not more than half of its diameter. The magnitude of the stresses acting in the rock mass, normal to the borehole axis σmax, was determined in fractions of the ultimate strength of the rock in uniaxial compression σ0 by the ratio of the thickness of the disks to the core diameter t/d.

Results. It has been proven that the disking method allows to determine the lateral rock pressure in vertical oil wells, and can be used in the preparation of a geomechanical model for hydraulic fracturing design.

Conclusion. The possibility of using the effect of core disking to determine horizontal stresses when compiling a geomechanical model of a section for the purpose of designing a hydraulic fracturing process is considered. It isrecommended to study the strength properties of the core taken directly from disking intervals to ensure better convergence and accuracy of the results of the method.