This invention can be used in petroleum, civil, and geotechnical engineering for mechanical characterization of shale materials with field and in-situ logging tools. Formations in the earth are characterized by stress conditions which vary with depth and whose principal directions are generally vertical and horizontal. Gathering information concerning the stress conditions is essential in various disciplines such as underground transportation and petroleum exploration.
Existing techniques for determining rock properties include analysis of core samples. This invention bypasses the costly coring operations by predicting the mechanical properties of rocks using the mineral compositions of the rocks attained from in-situ geochemical logging tools.
The invention utilizes the downhole Elemental Capture Spectroscopy (ECS) logging tool, or its equivalent, to optimize costs, standardize testing procedures, and provide mechanical material properties of downhole shale from mineralogy composition and physical properties such as density and porosity. ECS is a pulsed neutron spectroscopy logging tool capable of measuring relative elemental yields based on neutron-induced gamma ray spectroscopy. In addition to the mineral composition, porosity and rock density are part of the mathematical and physical models that can be used with the ECS log data.
- Decreases the need for core samples, thus limiting costly coring operations
- Optimizes costs by using the ECS log vis-a-vis more expensive alternative logging tools