1D mechanical earth modeling in the Permian Lucaogou Shale of the Santanghu Basin, Northwest China, from a complete set of laboratory data

Abstract

Understanding various properties of unconventional shale plays is important for successful field operations and development. We have comprehensively examined a total of 11 core plugs from the productive unit of the Middle Permian Lucaogou Formation in the Santanghu Basin with various experimental tools. Mineral assemblages were detected, and we found that samples are in the oil window with a combination of type I and II kerogens. After static and dynamic geomechanical analysis, we established a correlation between ultrasonic and static geomechanical parameters. The results indicated that the samples have a brittle behavior with hydrostatic compressive strength ranging from 177.68 to 419.63 MPa, and static Young’s modulus from 9.93 to 53.24 GPa. In the next step, using the measured data we calibrated the only existing well log from where the samples were retrieved and we built an 1D mechanical earth model throughout the entire target formation. Ultimately, by using partial least-squares regression analysis, we determined that feldspar and calcite are the main stiff minerals that would affect the mechanical properties positively, whereas clay minerals and organic matter could have a negative impact on the rock mechanical parameters.