Quantitative division method of geomechanical strata and its applications in exploration and development of oil and gas in ultra-deep layers

Abstract

Efficient exploration and development of ultra-deep oil and gas reservoirs are key objectives in current global energy geological research. The concept of "geomechanical strata and oil and gas exploration and development" represents a cutting-edge research area internationally. Establishing an effective method for dividing geomechanical layers holds both theoretical and practical significance for the efficient exploration and economical development of ultra-deep oil and gas reservoirs. Currently, the state of in-situ stress affects the effectiveness of natural fractures, while the development and distribution of fractures impact the mechanical properties of rocks, which influence the the distribution of in-situ stress. However, the existing "rock mechanical stratigraphy theory" fails to comprehensively cover the coupling relationships among these three factors. In response, this study introduced a method for the quantitative division of geomechanical strata based on six parameters: minimum horizontal principal stress, difference in horizontal stress, elastic modulus, angle between the current dominant stress orientation and the natural fracture orientation, natural fracture density, and stress concentration factor. An analysis of well W in the Dabei area of the Kelasu structural belt, Kuqa Depression, Tarim Basin, demonstrated that the target layers at the Cretaceous Bashijiqike Formation exhibited strong vertical geomechanical heterogeneity. The geomechanical strata of the reservoir correlated well with the development sections of the gas layers. Therefore, with the results of geomechanical strata division, it is possible to guide the optimization of sweet spots in ultra-deep oil and gas reservoirs.

Keywords

• geomechanical strata
• ultra-deep layers
• in-situ stress
• fractures
• rock mechanics
• exploration and development of oil and gas