ZHAGN Hui, XU Ke, ZHANG Zhi-zhen, et al. Rock fracture criteria and evaluation methods for fracture development intensity in the strongly compressed formations of the Kuqa Depression[J]. 2026, 47(7).
ZHAGN Hui, XU Ke, ZHANG Zhi-zhen, et al. Rock fracture criteria and evaluation methods for fracture development intensity in the strongly compressed formations of the Kuqa Depression[J]. 2026, 47(7).DOI: 10.16285/j.rsm.2025.0854.
To address the challenges in quantitatively evaluating rock fracture evolution and fracture development intensity within the strongly compressed strata of the Kuqa Depression in the Tarim Basin
this study introduces a method for assessing fracture development intensity. This method is grounded in stress state analysis and is realized through a series of rigorous steps
including geological data analysis
rock mechanical testing
formulation of failure criteria
and development of computational software. The research reveals that deep-seated rocks in the Kuqa Depression exhibit high uniaxial compressive strength
low Poisson’s ratio
and brittle-dominated mechanical properties under intense compression. The failure criterion must account for the intermediate principal stress effect and confining pressure dependency. Building on octahedral energy theory
a generalized failure criterion is established
integrating tensile microcrack initiation and frictional slip coupling mechanisms. A four-level index system for fracture development intensity
centered on the relative fracture surface tensor distance
is proposed
along with supporting computational software. Validation using logging and core data from the Jurassic Ahe Formation in Wells DB5 and DT2 in the Kuqa Depression demonstrates a predictive accuracy exceeding 80% for fracture development intensity
which aligns well with imaging logging results. This method surmounts the constraints of conventional logging techniques confined to localized wellbore detection
enabling dynamic fracture evaluation across entire well sections and throughout their lifecycle. It provides a quantitative basis for optimizing stimulation strategies in ultra-deep hydrocarbon reservoirs under intense compression and for controlling wellbore stability.