InterPore2026

The effect of stratigraphic temperature on the fracture damage process of shale using the digital core technology

19 May 2026, 09:50

1h 30m

Poster Presentation (MS16) Complex fluid and Fluid-Solid-Thermal coupled process in porous media: Modeling and Experiment Poster

Speaker

Guoliang Li (Institute of Geology and Geophysics, Chinese Academy of Sciences)

Description

The effect of stratigraphic temperature on the fracture damage process of shale using the digital core technology

Shale gas is an unconventional natural gas resource that has received sustained interest due to its substantial reserves and broad value for integrated utilization. With the continued advancement of horizontal drilling and multi-stage hydraulic fracturing in horizontal wells, shale gas development in China has reached depths beyond 5,000 m, such that deep shale gas exploitation is now increasingly routine. The high-temperature and high-pressure environment of deep formations substantially complicates shale’s elastic mechanical response, fracture initiation/propagation. Consequently, a thorough characterization of the progressive failure behavior of shale under deep reservoir conditions is essential for robust evaluation of reservoir fracability and wellbore stability, and ultimately for guiding development decisions in unconventional gas reservoirs.
In this study, a temperature gradient ranging from 40 to 160 °C was established. Longmaxi Formation shale specimens with bedding oriented in the horizontal direction were selected for micron-scale X-ray CT–assisted in situ uniaxial compression tests. The temperature-dependent variations in key mechanical parameters, including peak strength, Young’s modulus, and peak strain, were quantified. Furthermore, the crack-propagation characteristics of shale at different failure stages under elevated temperatures were investigated in detail, thereby enabling an in-depth analysis of the underlying microscopic fracture mechanisms.
Five specimens were selected for heated in situ micro-CT uniaxial compression testing. The stress–strain curves from uniaxial compression tests conducted on specimens with bedding parallel to the loading direction at different temperatures are illustrated. The corresponding crack-propagation characteristics of individual specimens at different applied stress levels are listed in Table 1.
Figure 1 demonstrates that the fracture surface area increases with temperature, indicating a more complex failure morphology at higher temperatures. This may result from thermally induced stress heterogeneity arising from differential thermal expansion among constituent minerals, which promotes the generation of additional microcracks and, consequently, a larger fracture surface area upon failure.
Figure 2 shows that during the compaction stage, with increasing temperature, the ratio of the strain at the end of compaction to the peak strain decreases markedly. This indicates that temperature-induced expansion of mineral grains promotes partial closure of pre-existing cracks, thereby accelerating the compaction process. During the elastic stage, the ratio of the strain at the end of the elastic regime to the peak strain also shows a noticeable decrease with increasing temperature, especially when the temperature exceeds 120 °C. Similar to the compaction stage, this suggests that temperature exerts a limited influence on the elastic regime. During the stable cracking stage, the ratio of the strain at the end of stable cracking to the peak strain increases with temperature. This implies that elevated temperature enhances the apparent homogeneity of the specimens, bringing the dilatancy point closer to the peak point; accordingly, the stable cracking process is prolonged as temperature increases. During the unstable cracking stage, increasing temperature accelerates the unstable fracture process, as evidenced by the reduced separation between the dilatancy point and the peak point, leading to more rapid failure of the specimens.