Implications of Temperature for the Modification of High-Overmature Shale Reservoirs: Experimental and Numerical Analysis

High-temperature pore reconstruction technology is a reservoir reconstruction measure that has emerged in recent years. It is of great significance to study the variation in pore structure characteristics of shale under high temperature for reservoir reconstruction. To study the effect of high temperature on shale pores, scanning electron microscopy (SEM) experiments and fluid injection experiments were used to analyze the variation of pore structure characteristics under high temperature. Studies have shown that temperature has a great influence on the morphology and distribution characteristics of shale pores. In particular, there is a temperature between 300°C and 400°C that is suitable for modifying pores. The distribution characteristics, surface area, and volume of pores vary dramatically under this temperature threshold. The pore morphology and distribution characteristics changed from small and sparse to large and dense. The Brunauer-Emmett-Teller (BET) surface area increased by 95%. The cumulative surface area of Barrett-Joyner-Halenda (BJH) adsorption and desorption increased by 71.7% and 72%, respectively. The pore volume of the 2-nm to 20-nm pore size increased by 63.2%. The pore volume of pore sizes greater than 20 nm increased by 191.6%. The pore variation characteristics were in line with the typing law, and the fitting result R2 ranged from 0.92201 to 0.99882.