Microstructural Characteristics of Damaged Hot Dry Rock Flow Network Stimulated by Cryogenic Liquid Nitrogen Shock

ACS Omega, Journal Year: 2025, Volume and Issue: 10(1), P. 1261 - 1278

Published: Jan. 2, 2025

Hot dry rock (HDR) geothermal development faces challenges due to the difficulty of stimulating fluid flow and heat-exchange fracture channels within deep, low-porosity, low-permeability reservoirs. A liquid nitrogen cyclic cold shock method was proposed, using as a fracturing fluid. The large temperature difference between hot induces thermal stress, forming complex pore-fracture network. In this study, HDR samples at various temperatures were subjected 5 cycles shock. Pore-fracture structures damaged cores tested by low-field nuclear magnetic resonance X-ray microscopy. Results showed temperature-dependent changes in porosity: 200 300 °C, small-size pores rose, with maximum porosities 3.13% 3.37%; 400–500 large-size reaching 4.59% 12.76%. Different pore types exhibited distinct responses: mesopores are most sensitive shock, micropores responded early damage stage, macropores only under high-temperature differences multiple cycles. Multifractal analysis revealed increased heterogeneity concentration distribution escalation. slice porosity, fractal box dimension, probability entropy demonstrated exponential growth. indicate that is main controlling factor HDR, can also contribute continuous development. There high correlation parameters multifractal parameters, allowing reflect more structure quantitatively.

Language: Английский

Overestimation of pore volume in high-TOC shales by low-temperature nitrogen adsorption: Phenomenon and cause analysis

Chemical Engineering Journal, Journal Year: 2025, Volume and Issue: unknown, P. 159695 - 159695

Published: Jan. 1, 2025

Language: Английский