Rock property change and temperature distribution near blasting holes in carbon dioxide blasting reservoir treatment

Abstract:

The traditional geothermal well structure is not suitable for carbon dioxide blasting technology to build hot dry rock reservoir； Thus， this paper further explores a new well structure and related technology suitable for carbon dioxide blasting technology. With regard to the actual drilling conditions in the horizontal well section （blasting hole） of the new well structure， rock mechanics experiments and thermal-fluid-solid three-field coupling numerical simulation were conducted to study the variation law of physical and mechanical properties and reservoir temperature distribution characteristics of hot dry rock reservoirs near horizontal well sections （blasting hole） after drilling. The results show that the thermal stress produced by cooling of drilling fluid is the main cause for the change of reservoir rock properties and occurrence of the thermal damage zone. The regional temperature distribution exhibits the characteristics of “rapid cooling zone-steady cooling zone-uncooling zone” in reservoir near the borehole during cooling. The initial reservoir temperature and the cooling time have major influence on temperature distribution in the rapid cooling zone and on the thermal damage zone. This study can provide more accurate theoretical guidance for carbon dioxide blasting fractured hot dry rock reservoir.