Prof. D. N. Singh

DR. FAAKIRAH RASHID MIR

Ph.D.
Indian Institute of Technology Bombay, Powai, India mirfaqra333.fm@gmail.com

GEOTHERMAL HEAT EXTRACTION FROM ABANDONED OIL AND GAS WELLS

Heat and mass transfer characteristics (viz., permeability, thermal conductivity, thermal diffusivity, specific heat capacity and heat transfer coefficient) of the reservoir rocks predominantly control the heat-extraction efficiency of geothermal systems. In this context, researchers have mostly conducted investigations on igneous rocks. However, in the past two decades, due to an increased focus on geothermal energy extraction from the Abandoned Oil and Gas Wells (AOGWs), understanding the characteristics of the porous sedimentary oil reservoir rocks (PSOR), which are essentially porous fractured matrix exposed to the corresponding in situ reservoir conditions (viz., elevated temperature and pressure), has become essential. Incidentally, the AOGWs contain an enormous source of subsurface reservoir data, in the form of temperature, pressure, saturation of hydrocarbon(s) and formation water (viz., brine), mineralogy, porosity, permeability and pore-size distribution, which can be employed to develop models to quantify: the yield of heat (YOH), defined as geothermal heat extraction efficiency, and the duration of heat extraction (DOHE). Incidentally, both YOH and DOHE depend upon the heat transfer mechanism(s) and changes that occur in the reservoir due to injection of the working-fluid (water in the present study). This study highlights the importance of considering contemporary issues that need to be addressed for evaluating the performance of the AOGWs as a sustainable energy resource. With this in view, efforts have been made to (i) optimize an appropriate geothermal energy system GTES for heat extraction, (ii) study the interaction between low-temperature working fluid and the reservoir formation, and (iii) establish the influence of various operational parameters related to reservoir characteristics and working fluid on geothermal heat extraction from AOGWs.