STUDY ON THE EFFICIENCY OF GEOTHERMAL HEAT EXCHANGERS IN ABANDONED OIL AND GAS WELLBORES: A SIMULATION APPROACH

Abstract

The world requires more and more energy every day. While traditional sources of energy are near exhaustion, renewables like geothermal energy provide immense promise. Geothermal energy is the heat generated deep within the earth's core and can be extracted from the crust with abandoned oil and gas wellbores. Water is sent down the wellbore, where it absorbs heat and travels back to the surface, which is later turned to steam to produce power. Geothermal energy extraction leaves a lot to be desired. The efficiency of the current systems isn’t desirable. Of the two available technologies, CLGS (Closed-Loop Geothermal System) and OLGS (Open-Loop Geothermal System), CLGS provides an opportunity to retrofit oil and gas wells, which makes them feasible in terms of cost and accessibility. The studies that have been conducted so far indicate that water is the better heat transfer fluid overall. To enhance the efficiency of the CLGS, an understanding of the entire wellbore system must be gained. A simulation approach provides a detailed analysis of all the sections of the geothermal system. The results reveal significant heat losses from the hot fluid after reaching the surface. Installation of insulation improves performance drastically. Changing the materials shows further performance improvements. But different materials have different drawbacks. Insulation thickness also plays a significant role in heat retention and changes the flow properties. Studying all of the parameters will result in an efficient geothermal system that can be utilized in abandoned wellbores to provide more energy to the world.