Electricity generation and heating potential from enhanced geothermal system in Songliao Basin, China: Different reservoir stimulation strategies for tight rock and naturally fractured formations

Daqing City in Northern Songliao Basin (China) requires huge amounts of electric power and thermal energy for oil processing and resident support each year. We used actual geological and logging data of deep well YS-2 in Daqing oilfield to investigate electricity generation and heating potential from enhanced geothermal systems in tight rock and naturally fractured formations (3850-4500 m) using different reservoir stimulation methods. We then proposed optimized hydraulic fracturing and heat extraction strategies for each formation. Results indicate that the Yingcheng formation is suitable for the development of HDR (hot dry rock) resources in this region. Heat output in the stimulated naturally fractured formation is obviously higher than that in the tight rock formation. The development of HDR resources in the naturally fractured formation should be prioritized. In middle-low temperature (about 160 °C), tight rock formation still has great potential for heating supply, but the structure has poor capacity for electricity generation because of the low appropriate injection rate resulting from low reservoir temperature. However, when a high temperature reservoir is selected, electricity generation is feasible from tight formation by using gel-proppant hydraulic fracturing combined with horizontal well technology.