Predicting Direct And Indirect Uses Of Geothermal Energy In Major Oilfields Of China
80% of China’s energy needs are addressed through the use of fossil fuels. To overcome this, there is a growing focus on the use of renewable sources of energy mainly wind and solar. As a result, the existing geothermal resources in the dying oilfields of China get ignored. There are numerous oilfields which are no longer economically productive and have entered a stage of more than 95% water cut. The hot water associated with such oilfields can be utilized directly or indirectly as a geothermal resource. The geothermal gradient of various oilfields located on eastern, north eastern and central sedimentary basins of China namely DQ (Heilongjiang province), XN (Sichuan basin), CQ (Ordos basin), HN (Dongpu depressions) and HB,SL,LH (all located in offshore Bohai basin) are reviewed. The graph of reservoir temperature versus depth is utilized in obtaining the geothermal temperature gradient for these fields. Based on the geothermal temperature gradient the Lindal diagram is plotted. Lindal diagram indicates the direct application at low to intermediate temperature ranges (20-150 oC) and indirect application at high temperature ranges (150-300 oC) of geothermal resources.. The direct application of geothermal resource is in agriculture,, and agro-based industries, while, the indirect application is for steam or electricity generation (70-149 oC). In addition, the heat loss of water when reached at surface is calculated based on the assumption of real field case. The heat loss indicates that the surface temperature is different as compared to temperature of the water in the reservoir resource of the dead oil field. Thus, this drop in water temperature will shift both direct application and indirect application of geothermal resources on Lindal diagram. Therefore, Lindal diagram with change in temperatures are also displayed in this paper. In short this paper will provide a basic information of direct and indirect application of geothermal reservoirs associated with above mentioned dead oil fields of China.
Index Terms- China Geothermal, Lindal Diagram, Oilfields