Abstract
Assessment of available geothermal resources in the deep oil field is important to the synergy exploitation of oil and geothermal resources. A revised volumetric approach is proposed in this work for evaluating deep geothermal potential in an active oil field by integrating a 3D geological model into a hydrothermal (HT)-coupled numerical model. Based on the analysis of the geological data and geothermal conditions, a 3D geological model is established with respect to the study area, which is discretized into grids or elements represented in the geological model. An HT-coupled numerical model was applied based on the static geological model to approximate the natural-state model of the geothermal reservoir, where the thermal distribution information can be extracted. Then the geothermal resource in each small grid element is calculated using a volumetric method, and the overall geothermal resource of the reservoirs can be obtained by making an integration over each element of the geological model. A further parametric study is carried out to investigate the influence of oil and gas saturations on the overall heat resources. The 3D geological model can provide detailed information on the reservoir volume, while the HT natural-state numerical model addressed the temperature distribution in the reservoir by taking into account complex geological structures and contrast heterogeneity. Therefore, integrating the 3D geological modeling and HT numerical model into the geothermal resource assessment improved its accuracy and helped to identify the distribution map of the available geothermal resources, which indicate optimal locations for further development and utilization of the geothermal resources. The Caofeidian new town Jidong oil field serves as an example to depict the calculation workflow. The simulation results demonstrate in the Caofeidian new town geothermal reservoir that the total amount of geothermal resources, using the proposed calculation method, is found to be 1.23e+18 J, and the total geothermal fluid volume is 8.97e+8 m3. Moreover, this approach clearly identifies the regions with the highest potential for geothermal resources. We believe this approach provides an alternative method for geothermal potential assessment in oil fields, which can be also applied globally.
Highlights
Due to the increasing market demand for energy, the shortage of conventional fossil fuels, and the concerns regarding the environmental aspects, the exploitation of renewable energy has become the focus of research and keeps gaining attention in recent years
The total geothermal fluid volume estimated is 8.97e+8 m3, which is nearly half compared with the traditional methods, which can be explained by two facts: 1) the total volume of the Ng1–Ng3 formations estimated in the proposed method is 35% less than the traditional method, and 2) the porosity is overestimated in the traditional method
In order to account for the influence of the oil and gas saturations on the total geothermal resources of this area, revised volumetric method calibration is carried out by assessing the geothermal resources with respect to water, oil, and gas
Summary
Due to the increasing market demand for energy, the shortage of conventional fossil fuels, and the concerns regarding the environmental aspects, the exploitation of renewable energy has become the focus of research and keeps gaining attention in recent years. Geothermal energy is a stable, environmentally friendly, and cheap renewable energy source, showing a promising perspective as a conventional fuel substitute. Such energy transition promotes geothermal energy development in oil fields. Geothermal resource assessment is a standard practice adopted by the geothermal industry in evaluating a geothermal system and its potential generation capacity It plays a crucial role in quantifying the amount of available thermal energy for geothermal exploration, providing essential information for further decision making, economical evaluation, and so on. It serves as a framework for developing a geothermal prospect in a sustainable manner. The success of a geothermal development project relies on a robust resource assessment methodology that can predict, with a lower level of uncertainty, the magnitude of energy that is stored and can be extracted and utilized from a given geothermal reservoir
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