Development of a thermal fracturing model for cold CO2 injection in enhanced geothermal systems

由于对石油和天然气开发的经济和环境限制，存在对高性能模拟软件的强烈需求，所述高性能模拟软件用于在具有增强型地热系统（EGS）的低渗透性的干热岩石中的深部地热储层的增产，其中岩石被压裂以使冷水流过并被加热以用于发电。然而，在服务行业中存在一个缺口，以提供复杂的压裂模拟软件来促进EGS。石油地质技术公司(PGI)是一家全球领先的地质力学和岩土工程软件开发公司，总部位于加拿大卡尔加里。为了保持行业领先地位，PGI正在寻求为EGS开发复杂的储层和裂缝模拟工具，包括热压裂建模。 PGI与滑铁卢大学（UW）的热压裂建模专家合作，将以更高的效率推进EGS复杂热压裂模型的开发。项目目标包括：（1）开发了EGS的冷CO2压裂模型，适当解决了热对流问题;（2）改进的CO2压裂模型，使用位移不连续方法解决了上覆岩层效应;（3）进一步改进的热压裂模型，考虑了EGS中的天然裂缝。 项目成果将包括一个复杂的EGS热断裂模型，该产品有望提高传热、应力再分布和热断裂扩展监测的准确性。好处将包括更实惠的地热能，额外的环保热源，减少温室气体，提高热提取效率。通过利用可回收的二氧化碳，该技术将减少供水困难的偏远地区的用水量，并且从EGS开发的较小规模发电机（与加热系统集成）在加拿大具有环境和经济吸引力。拟议的研究工作被认为有利于就业和可再生能源经济，促进加拿大的地热能源产业。

Due to the economic and environmental constraints on oil and gas development, there is strong demand for high performance simulation software for stimulation of deep geothermal reservoir in hot dry rock of low permeability with enhanced geothermal systems (EGS), where rock is fractured for cold water to flow through and to be heated for electricity generation. However, there is a gap in service industry to provide sophisticated fracturing simulation software to facilitate EGS. Petro-Geotech Inc. (PGI), a global progressive geomechanics and geotechnical engineering software developing company headquartered in Calgary, Canada. To keep the lead in the industry, PGI is looking to develop sophisticated reservoir and fracture simulation tools for EGS, incorporating thermal fracturing modeling. Partnered with thermal fracture modeling experts at the University of Waterloo (UW), PGI will advance development of sophisticated thermal fracturing models for EGS with higher efficiency. Project objectives include: (1) development of a cold CO2 fracturing model for EGS with heat convection properly addressed; (2) an improved CO2 fracturing model that addresses the overburden effect using the displacement discontinuity method; (3) a further improved thermal fracturing model that considers natural fractures in EGS. Project results will include a sophisticated thermal fracturing model for EGS, a product that is expected to have great potential to increase the accuracy in heat transfer, stress redistribution and thermal fracture propagation monitoring. Benefits will include more affordable geothermal energy, an additional environmental-friendly heat source, reduction in greenhouse gas, and increased heat extraction efficiency. By utilizing recyclable CO2, the technology will reduce water usage in remote areas where water supplies are difficult, and a smaller scale power generator developed from the EGS (integrated with a heating system) can be both environmentally and economically attractive in Canada. The proposed research works are believed to benefit the employment and renewable energy economy by boosting the geothermal energy industry in Canada.