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

由于石油和天然气开发的经济和环境限制，对高性能模拟软件的需求非常强烈，用于利用增强型地热系统(EGS)开采低渗透干热岩层中的深层地热储层，在这些岩石中，岩石被压裂以使冷水流过并被加热发电。然而，在为EGS提供完善的压裂模拟软件方面，服务业还存在一个空白。石油地质技术公司(PGI)，一家总部位于加拿大卡尔加里的全球先进的岩土力学和岩土工程软件开发公司。为了保持行业领先地位，PGI正在寻求为EGS开发复杂的储集层和裂缝模拟工具，包括热压裂建模。与滑铁卢大学(UW)的热压裂建模专家合作，PGI将以更高的效率推动EGS复杂热压裂模型的开发。项目目标包括：(1)开发适当解决热对流的EGS的CO2冷压裂模型；(2)改进的CO2压裂模型，使用位移不连续方法处理覆盖层效应；(3)进一步改进的考虑EGS中自然裂缝的热压裂模型。项目成果将包括用于EGS的复杂的热压裂模型，该产品有望在提高热传递、应力重分布和热裂缝扩展监测的准确性方面具有巨大潜力。好处将包括更负担得起的地热能，额外的环境友好型热源，温室气体的减少，以及热提取效率的提高。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，而由EGS(与供暖系统集成)开发的较小规模的发电机在加拿大可以在环境和经济上具有吸引力。据信，拟议的研究工作将促进加拿大的地热能产业，从而有利于就业和可再生能源经济。

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.