深部超临界地热资源研究进展及开发前景展望

Research progress and development prospect of deep supercritical geothermal resources

较之于传统的地热资源,超临界地热资源具有更大的开发潜力,但目前对于后者的研究尚处于初步探索阶段,在理论研究和技术实践上均面临着诸多挑战。为了实现我国的节能减排目标并为能源结构调整做出贡献,系统回顾了国际超临界地热资源钻探工程及测试过程,归纳总结了其在钻井、完井技术方面的经验和教训;进而结合国际上超临界地热资源室内实验、场地试验及数值模拟方面的研究成果和最新动态,指出了超临界地热资源开发所面临的挑战、潜在的解决方法、未来的研究方向和技术开发重点。研究结果表明:①在理论研究方面,需要弄清亚临界—超临界流体的多相流动特征、超临界水的化学特性及水岩作用机理、高温条件下岩体力学的弹塑性及其变化等重要问题;②在工程实践方面,如钻完井和测井技术在极高温和酸性流体条件下的应用、超临界条件下多场耦合模拟的程序开发工作等均面临重大挑战;③需要进行水、盐、酸性气体等多组分的超临界状态方程的理论研究,并开发相应的状态方程模块;④在场地示范工程方面,需要加强地热资源评估与勘探方法、高温钻井与测井技术、储层建造技术、地表系统等研究;⑤需要研发和提升高温超高温钻井、完井技术,研发环保及可降解钻井液等。结论认为,不久的将来,随着科技的进步,将有可能实现对超临界地热资源的商业化开发。

Compared with traditional geothermal resources,supercritical geothermal resources have greater development potential.At present,however,the research on supercritical geothermal resources is in the preliminary exploration stage,and the theoretical research and technical exploration face many challenges.In order to reach the goal of energy saving and emission reduction and make contribution to energy structural adjustment in China,this paper systematically reviews the drilling engineering and testing engineering of supercritical geothermal resources all over the world and summarizes the experience and lessons in terms of well drilling and completion technologies.Then,the challenges to the development of supercritical geothermal resources,the potential solutions,the future research direction and the key points of technical development were pointed out based on the international research achievements and latest situations in terms of laboratory experiment,field test and numerical simulation of supercritical geothermal resources.And the following research results were obtained.First,from the aspect of theoretical research,it is necessary to figure out the multiphase flow behaviors of subcritical-supercritical fluids,the chemical characteristics and water-rock reaction mechanisms of supercritical water,the elastic-plastic deformation of rock mass mechanics under high-temperature conditions and other important issues.Second,its engineering practice faces severe challenges,such as the application of drilling and logging techniques under the conditions of ultra-high temperature and acid fluid and the program development of multi-field coupling simulation under supercritical conditions.Third,it is necessary to carry out theoretical research on the supercritical state equation of multiple compositions(e.g.water,brine and acid gas)and develop the corresponding state equation module.Fourth,as for field demonstration engineering,it is necessary to strengthen the studies on geothermal resource evaluation and exploration methods,high-temperature drilling and logging techniques,reservoir construction techniques and surface systems.Fifth,it is necessary to develop and improve high and ultra-high temperature drilling and completion techniques and develop environmental and degradable drilling fluids.In conclusion,with the scientific and technological progress,the commercial development of supercritical geothermal resources may be realized in the near future.