Improving characterization and modelling of the rock-proppant interaction in hydraulic fractures for deep-earth geo-resource extraction

加拿大能源监管机构预测，加拿大天然气产量将在未来20年内增长到每天6.06亿立方米。生产将主要来自地表以下2-3公里的致密和低渗透性岩层中的天然气储量。大量的支撑剂（主要是压裂砂）被放置到由水力压裂产生的裂缝中，以增加裂缝导流能力并增强从致密地层的长期烃采收。油井增产作业的经验已经证明，在高压缩应力下岩石-支撑剂的机械相互作用显著影响裂缝导流能力，从而影响气体生产率。然而，由于现有的实验室测试和预测模型的局限性，支撑剂和岩石之间的复杂相互作用过于简化，因此缺乏裂缝导流能力在井生产寿命期间如何演变的全面和定量表征。在复杂的岩石-支撑剂系统中，许多重要的影响因素尚未完全捕获，例如岩石断裂形貌、支撑剂尺寸和支撑剂蠕变到岩石面中的压痕。这些缺点已经显著地损害了我们正确地预测支撑剂在岩石裂缝中的行为的能力，导致用于水力压裂的支撑剂的不适当选择。在我的研究活动的最新进展已经确定了需要严格的模型裂缝之间的支撑剂破碎裂缝导流能力令人满意的预测。为此，我们已经开发了一个数值破碎模型，成功地模拟在高压应力下的颗粒破碎。为这项发现补助金提出的研究计划将建立在我们现有的成功基础上，并进一步推进资源开采裂缝中岩石-支撑剂相互作用的表征和建模。这一目标将通过在先进的实验室地质材料表征、地质力学测试以及数值和分析建模等相互关联的研究任务方面对HQP进行培训来实现。研究成果将提供和促进新的知识和工具，以提高开采效率，这对加拿大天然气工业的可持续发展至关重要。将开发支撑剂和岩石的表征技术以及水力-力学行为的预测模型，以便更好地将支撑剂用于深层地球资源回收的水力压裂，同时尽量减少与支撑剂开采和运输有关的环境影响。与现有行业和学术合作伙伴的密切合作将确保研究成果的快速传播，并促进天然气开发项目的优化机会。HQP将配备加拿大自然资源部门非常需要的基本技能。

The Canada Energy Regulator predicts Canadian natural gas production to grow to 606 million cubic metres per day over the next two decades. The production will be mainly from the natural gas reserves trapped in tight and low-permeability rock formations 2-3 km below surface. Massive amounts of proppants, mostly frac sand, are placed into fractures created by hydraulic fracturing to increase the fracture conductivity and enhance the long-term hydrocarbon recovery from tight formations. Experiences from well stimulation operations have already demonstrated that the rock-proppant mechanical interaction under high compressive stress significantly influences fracture conductivity and, thus, gas productivity. However, there is a lack of comprehensive and quantitative characterization of how fracture conductivity evolves during well production life, due to the limitations in existing laboratory tests and predictive models where complex interaction between proppants and rock is over-simplified. Many important impact factors have not yet been fully captured in the complex rock-proppant systems, such as rock fracture topography, proppant size, and proppant creep indentation into rock faces. These shortcomings have significantly impaired our ability to correctly predict proppant behaviours in rock fractures, resulting in the inappropriate selection of proppants for hydraulic fracturing. Recent progress in my research activities has identified the need to rigorously model proppant crushing between fractures for satisfactory prediction of fracture conductivity. For this, we have developed a numerical breakage model to successfully simulate grain breakage at high compressive stress. The research program proposed for this Discovery Grant will build on our existing successes and further advance the characterization and modelling of the rock-proppant interaction in fractures for resource extraction. This goal will be achieved through training HQP in interlinked research tasks with advanced laboratory geo-materials characterization, geomechanical testing, and numerical and analytical modelling. The research outcomes will deliver and promote new knowledge and tools for improving the extraction efficiency that is crucial to the sustainable development of the Canadian natural gas industry. Characterization techniques of proppants and rock and predictive models of hydraulic-mechanical behaviours will be developed to better apply proppants in hydraulic fracturing for deep earth resource recovery while minimizing environmental impacts associated with proppant mining and transportation. Close collaboration with existing industry and academic partners will ensure rapid dissemination of research outcomes and facilitate optimization opportunities in natural gas development projects. HQP will be equipped with essential skills that are highly desirable in the Canadian natural resource sector.