页岩气开发机理、模拟及优化研究

Shale gas, as an unconventional gas resource, has a tremendous potential for future energy growth. However, the development of shale gas in our country has just started. The fundamental mechanisms of shale gas development and methodologies of shale gas flow simulation have not been established. The prominent characteristics of shale is its low porosity and low permeability, thus the development of shale gas is more difficult than the conventional natural gas, and the fluid migration mechanisms of shale gas involved in the shale gas development are much more complicated..The proposed project will study the adsorption, diffusion, and flow mechanisms of shale gas in the multi-pore media composed of pores and fractures with different scales, to understand its migration law in the subsurface. New computational models for multi-scale, multi-pore medium will be established, in which the comprehensive migration mechanism of shale gas and the effect of its coupling with geomechanics will be fully considered. A set of numerical simulator for shale gas development will be developed, which can be used for productivity prediction and optimization. In one word, the proposed research will provide a scientific foundation for the development of shale gas in China.

页岩气作为一种新型的非常规天然气资源，开发潜力巨大。但我国页岩气的开发刚刚起步，在适合我国具体情况的页岩气开发机理及流动模拟研究方面尚未形成一套完整有效的理论和方法。页岩显著特点是低孔隙度、低渗透率，页岩气在开发过程中涉及的流体运移机理比常规天然气复杂得多，开发难度更大。.本项目将开展页岩气在不同尺度的孔隙和裂缝所组成的多重介质中的吸附、扩散和流动机理研究，把握其地下运移的规律；建立新的页岩气计算模型，构建多尺度、多重介质方程，综合考虑页岩气运移机理以及与岩石力学之间耦合作用;开发一套具有自主知识产权的页岩气开采数值模拟器;运用数值模拟对国内外典型页岩气区块开采进行产能预测与开发方案的优化，从而为我国页岩气开发方案的确定提供科学依据。

本课题在2013年至2016年期间进行了大量的文献调研，在已有的工作基础上对页岩气的流动机理和模型进行了全面总结，并据此建立了新的机理模型；在已有的油藏岩芯实验室基础上搭建了页岩气机理分析测试平台，自行设计了页岩气高温高压等温吸附仪、渗透率测试仪等装置及用于校准页岩实验的标准测试样品。针对页岩的超低渗透性，推导建立了考虑滑脱效应和吸附扩散的新的页岩气渗流机理模型，并分析其对产量的影响；通过建立类组分模型和数值模拟，定量分析了分别以吸附态和自由态储存于基质和孔隙/裂缝中的页岩气的组成成分，提高了对页岩气产量来源的机理认识；建立和完善了具有自主产权的页岩气开发的数值模拟器UNCONG，模拟器较好地解决了页岩气模型中裂缝系统、Knudsen扩散和岩石变形的模拟；在UNCONG的基础上建立了基于集合的历史拟合和优化流程，在实际页岩气井的测试中，该历史拟合方法可以到达较高的准确度。..课题培养了5名博士，发表了20多篇SCI论文，部分研究成果形成了软件。课题实施期间，研究人员积极进行学术交流，参与了大量国内外页岩气相关的会议，并邀请了多名国内外专家来做学术报告。本课题对认识页岩气开发机理、帮助我国在页岩气领域追赶国际先进水平做出了贡献。