页岩气勘探开发中的几个地质问题

A few geological issues in shale gas exploration and development

以常压页岩气藏勘探开发中的几个地质问题为研究对象,探索进行了常压页岩气藏分类,着重分析泥页岩的有机碳含量变化、热演化程度与孔隙度的关系。在此基础上,进一步研究含气量与这几个地质因素相互间的制约及其与初始产量的关系,同时对照国内外典型页岩气藏实例,探讨不同压力梯度页岩气运移对气藏初始产量的控制作用。明确指出,盆(内)缘过渡型常压页岩气藏和盆外残留型常压页岩气藏,页岩气的运移补充能量存在差异。虽然存在散失,但由于盆内页岩分布面积大,页岩气的运移补充充足,盆(内)缘过渡型常压气藏具有较高的初始产量和较好的商业效益;盆外残留型常压气藏,页岩分布面积有限,运移补充不充分,属于偏低常压,初始产量较低。要实现商业开发,还需要大力攻关增产与降本技术。

Based on several geological problems in the exploration and development of the normal pressure shale gas reservoir, its classification is explored. For that, the relation between the change of organic carbon content, the degree of thermal evolution and porosity in shale are analyzed. On this basis, the relation between gas content and these geological factors, and between the gas content and initial production are further studied. At the same time, compared with the typical shale gas reservoirs at home and abroad, the controlling effect of shale gas migration with different pressure gradients on the initial production of gas reservoirs is discussed. It is clearly pointed out that there are differences in the energy supply for shale gas migration between transitional normal pressure shale gas reservoir at the margin of(or in)the basin and residual normal pressure shale gas reservoir outside the basin. Although there exists loss, because of the large distribution area of shale in the basin and the sufficient migration and replenishment of shale gas, the transitional normal pressure gas reservoirs at the margin of(or in)the basin have higher initial production and better commercial benefit. While for the residual normal pressure gas reservoirs outside the basin, as they have limited shale distribution area and insufficient migration replenishment, they belong to low pressure reservoir and have low initial production. In order to realize the commercial development, it is necessary to make more breakthroughs in the technologies of increasing production and reducing cost.