鄂尔多斯盆地三叠系延长组页岩气形成条件及有利发育区预测

页岩气勘探开发始于美国,并且取得较好的地质效果和经济效益。页岩气是一种非常规天然气,以吸附或游离状态为主要存在方式,表现为典型的“原地”成藏模式,其成藏受泥页岩厚度、分布、有机地球化学特征、孔隙度和渗透率条件、裂缝发育程度、盖层条件等的综合控制。鄂尔多斯盆地三叠系延长组泥页岩分布广泛,并且泥页岩厚度较大、有机碳含量较高、热演化适中、气测显示活跃、页岩中裂缝发育,页岩气资源潜力较大。初步研究表明鄂尔多斯盆地南部地区是三叠系延长组页岩气发育的有利区域,其中定边-华池-富县的“L”型区域是最有利发育区,向外围泥页岩气的潜力逐渐变小。

Preliminary Analysis of Shale Gas Resource Potential and Favorable Areas in Ordos Basin

The exploration of shale gas was firstly put into practice in USA. Shale gas is a kind of unconventional natural gas, which mainly accumulates in adsorbed and free phases. Shale gas is characterized by insitu accumulation, and controlled by the thickness and distribution, organic geochemical characteristics, porosity and permeability, fracture development and seal conditions of the shale. The shale of Yanchang Formation is widely distributed in Ordos Basin, and is characterized by big thickness, high TOC, moderate thermal evolution, popping gas survey, and well developed fractures. The preliminary research shows that the south Ordos Basin is the favorable area of the shale gas development of Triassic Yanchang Formation, and the “L-type” area of Dingbian|Huachi|Fuxian is the most favorable area for the shale gas development. The shale gas potential decreases gradually outwards to the surrounding area.