华北地区北部中—上元古界泥页岩储层特征及页岩气资源潜力

中国页岩气资源丰富,已取得了南方下古生界海相页岩气和中生界陆相页岩气勘探开发的突破,但对于华北地区分布广泛的中—上元古界古老泥页岩,前人对其烃源岩特征开展了较多研究,作为页岩储层研究还是空白。对天津蓟县地区中—上元古界串岭沟组、洪水庄组、下马岭组泥页岩,通过全岩及黏土矿物X射线衍射分析、地球化学分析、压汞、氮气和二氧化碳气体吸附分析,结合环境扫描电镜(ESEM)及场发射扫描电镜(FESEM)观察,进行了储层黏土矿物组成、TOC含量、成熟度、孔隙类型特征及评价研究,结果显示:样品矿物成分以石英和黏土矿物为主,其中石英含量20.3%~52.3%,黏土矿物含量38.4%~54.1%,TOC含量从0.008%~3.440%不等,Ro值范围为1.44%~3.01%,样品整体孔隙较发育,孔隙类型主要包括粒间孔及粒间溶孔、有机质边缘孔、粒内孔及粒内溶孔、黏土矿物晶间孔等,3个岩组泥页岩对比分析认为洪水庄组页岩储层最好,其次是下马岭组和串岭沟组。

Characteristics and evaluation of the Meso-Neoproterozoic shale gas reservoir in the northern North China

China is rich in shale gas resources. A breakthrough has been made in the exploration and development of Lower Paleozoic marine shale gas and Mesozoic continental shale gas in the south of China. In terms of the Meso-Neoproterozoic paleo-shale widely distributed in North China, many previous studies are focused on the characteristics of source rocks, but not on shale reservoirs. Through whole rock and clay mineral X-ray diffraction analysis, geochemical analysis, mercury penetration, nitrogen (N₂) and carbon dioxide (CO₂) adsorption analysis in combination with ESEM and FESEM observations, relevant evaluation and research was performed on clay mineral composition, TOC content, maturity, and pore type characteristics of reservoirs for the shale in Meso-Neoproterozoic Chuanlinggou Formation, Hongshuizhuang Formation and Xiamaling Formation, Jixian, Tianjin,. The results indicate that mineral compositions of the sample mainly consist of quartz and clay minerals, of which the content is 20.3-52.3% and 38.4-54.1% respectively, TOC content is 0.008-3.44%, and Ro values are ranged in 1.44-3.01%. The pores are relatively developed in these samples, which mainly include inter-grain and dissolution pores, organic marginal pores, intra-grain and dissolution pores, inter-crystal pores in clay minerals and so on. According to a comparative analysis on three sets of shale, it is considered that the shale reservoirs are most favorable in Hongshuizhuang Formation, followed by Xia maling Formation and Chuanlinggou Formation.