武隆地区五峰组—龙马溪组优质浅层常压页岩储层发育特征及含气性影响因素

Development characteristics and gas-bearing factors of high-quality shallow ordinary-pressure shale reservoirs in Wufeng-Longmaxi Formation in Wulong Area

武隆区块浅层常压页岩气藏已被证实为四川盆地渝东南地区重要的页岩气勘探开发潜力目标。通过X射线衍射、有机碳测试、物性测试、扫描电镜观测和薄片观测等测试手段,对武隆区块F-2井五峰组与龙马溪组页岩不同层段代表性样品的储层发育特征开展系统分析,探究储层含气性及其影响因素,并讨论优质浅层常压页岩气储层控制因素与机理的特殊性。结果表明:五峰组至龙马溪组底部、下部层段有机质含量较高(3.72%~5.70%),脆性矿物比例较高(>50%),孔隙度相对较高(2.90%~6.25%),含气性均显示较好(>4.0 cc/g),是优质浅层常压储层段。储层含气性影响因素复杂,有机质含量、脆性矿物比例和孔隙度均与含气性呈正相关关系,高黏土矿物含量导致含气性下降。优质储层可以分为五峰组、龙马溪组底部和龙马溪组下部3个层段,但3段优质储层的高含气性控制因素与机理存在差异。探究优质浅层常压页岩气储层含气性影响因素与特殊性,可以为进一步提高对浅层常压优质页岩储层地质特征认识、指导勘探开发提供科学依据。

The shallow ordinary-pressure shale gas reservoir in Wulong Block has been confirmed as an important potential target for shale gas exploration and development in southeast Chongqing Area,Sichuan Basin.By methods of X-ray diffraction,organic carbon test,physical property test,scanning electron microscope observation,thin section observation and other test methods,this paper systematically analyzes the reservoir development characteristics of representative samples of different shale intervals in Wufeng-Longmaxi Formation of well F-2 in Wulong Block,explores the gas-bearing property of the reservoir and its influencing factors,and discusses the particularity of the control factors and mechanisms of high-quality shallow atmospheric shale gas reservoirs.The results show that:The organic matter content is higher(3.72%~5.70%),the ratio of brittle minerals is higher(>50%),the porosity is higher(2.90%~6.25%),and the gas-bearing property is better(>4.0 cc/g),is a high-quality shallow atmospheric reservoir.The organic matter content,brittle mineral ratio and porosity are relatively high,which is a high-quality shallow ordinary-pressure reservoir.The influencing factors of the gas bearing capacity of the reservoir are complex.The content of organic matter,the proportion of brittle minerals and porosity are all positively correlated with the gas bearing capacity.The high content of clay minerals leads to the decrease of the gas bearing capacity.The high-quality reservoir interval can be divided into three layers:Wufeng Formation,the bottom of Longmaxi Formation,and the lower part of Longmaxi Formation,but there are differences in the control factors and mechanisms of high gas content in the three high-quality reservoirs.Exploring the influencing factors and particularity of the gas-bearing property of high-quality shallow atmospheric shale gas reservoirs can provide scientific basis for further improving the understanding of the geological characteristics of high-quality shallow atmospheric shale gas reservoirs and guiding exploration and development.