Fabric characteristics and oil accumulation laws of shales in fine-grained areas of faulted lacustrine basin:a case of Paleogene in Huanghua Depression
In order to clarify the microscopic fabric characteristics and oil accumulation laws of shales in fine-grained areas of faulted lacustrine basin,based on the core data,logging data and oil testing data of three sets of shale successions in the second member of Kongdian Formation(Kong 2 for short),the third member and the first member of Shahejie Formation(Sha 3 and Sha 1 for short)of the Paleogene in Huanghua Depression,mineral analysis-field emission scanning electron microscope,argon ion polishing-field emission scanning electron microscope,focused ion beam-field emission scanning electron microscope etc.were used to characterize shale samples at multiple scales and dimensions in detail.The characteristics of shale minerals,organic matter,pores and shale oil occurrence were systematically analyzed from the microscopic and quantitative points of view,to reveal the accumulation and enrichment laws,and enrichment model of shale oil.The results show that in the microscopic view,complex types of shales are composed by multiple types of minerals mix and stack in laminae.The reservoir space in shale can be divided into nine types in three categories,including inorganic pore,organic pore and microfracture.Inorganic pores account for more than 85%on average,and pores with diameters less than 50 nm take up the majority of the reservoir space.Microscopically,there are three types of organic matter,synsedimentary organic matter,intergrown and differentiated organic matter,and migration and filling organic matter.Based on the characteristics,distribution and spatial interrelationship of four elements,including minerals,organic matter,reservoir space and hydrocarbons in shale strata,a"four-element coupling"reservoir accumulation and enrichment law is proposed,and three types of shale oil accumulation and enrichment models are sorted out.Under the guidance of these models,several horizontal wells have tapped high oil production in the Kong 2 Member in Cangdong Sag,and high-quality shale oil blocks have realized economically viable development at the current oil prices.Meanwhile,shale oil exploration has made major breakthrough in Sha 3 Member and lower submember of Sha 1 Member in Qikou Sag.All these show broad exploration prospects of Paleogene shale oil in Huanghua Depression.
shale oilthe second member of Kongdian Formationthe third member of Shahejie Formationthe first member of Shahejie FormationHuanghua Depressionfabric characteristicsoil accumulation laws
万方数据
维普
