| The 3rd region is located in the southeast of Nanpu sag,Paleogene with multi-stage tectonic characteristics,has experienced many times of subsidence and uplift,formed a number of regional unconformity,with a strong imbalance and complex of the oil and gas distribution.In this paper,in order to solve these problems,selected the unconformity of Paleogene in 3rd region of Nanpu sag as the research object,focus on the unconformity of bottom of Dongying formation,based on the analysis of seismic,well logging,mud logging,core and assay data,carried out the unconformity structural characteristics and unconformity oil control research,mainly the results and understanding:?1?There are four unconformity surfaces in the Paleogene of 3rd region in Nanpu sag,with various types.Among them,truncated unconformity and over-unconformity are the main types of unconformity in the study area,and they are mostly concentrated in the middle slope of the study area.?2?The unconformity vertical structure at the bottom of the Dongying Formation can be divided into three layers:The rock above the unconformity surface,weathered clay layer and semi-weathered layer.The rock above the unconformity surface and semi-weathered layer are widely distributed in the study area,the distribution of weathered clay layers is relatively limited,showing a sporadic distribution.?3?The bottom unconformity structure layers of the Dongying Formation in the Paleogene show different characteristics in petrology,physical properties,mineralogy and elemental geochemistry.The rocks above the unconformity surface are dominated by mudstones,with few sandstones,moderate thickness,good physical properties,mostly unstable minerals and elemental content;weathered clay layers dominated by clay and argillaceous siltstones,and relatively thin thickness,mostly stable minerals and elements,poor in physical properties;the semi-weathered layer is dominated by sandstone,with less mudstone,and the thickness of a single well is relatively large,stable minerals and elements are reduced relative to the weathered clay layer and have good physical properties.?4?The combined types of the unconformity structural layers at the bottom of the Dongying Formation of the Paleogene can be divided into:Type ??capped or single channel type?,type ??“skylight”type?,type ??single channel?,type ??double channel type?,type ??capped type?,different types of combinations have different control effects on oil and gas,and can be summarized as three functions of reservoir modification,transportation and sheltering.?5?Under the control of the unconformity structure at the bottom of the Dongying Formation in the Paleogene,the oil and gas in the Es1 and the Ed3 are characterized by“more on the lower than above”,and oil and gas are mainly concentrated on the reservoirs adjacent to the unconformity surface below the unconformity surface.Show that the hydrocarbon enrichment of the first section of the Shahejie formation is higher than that of the third section of the Dongying formation. |
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