Research On Oil And Gas Reservoir Of Upper Paleozoic In Dongpu Depression

Oil and gas exploration in upper Paleozoic of dongpu depression shows good oil and gas display,but no breakthrough has been made.Aiming at this problem,the upper Paleozoic reservoir in dongpu depression is studied in this paper.Through core observation,identification of common slice,identification of casting thin slice,scanning electron microscopy,cathodoluminescence,mercury intrusion,X-ray diffraction and well logging data,etc.,combined with the determination of the inclusions in the paleotemperature,vitrinite reflectance(Ro)and the maximum pyrolysis peak temperature(Tmax),the petrological characteristics,reservoir characteristics and diagenesis of the Upper Paleozoic reservoir sandstones in the Dongpu Depression are analyzed.And this paper analyzed the dominant characteristics of the strata that see the better oil and gas display to provide a reference for the analysis of the characteristics of the unknown formation in the study area.The rock types of the Upper Paleozoic reservoir sandstones in the Dongpu Depression are mainly lithic quartz sandstone,lithic feldspar sandstone and lithic sandstone.The Fanxian bulge area and the central uplift area are mainly lithic feldspathic sandstone and lithic sandstone.The western slope area is mainly feldspar lithic sandstone and lithic quartz sandstone.The southern erosion area is mainly lithic quartz sandstone and feldspar sandstone.The sorting property is medium,and the rounding is sub-edge-sub-circular;in general,the content of debris is higher than that of feldspar;the interstitial materials are mainly matrix,cement and clay mineral,which have great influence on the reservoir.The reservoir space of the study area includes primary pores,secondary pores and fractures,mainly secondary pores;the correlation between porosity and permeability is good,the average porosity is 6.09%,and the average permeability is 0.22×10-3 ?m2.On the whole,the reservoir belongs to tight reservoir with ultra-low porosity and ultra-low permeability.The reservoir physical properties in the central uplift area of the Dongpu Depression and the Shiqianfeng Formation and the Upper and Lower Shihezi Formations in the western slope area and the Upper and Lower Shihezi Formations and the Shanxi Formation in the southern erosion area are better,so there may be better oil and gas display.The diagenesis of reservoirs in the study area includes compaction,pressure dissolution,cementation,metasomatism and dissolution.The compaction is stronger,and the dissolution in the central uplift and western slope area is stronger than in other zones,which is beneficial to the development of reservoirs.The diagenesis stages of the reservoir were divided by the paleotemperature,vitrinite reflectance,maximum pyrolysis peak temperature and montmorillonite content in the Illite/montmorillonite mixed layer.The study area is the Mesodiagenetic stages A-B as a whole.Through the analysis of the log curve GR and AC wavelet transform,it is found that the GR value of strata with good oil and gas display is generally medium-low value,and the shape of the curve includes the jagged box,and the chromatogram shows spectral superposition of multi-scale values,with the scale values mainly being 51,94 and 158.AC value of this section is generally low,and spectral superposition of multi-scale values appears in chromatogram,the scale values are mainly 40,90 and 131.Based on this,the identification and prediction of Pushen 8 well shows that the reservoir in 5180-5190m and 5240-5254m are suspect oil and gas reserviors.