Tight Sandstone Gas Reservoir Effectiveness And Hydrocarbon Forming Regularity Of Es4 In Jiyang Depression

In recent years,breakthroughs of cracking gas exploration have showed the deep gas exploration potential in jiyang depression,But deep sandstone reservoir densification and effective reservoir evaluation and cracking gas accumulation etc.have affected the deep oil and gas exploration in the future.On the basic of studying tight sandstone lithology,rock mineralogy,sedimentary facies of Es4 in Dongying north fault zone and Bonan sag,this article points out that the tight sandstone reservoir includes mainly the conglomeratic sandstone,grit,sandstone etc.in nearshore subaqueous fan and in fan delta sedimentary system,rock mineral composition is made up of mainly feldspar,quartz and lithic,pore structure is micropoe-fine throat,the pore is capillary-micro capillary pore;The storage space mainly includes the primary residual intergranular pore,secondary dissolution pore and fracture.The properties of reservoir are characterized by low porosity,low permeability or low porosity.Puts forward four deep reservoirs densification types which are Miscellaneous precipitation densification,strong compaction densification,cement the densification and asphalt filling densification in Jiyang depression;and analyses of the densification process of sandy conglomerate of nearshore subaqueous fan and the sandstone of fan delta facies.Establishes the porosity evolution model of wealthy miscellaneous conglomerate,and wealthy miscellaneous sandstone,poor miscellaneous conglomerate,poor miscellaneous sandstone.Quantitatively evaluate the effect of compaction,cementation,corrosion and asphalt filling on pore evolution of reservoir in densification.Through the sedimentary burial history,diagenetic evolution,hydrocarbon generation and evolution,pore evolution,etc.,puts forward the model of reservoir pore evolution about early failure evolution and dissolution transformation type,the large pores reduse through the early compaction and cementation of reservoir,only less pores rise through later dissolution.Solution transformation type mainly includes conglomeratic sandstone and sandstone in nearshore subaqueous fan,the large pores rise through later dissolution.The dissolution of poor miscellaneous conglomerate improves 11.8%of porosity,the dissolution of poor miscellaneous sandstone improves 16.5%of porosity,the dissolution increases the reservoir property of the reservoir,and the dissolution model is an important type of tight sandstone reservoir.Using the method of testing,the oil-bearing occurrence method,distribution function method and other methods,defines the lower limit of the effective reservoir porosity and permeability.The the lower limits of condensate gas reservoir porosity is 3.8%,effective permeability lower limit is 0.4×10^-3um²,the lower limits of gas reservoir porosity is 3.0%,effective permeability lower limit is 0.2×10^-3um² in the Dongying sag north-fault zone.But the lower limits of gas reservoir porosity is 4.8%,effective permeability lower limit is 0.2×10^-3um² in the Bonan sub-sag.Sedimentary microfacies,diagenetic facies and fracture is equal"three-phase"and temperature-pressure in the formation control the effective reservoir.Predicte the effective reservoir distribution fengshen 1,feng-8 of Dongying sag and the boshen 8 belt in Bonan sub-sag.Application of gas geochemical properties,identifies cracking gas of crude oil and kerogen cracking gas formation,the gas reservoir of Minfeng fault belt belongs to the cracking gas of crude oil,the gas reservoir of Lijin fault belt and Bonan subsag belongs to the natural gas kerogen pyrolysis gas in dongying sag.By means of the hydrocarbon generation evolution,reservoir densification evolution,fluid pressure changes,oil and gas gathering differentiation etc.,establishes the accumulation evolution model of tight sandstone oil cracking gas and kerogen cracking gas.Cracking gas of crude oil is early filling into reservoirs,late crude oil cracking in Minfeng region,kerogen cracking gas is early loss,late filling into a reservoir in Lijin region.In this paper,put forward the model of"temperature-phase-potential"coupling control reservoir.Sedimentary facies,diagenetic facies,cracks are equal"three-phase"matching controls the tight sandstone reservoir effectively,fluid potential not only have an effect on reservoir physical property,more important is the main dynamic factors of migration.