Formation Mechanism And Prediction Of High Quality Reservoir In Lower Porosity And Permeability Reservoir

The world has entered the conventional oil and gas production stable rise andrapid development of unconventional oil and gas phase, routine to unconventionalreservoirs, promote the fast development of global unconventional oil and gasexploration and development, gradually changing the pattern of the world’s energysupply. Conventional oil and gas exploration is difficult at present, domesticunconventional oil and gas is a beneficial supplement. Daqing Oilfield Company inSongliao basin of conventional oil and gas reservoir exploration degree is higher, thegradual shift in the direction of dense oil and gas exploration.This paper, by usingpolarizing microscope, scanning electron microscopy (SEM), energy spectrum analysis,cathodoluminescence microscope, X-ray diffraction analysis, fluid inclusions,fluorescence observation and uniform temperature test, laser Raman spectroscopy,normal test method of stable isotopes, fluid-phosphate rock interaction experiment,laser confocal analysis and QEMSCAN test technology of Daqing Placanticline Fuyureservoir sandstone reservoir is studied, and the results show that:Petrological study shows that Daqing Placanticline Fuyu reservoir sandstonereservoir types are mainly feldspar lithic sandstone, followed by lithic arkose, verysmall amounts of feldspar sandstone and lithic sandstone. Filler content/authigenicmineral including mechanical infiltration of clay, overgrowth quartz and quartz, feldspar overgrowth, calcite, chlorite, anhydrite, kaolinite, and so on.From early to latediagenetic symbiotic sequence in the order: mechanical infiltration of clay, chlorite,microcrystalline calcite, overgrowth quartz/micro quartz, feldspar and calcitedissolution, dissolution, oil and gas injection, increased secondary feldspar, kaolinite,bitumen, authigenic illite, pyrite, anhydrite and calcite crystal.The reservoir in the study area with dense reservoir Ⅰ classes and densereservoir Ⅱ class is given priority to, followed by conventional reservoir. In densereservoir pore space is mainly on the microporous and holes. Reservoir space is mainlyfor primary pore, followed by secondary porosity.Main control factors of reservoirdensification for mechanical compaction, carbonate cementation and filling withasphalt. Secondary pore formation of the ancient fluid for organic acids.Objective strata during the diagenetic process has experienced three periods of lateearly mid alkaline, acid and alkaline ancient fluid. Acidic ancient fluid temperature is80-110℃, with fresh water.Inclusions GOI analysis shows that oil and gas fillingstrength is low, in addition to the apricot tectonic zone belongs to the ancient westreservoir, other tectonic zone is only the ancient oil and gas transport express way.Thealkaline fluids of the ancient temperature is115-130℃, the formation of coarse graincalcite mainly related with the organic acid decarboxylation, and carry shell sourcesource strontium strontium and sea mixed signal. Organic acid filling is secondary poreformation of trigger mechanism, feldspar is the main contributor, secondary poreformation temperature is beneficial to the dissolution of feldspar.At the sametemperature conditions, the degree of the dissolution of plagioclase is higher thanpotassium feldspar.Is advantageous to the secondary pore formation temperaturewindow for "100℃-160℃.On the longitudinal, the tectonic zone development1-2secondary poresdevelopment zone, the development of the biggest is buried deeply,2400m, the light is1450m. South in the F1layer, in addition to Portugal and AoNa tectonic zone is Ⅱfavorable zone, other tectonic area for Ⅰ classes and class Ⅱ favorable area; In F2 layer, sashi, sal figure, apricot, west, north high platform, Portugal and the PortugueseⅠ class areas favorable for southern tectonic zone, north west, Portugal and thePortuguese lamadian, Portugal Ⅱ class areas favorable for southern tectonic zone,almond and taiping chariot and AoNa tectonic zone for Ⅰ classes and class Ⅱfavorable area;In F3layer, almond, high platform and taiping tuen areas favorable forⅠ class, lamadian, sashi, sal figure, almond, high in the west, taiping chariot andadvantageous area Ⅱ for Portugal’s west tectonic zone, Portugal’s north south,Portugal and AoNa tectonic zone for Ⅰ areas favorable for classes and class Ⅱcommon.Innovation point of this article is mainly in two aspects:(1) using the QEMSCANanalysis technology, combined with polarizing microscope, carbon and oxygen isotopeand inclusion analysis to determine the diagenetic evolution, find out the oil and gasinjection after the change of reservoir minerals in sandstone and coarse grain calcitelate causes, reveals the reasons of reservoir densification, proposed acid ancient Fuyureservoir fluid is given priority to with fresh water, some existing enrichment or retainwater features.(2) through the fluid flow and rock interaction, combined with the actualgeological conditions, find out the effects of organic acids on fossil secondary change,reveals the organic acid under the condition of the formation mechanism of secondarypores in sandstone reservoir.