Study On The Characteristics Of Shale Reservoir In Paleogene System In Dongying Sag

Along with the worldwide oil and gas production is declining,unconventional oil and gas has become the main alternative sources,and the shale gas content is so huge that shale gas research is vital to alleviate the crisis of resources.Shale gas reservoirs with low porosity and low permeability,pore structure and reservoir minerals complex,multi-facies type and other characteristics,Research with the shale reservoir potential of hydrocarbon generation,accmulation,reservoir brittle,etc of which based on petrographic unitsplays an important role on the development of shale gas.Dongying sag has the best quality source rocks in Jiyang sag and even in Bohai Bay Basin.Currently,industrial flows have been gained in the shale development section in many exploration wells,showing the Dongying sag has good prospects for shale gas exploration and development.This article has mainly researched petrology characteristics,shale rock characteristics,source rock characteristics,reservoir characteristics,microscopic pore structure,diagenesis,the brittleness of the shale research,the advantages of petrographic evaluation and several other aspects of the researches with the meathods of core observation,thin sections,scanning electron microscope?SEM?,argon particle polishing,X-ray diffraction analysis,high-pressure mercury injection,low temperature nitrogen adsorption,carbon dioxide adsorption,rock pyrolysis analysis,mechanical analysis of rock and other methods of shale research.Dongying sag shale petrofacies finally be divided into six types that islamellar argillaceous limestone,massive argillaceous limestone,lamellar lime mudstone,massive mudstone,massive silty mudstone and laminated silty mudstone;mineral content changes range great in which the highest content is carbonate minerals,felsic mineral clay mineral content is higher,the clay minerals mainly illite,mixed-layer illite-based;In Dongying sag,the mean of TOC in Upper Section of S4 is 3.72%,Ro mean of 0.81%,the mean of TOC in S3 is 4.43%,Ro mean of 0.91%,whicn shows high abundance of organic matter,good organic matter types?mainly of?and??,organic maturity in the low maturity-high mature stage,the body is in the mature stage,the main oil source of which has the the basic geological conditions of shale oil and gas generation.Reservoir space is mainly include structural fractures,bedding joints,abnormal pressure joints,mineral contraction joints and organic evolution hole,intragranular dissolvtion pore,intergranular pore,intercrystalline pores.Physical property test results showed that average porosity is 4.87%,permeability mean of 0.656mD;Meathods of high-pressure mercury intrusion porosimetry,nitrogen adsorption,carbon dioxide adsorption,show that the mean ofpore volume were 0.024cm³/g,0.0058cm³/g,0.0018cm³/g;mean specific surface area of 1.736m²/g,4.289m²/g,5.04m²/g,the mercury porosity is 5.594%.Shale pore size obtained mainly diatributed in the range of 10nm and 100?m,3-5nm,within 0.42-0.9nm.And the main pore types are mainly to open cylindrical hole,parallel plate which is open pore,also contain the ink bottle type such as irregular hole.And organic matter content,quartz mineral,clay mineral content control on the shale porosity development;after methane adsorption get shale gas adsorption capacity is0.0724mmol/g,and it is mainly due to the organic content,mineral components,micropore and mesopore;The whole of the shale rock up stage A₂,and are developed dissolution,cementation,metasomatism,compaction,recrystallization,clay mineral transformation function of diagenesis;By mechanics experiment shows that the high brittleness of the shale.Finally,according to four indicators that TOC,porosity,reservoir space,brittleness,evaluating the hydrocarbon generation,reservoir,fracturing in three aspects.Choose the TOC as the main evaluation parameters,divided the six major lithofacies into class?,?,?reservoirs.Wherein the laminar lime mudstoneand laminated argillaceous limestone is generative hydrocarbon facies that belonging to class?reservoir;massive argillaceous limestone and massive mud phase belong to class?reservoir;bedded silty mudstone and massive silty mudstone belong to class ? reservoir.