Petrological Characteristics And Diagenesis Of Silurian Xiaoheba Formation In Fuling Area

Silurian has favorable conditions,with good potential for oil and gas exploration in Fuling area.However,there are imperfect study on the sandstone reservoir diagenesis and physical characteristics in Fuling area.Therefore,based on a large collection,collation and analysis of previous studies,by outcrop measurement and sample collection and analysis,using ordinary thin section,thin sections casting,scanning electron microscopy,X-ray diffraction and vitrinite reflectance and other analytical testing methods,systematic study of the Silurian Xiaoheba group petrological characteristics and diagenesis in Fuling area,combined with the physical property tests to study the effects of diagenesis on reservoir properties,made the following understanding:The rock types of Silurian Xiaoheba group is feldspar and quartz siltstones,followed by quartz siltstone and lithic quartz siltstones in Fuling area.The highest of content of detrital is quartz mineral,followed by feldspar.Clastic particle size predominantly silt,inferior race,rounded corners-rounded second main support particles,cement-based approach to the pore cementation.The main sedimentary rock cuttings cuttings,the main mineral component is mica,a small amount of local biological debris.Argillaceous cementation cementation and carbonate cementation based.The calculated compositional maturity of 7.62 for moderate compositional maturity.The main pore types of corrosion holes.Size normal probability distribution curves represent the characteristics of the two-stage,second overall jump sorted,fine particle size,suspended second overall poor sorting,large particle size difference;Fuling Silurian Xiaoheba group has low porosity and permeability characteristics,average porosity of 2.67%and average permeability of 0.40×10^-3?m²,since the reservoir of micro fractures,poor correlation between porosity and permeability;Fuling Silurian Xiaoheba main groups of diagenesis including compaction,cementation,dissolution,fracturing and the like.Wherein the mechanical compaction,cementation calcite,silica cementation,cementation muddy destructive diagenesis,partially rigid particle breakage and cracking microfracture,resorption of constructive diagenesis.Characterized by authigenic mineral,clay mineral analysis,analysis of maturity of organic matter,pore type,known Fuling Silurian sandstone diagenesis Xiaoheba majority has been reached in diagenetic B stage.The study and analysis of diagenetic authigenic minerals generated Fuling Silurian rocks Xiaoheba composition sequence to be divided,the main area of diagenetic sequence:mechanical compaction-clay minerals recrystallized-No early calcite cementation iron-mature organic-no iron calcite dissolution-dissolution of feldspar-quartz overgrowth-iron filling calcite secondary intergranular pore-fracture effect.Compaction and cementation are the main factors reducing the reservoir properties,calculated,initial porosity of about 46.76%,the compaction rate of about68.67%,cementation rate is about 9.32%,compaction of Fuling area Xiaoheba group greater impact;dissolution and rupture role is to improve the area Xiaoheba formation reservoir property's main diagenesis,limited improvement of reservoir fracture breaking role.