| This paper focus on MiCangShan structures and front areas in North Sichuan Basin,by comparing the reservoirs of Sinian Dengying Fm which locate at Gaomo area in Central Sichuan Basin and Weiyuan area in Southwestern Sichuan Basin to investigate petrology characteristics,sedimentary facies,reservoir space types and growth situation,property characteristics,diagenesis,and analyze the formation and preservation mechanism of high quality reservoirs in deep to ultra-deep superimposed Sichuan Basin.The results showed as follow:The Dengying Formation in the northern margin of the Sichuan Basin is divided into open platform and restricted platform,Which is mainly restricted platform to phase.The open platform is located in the third section of the Fucheng Dengying Formation.Tidal-flats,algae debris banks,oolitic banks and lagoons developed in the restricted platform.There could be many subtidal-intertidal-supratidal cycles in the vertical sections.The rock types of Dengying Formation in the Micangshan area in the northern part of the Sichuan Basin are mainly composed of complex and diverse microbiological rocks.They are mainly grape,karst,foam,Stone,granulite,dendrites and lamellar rocks,of which clumps,grapes and layers of stone-based,followed by foam cotton and stone-shaped stone.The fourth section of Dengying Formation is the dense muddy dolomite with the development of mudly dolomite ground of undertide,which develops Microbial dolomite locally(mainly the top).The microbial carbonate reservoirs of the Dengying Formation in the northern margin of the Sichuan Basin are mainly distributed in the second and fourth sections of the Dengying Formation.The types of reservoirs are summarized by two major categories and four subcategories.Among them,the two categories are: crevice-type reservoir space type and pore-type reservoir space type,four sub-categories:(1)karst holes(including cave,dissolved);(2)Karst holes(Including cave,hole);(3)dissolution cracks(including cracks and cracks);(4)intercrystalline denudation pore(including sand,clot particles between the pores).The combination of the main reservoir spaces in different regions and different regions is also different.The porosity of the fourth stage of Mashen 1 is 1.5-4.6%,the average is 3.3%,the permeability(0.011-0.684)× 10-3?m2,the average is 0.248 × 10-3?m2;the porosity of the four sections of the Fucheng section Dengying Formation is 0.36-2.76% 1.27%,permeability(0.03-0.164)× 10-3?m2,average 0.192 × 10-3?m2;the porosity of the second stage of Tianxing 1 is 1.71%-4.76%,the average is 3.065%,the permeability is(0.0016-0.0129)× 10-3 ?m2,mainly distributed in(0.001-0.01)x 10-3?m2,and the average value is 0.0055 × 10-3?m2..Based on the diagenetic evolution of the Ma Shen 1 well of Dengying Fm as the main body of the study,the sequence of diagenetic evolution in the study area is as follows: muddy sediments ? grain hardening / microbial muding ? sedimentary karstification / dolomitization / Pyrite mineralization / light and heavy crystallization?(structural uplift)-surface karst / fresh water silicification / mechanical rupture? compaction,pressure dissolving / recrystallization ? burial period dissolution(hydrothermal)/ filling ? compaction effect ?(Mikang Shan uplift Dengying group denudation)-organic acid dissolution silicification / karstification / rupture ?filling effect..The formation and preservation mechanism of the high quality reservoirs of the Sinian Dengying Formation in the Micangshan area of the northern Sichuan Basin mainly include:(1)the microbial rock structure and quasi-synchronic karst formation in the sedimentary period constitute the basis for the development of high quality reservoirs;(3)High-quality fractured-type reservoirs provide a favorable channel for hydrocarbon filling;(4)The corrosive release of the shade group is The damaging effect of the reservoir on the reservoir. |
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