| Songliao basin is located in Northeast China, covers the area of E119°40′～E128°24′, N42°25′～N49°23′and stretches in NNE direction, with length of 750km, width of 350km and total area of 260,000 km2。It's a Mesozoic- Cenozoic basin。The basin can be divided into seven first greade structure units,such as the central depression , the southwest uplift area, the western slope area,the northern pitching end area, the southeast uplift area, the northeast uplift area and the KAI Lu depression。The research area of Talaha-Changjiaweizi was a part of the centra depression area in Songliao basin,it covers two secondary structure units,namely the Longhupao-Daan bench and the Qijia-Gulong depression。There were Talaha and Changjiaweizi synclines in the research area,Between the two synclines there was the southern pitching end of the nose like structure of Longnan,The nose like structure of Gaoxi embed in the Changjiaweizi syncline in the eastern of the research area,In the south,it was the nose like structure of Puxi,there was a half of syncline of Longhupao-Daan bench in the weastern of the research area。The target of Putaohua Oil Layer in Talaha-Changjiaweizi was a part of the First Member of the Yaojia formation of Late Creta-ceous in age。The lithologies in this area mainly consist of gray,celadon mudstone,gray silty mudstone,pelitic siltstone,siltstone,brown siltstone with oil spot and Oil immersion,siltstone with oil concentration。They assume different thickness interbed,The contact relation between the upper and lower formation is a general disconformity。On the basic of the research for sequence stratigraphy of quartering and the character of Base-level Cycle ,three system tracts of Sequence XIV are identified in the Putaohua Oil Laye of the First Member of the Yaojia formation,they are low system tract,transgressive system tract and highstand systerm tract, Sequence XIV approximately equate to the Yaojia formation。The arenite in the research area is mainly located in the low system tract and transgressive system tract of Sequence XIV,Sedimentary Micro facies of the sandstone mainly consist of subaqueous distributary channel and channe-mouth bar。In the research area ,Delta Facies,Lacustrine Facies and Sublacustrine fan Facies have been identified,including six kinds of sedimentary subfacies and twelve kinds of sedimentary micro facies ,the delta sandstones is mostly distributed in the delta front,there is many reservoir deds in the delta front,The lithologies in the delta front mainly consist of french grey packsand,dark grey siltstone,celadon siltstone and silty mudstone。As a result of the arenite formation and the mud rock formation contact frequently,near the oil source,it mades the continuity of the sandstone poor,adding to the affecting of the fault,there may be many kinds of lithologic trap and combination trap,In addition ,multiple phases of progradation,retrogradation made sandstone overriding vertically and connectly laterally,So lithologic oil pool would be engended easily,The delta front subfacies include subaqueous distributary channel,subaqueous distributary channel gap,channe-mouth bar,distal bar,front sheet microfacies and such as,The delta front subfacis is the favorable sedimentary facies belt in this question for discussion。Turbidites discovered in Talaha synclines are the composing of material basis of sublacustrine fans,According to the describing of the Rock Core,a great deal of sublacustrine fan have been identified in the research area,It indicates that the deepwater environment in Qijia-Gulong depression has potential of lithologic oil pool formation。The reseach of sedmimentary character indicates that there are three independent sedimentary provenances,the west,the north and the east provenances。The western may be part of the Yingtai sediment system,The northern may be part of the Qiqihaer sediment system,The eastern may be part of the Beian-Nehe sediment system。The west brachy -axis sedimentary systerm was affected by the Yingtai sedimentary provenance, From the west to the east ,there was subaqueous distributary channel,subaqueous distributary channel gap,channe-mouth bar,distal bar,front sheet microfacies ;The north long axis sedimentary systerm was affected by Longhupao sedimentary provenance,from the north to the south,there was subaqueous distributary channel,subaqueous distributary channel gap,channe-mouth bar,distal bar,front sheet microfacies;The east sedimentary systerm was affected by DaqingChangyuan sedimentary provenance,from the east to the west,there was subaqueous distributary channel,subaqueous distributary channel gap,channe-mouth bar,distal bar,front sheet microfacies;The convergence region of the three sedimentary systerms was lake facies。Arenite of reservoir in the research area mainly consisted of feldspathic litharenite and lithic arkose sandstone,The diagenesis mainly comprise compaction, pressolution,cementation, metasomatism,corrosion,dissolution and clay minerals during transformation。The common clay minerals in this area are illite,chlorites,kaolinite,illite and smectite mixed lays。The clay minerals transformation is mainly in the second rapid stage。The diagenetic sequence of cement and authigenic mineral was glauconite,pyrite,crystallite calcite,adhesion calcite,secondary quartz,illite,chlorites,albitization,cement filling calcite,ankerite。The reservoir was in the A2 sub-stages of stage A of late diagenesis period;As a result of maturation of organic matter,a great deal of acidic fluid had been generated,diagenesis environment was kept in acidity at the depth of 1600-2100 meters,the corrosion,dissolution of feldspars and calcite,intergranular dissolution porosity and intragranular dissolution porosity came into being,the secondary pore zone was generated。The statistical result indicate that secondary pores at about 2100 meters is best。Below 2100 meters,due to the corrosion,dissolution of feldspars and calcite,a great deal of basic ion,such as Fe2+,Mg2+,K+,had been dissociated out,as a result of the rection of kaolinite and Fe2+,Mg2+,lots of chlorites had been generated,the content of kaolinite had been cut down,but the content of chlorites had been added to about 40%,they had a relationship of restricting each other;At the same time,due to the conversion of Smectite to illite,the content of illite was increased gradually,clay minerals during transformation caused physical property of the reservoir bad。In this process,the content of carbonates had been increased also,due to the existing of the Fe2+,Mg2+,ferrocalcite,ankerite were the commen carbonates。As a result of the increasing of the buried depth,the arenite of the reservoir had been cementated again,the late carbonates filled the early dissolution pores,which caused the reservoir porosity depressed;At the same time,secondary enlargement of feldspar was very common;Due to the great buried depth and the compaction,some mineral grain came apart at the seams。Characteristics of diagenesis indicated that diagenetic fluids experience early alkaline fluid stage, acid fluid stage and return to late alkaline fluid stage。Glauconite,pyrite,crystallite calcite,some quartze corrosion and adhesion calcite were the diagenetic sequence in alkaline environment in early age;The incursion of oil and gas made the pore fluid acidic, corrosion of feldspars was coming,kaolinite and secondary enlargement of quartze was generated;The dissolution of carbonates and feldspars ,adding to the smectite transformation,the concentration of basic ion was increasing,which made the pore fluid alkaline;The precipitation of calcite and dolomite,albitization was generated,the partial dissolution of some quartze grain even authigenic quartz were appeared。...
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