Study On Hydrocarbon Accumulation Law Of Syncline Area In Sanzhao Depression

After nearly 40 years development of Putaohua reservoir in Sanzhao depression of Songliao basin,and with the main block have been used,the remaining unused areas are mainly located in synclinal area of dqjression,but its oil-water distribution is very complex,which caused the expansion of development area and the well pattern of evaluation area more difficult.It is necessary to carry out the systematic study of reservoir law.In this paper,based on the oil and gas accumulation dynamics and sequence stratigraphy theory,we studied the main control factors,such as Putaohua reservoir fault characteristics,the oil reservoir type,sedimentary microfacies and the oil-water distribution rule,which provided guidance for rolling development in synclinal area.Putaohua reservoir fault has small scale and large density,south and north trend,the formation of density belt in plane,“flower shaped” combination characteristics in profile,and its formation is controlled by the basement fault,later strike-slip and oblique extension,and so on;Putanhua reservoir fault consists of three sets of fault system on the vertical,including oil source faults which are the multi-phase inheritance activity faults density zone with theboundary faults.Dense well network of sedimentary microfacies reveals Putaohua reservoir inSongliao basin is the northern source under the control of the river shallow-water delta sedimentary,because of the lake level fluctuation,the underwater distributary channel microfacies is contimums,intensive which extends farther,and constitutes the main reservoir of oil and gas reservoir;At the same time,Putaohxia reservoir has the sedimentary sequence evolution the first reliction-later progression” on the vertical,and the central PI5 layer which is the largest period of reliction,forming the major oil and gas reservoir.The reservoir profile shows trap type of synclinal area are mainly complex fault block,fault-micro amplitude and fault-lithologic.The oil and gas distribution is controlled by a single trap,and lateral seal hydrocarbon column height is 40 m on average.The oil and water distribution of syncline area control by the central structural ridge,including north and south district.The supply of oil source from northern synclinal area is weak,and the oil and water control by structure.The supply of oil source from central synclinal area is strong,and the oil and water distribution control by oil source faults(fault intensive band).Based on the main control factors,we can propose four factors which control Putaohua reservoir: ? the oil source and migration path control the range of the oil accumulation and distribution;? the reverse oil source faults of the nose structure and fault intensive band is the favorable area of tile reservoir;? the intersection of fault intensive band is the favorable position of oil accumulation;? the oil ismainly located in the intersection of oil source faults and good lateral connectivity of distributary channel sand body.Eventually established two kinds of accumulaton model for the syncline area and the surrounding area of Putaohua reservoir: the oil source faults of source area match the vertical migration model of channel sand body;and the ancient structure of outside source match from the vertical to lateral migration model of channel sand body.Under the guidance of the accumulation model we can predict three types of 65 favorable traps,and provide the next exploration and development for the syncline of Putaohua reservoir in Songliao basin.