Analysis Of Lithologic Oil Deposit Formation Condition And Exploration Technology Of Jimusar Sag Of Junggar Basin

The exploration of Jimusar sag in Eastern Junggar Basin was begun in the50s of the lastcentury, the permian system Wutonggou group is an important exploration stratum, which hasnever obtained a substantive breakthrough mainly due to oil deposit formation conditions,depositional system characteristics and research lags of trap identification technology. Thepermian system Chinese parasol ditch group is the fan-type delta depositional system. Thesystematic research on oil gas enrichment rules in the fan-type delta depositional system andtrap identification technology has great significance on the exploration breakthrough ofJimusaer sag.The research on depositional system characteristics, mainly based on the principle ofsequence stratigraphy, classifies stratum sequence combining with an individual well andseismic reflection amplitude, frequency and geometric characteristics. On this basis,90-degreeof phase rotation and sparse pulse inversion shall be carried out on broadband seismic data toobtain sand-shale data volume and then extract the amplitude attribute and the waveimpedance attribute in the framework of lowstand system tracts, water transgression systemtracts and highstand system tracts so as to conduct the depositional system forecast anddetermine the evolutionary process and distribution characteristics of depositional systems.The research on oil deposit formation conditions mainly determines the advantageousmigration pathway of oil and gas through the research on hydrocarbon generation potential ofhydrocarbon source rock in Jimusaer area, the hydrocarbon generation critical moment of oildeposit and paleotectonic map of the permian system Chinese parasol ditch group at criticalmoment in order to further evaluate the hydrocarbon accumulation conditions of potentialtraps and provide the drilling proposals.This paper mainly achieves the following results:1) The permian system Chinese parasolditch group is divided into two sequences, three system tracts; the low system track is theactive period of basin structure, where the material provenance supply is adequate and theglutenite is distributed contiguously; in the water transgression system tracts, the materialprovenance supply is diminished, and along the fault zone, a series of fan-type delta grouphave been formed, between which the bays have been developed and the trap formationconditions are well formed; the water range of highstand system tract is located in highstandstable period and the sedimentary scope is limited in Jimusaer No.7wells area;2) Theprovenance system in permian system Chinese parasol ditch group is controlled by the activityintensity of fault system. The fault system at the southeast wing of Jimusaer sag is active and becomes the main supply area of material provenance, while the fault activity intensity at theeastern wing of Jimusaer sag is more gentle and becomes the secondary supply area of thematerial provenance;3) The oil gas in permian system Chinese parasol ditch group in Jimusaersag is mainly from the hydrocarbon source rock of permian system flat spring group, and thehydrocarbon generation and expulsion peak period is the end of the Cretaceous period,specifying the structural nose zone at east-west direction in the southern Jimusar sag is theadvantageous migration zone of oil gas combining with the top boundary paleotectonic map ofpermian system Chinese parasol ditch group at the end of Cretaceous is the preferentialbreakthrough area for exploration;4) Preferentially selected3traps in the oil gas advantageousmigration channels, deployed Jimusar No.171well, Jimusar No.19well and Jimusar No.7well areas, evaluated industrial oil flow obtained from wells and submitted over50milliontons of controlled reserves combining with the reservoir prediction and fracture identificationresults;5) The three dimensional amplitude preservation and broadband processing of JimusarNo.17well was completed, the bandwidth was broaden from9-50H to10-31Hz with broadenbandwidth21Hz, performance of the marked matching of synthetic seismogram was wellwhich is proved to be amplitude preservation and broadband data;6) The system summed upthe series of lithologic deposit exploration technologies, mainly including broadbandprocessing technology,90-degree phase rotation and sparse pulse inversion technologies anddescribed the seismic attribute research ideas within the framework of the system tracts. Theabove technologies can solve the identification problems of fan-type delta depositionalsystems.