Analysis On Reservoir Characteristics And Reservoir Formation Of Wuerxun-Beier Depression In Hailar Basin

Wuerxun-Beier Depression are two large oil-rich sags,and are the main explorationtargets in Hailar Basin. The oil and gas exploration in such a complex rift basin hasundergone long term hard and tortuous experience. This paper aims at the complicatedgeological factors which restrict the oil and gas exploration in Hailar basin,employs seriesof reservoir evaluation techniques including the whole rock analysis , thin sectionidentification,intersection chart method,multi-parameter comprehensive interpretation, andso on, to analyze the petrographic characteristics of reservoirs. By using the explorationtheory of subtle reservoir and the basic principle of sequence stratigraphy, establishinghuman-computer exchange data platform and spatial velocity field, utilizing well-seismicjoint interpretation model and horizon attribute slice analysis, perspective analysis, lithologicbody depiction, visualized stochastic inversion with geophysical technologies, such asGeoprobe software, to establish isochronal sequence stratigraphic frame, regional tectonicevolution, sedimentary system and reservoir distribution, the distribution law of favorablelayers and oil and gas reservoir are gradually recognized.Four innovations of study method and technology application have been obtained.Firstly, under the direction of theory of subtle reservoir and sequence stratigraphy,exploration strategy of Hailar Basin has been changed. That is from single structuralreservoir and antithetic normal fault reservoir to lithologic-structural reservoir, finally to findlithologic reservoir. Secondly, the traditional working mode has been changed. WithDoublefox software for the first time, human-computer exchange data platform and spatialvelocity field are established, and used successfully to study sequence strata, reservoircharacteristics and reservoir formation. Prospecting effects in production and practice havebeen achieved. Thirdly, utilized successfully the leading prospect techniques, such asgeophysical analysis, visualization and stochastic inversion with Geoprobe software,tracingand characterization of interlayer geologic body are carried out,the breakthrough is madeduring exploration practice in the eastern slope of Wuerxun depression and Beizhongsub-sag of Beier depression. Fourthly, due to the particularity of reservoir in Hailar basin,multiple techniques are organically combined,a set of microscopic analysis and reservoirevaluation method of Wuerxun-Bei’er depression is established.There are four aspects of geological knowledge and results achieved in this paper,firstly, based on the establishment of sequence framework, the relationship among group,formation and member is clarified. The strata are divided into Budat Group, Tongbomiao Formation, Nantun Formation, Damoguaihe Formation, Yimin Formation, andQingyuangang Formation from below to above. Secondly, the main source rocks are darkmudstones in the layer of Tongbomiao, Dantun, and Damoguaihe formation. The oil layerare mainly distributed in base rock, Xing’anling-Tongbomiao Formation, the first, secondmember of Nantun Formation, and the second member of Damoguaihe Formation. Thesource-reservoir-cap assemblage is classified into three sets as follows: upper, middle andlower. Thirdly, the matured source rocks in main sag control hydrocarbon accumulation. Themain fracture and unconformity are the main channels for hydrocarbon migration. Faultedstructural belts are hydrocarbon enrichment zones. Reservoir types are various with multiplehydrocarbon accumulation rules. Fourthly, the small depression of the residual rift basinswill have prospecting potential with better conditions of reservoir formation. The mainexploration targets are interlayer low amplitude structure and interlayer lithologic body.This research not only has practical significance to exploration and development inHailar Basin,but also has certain effect on enrichment and perfection of oil-gas reservoirgeological theory in complex rift basin , meanwhile it has reference significance toexploration evaluation of other oil-gas fields with the similar geological conditions.