Research On Accumulation Evolution Characteristics Of Key Faulted Basin In Southern Songliao Basin

In this paper, we analysis the faulted basin structure in the base, with hydrocarbon sourcerocks evaluation, hydrocarbon generation potential analysis and oil and gas source contrastand numerical simulation as the main working; aim at Zhangwu faulted basin and Changtufaulted basin, we using methods of that, Drilling and geophysical exploration methodscombined, Oil and gas geochemical test and evaluation methods combined, to analysis thesefaulted basins.Research thinks, because of restriction of the basal differences and basal fracturedistribution, faulted basins in southern Songliao basin show characteristics of fault depressionsuperimposed type, in under the control of the boundary faults of NE and NW and NNWtrend, it developed the three different tectonic division：western faulted basin Group, easternfaulted basin Group and southern faulted basin Group. It developed two big sedimentarysystems in cretaceous，lakes and fan delta. Lakes system developed half deep lake-deep lakephase and shallow lake sub-facies, some faulted basins developed sublacustrine fan phase, fandelta system developed fan delta front phase, former fan delta phase; in sedimentary period ofJiufotang formation and Shahai formation, half deep lake-deep lake facies and fan delta frontfacies combined in different periods, form the sandstone mudstone layer of mutualcombination. The exhibition of half deep lake-deep lake phase and the material sources ofsupplying control distribution of the quality of the hydrocarbon source rock. Overall,Jiufotang formation which Water into the type of sedimentary sequences is primarily sequenceis the main source rocks, expressed as the characteristics of large thickness, high abundance,good types and low mature–mature, good-better oil source rocks are distributed in each2ndhollow center of faulted basins, Organic carbon abundance is more than3.0%, types are type Ito type II1, Ro value is from0.7~1.2%. Dark mudstone of Shahai formation has the poor typeof organic matter, maturity is relatively low or immature, it is the second source rocks in thesefaulted basins. Single well and faulted basin numerical simulation reveals that The mainperiod of hydrocarbon generation of source rocks in Jiufotang formation of the southern faulted basin group (Zhangwu faulted basin for example) is in middle and late of Fuxinformation. Source rocks of Jiufotang formation in the eastern faulted basin group generatedhydrocarbon in the late of Fuxin formation, they generated hydrocarbon again in LateCretaceous, because of further depth.Comparison of the geochemical characteristics of the oil source, mature crude oil ismainly from the source rocks of lower Jiufotang formation. There are lithologic reservoir thatis reservoir characteristics and mode of “self-generated self-reservoir, the followinggenerates the above reservoir” and construct–lithology reservoir that is reservoircharacteristics and mode of“the following generated above the reservoir, lateral migration,close accumulation”.