Research On Petroleum Geologic From Upper Jurassic Series To Lower Cretaceous Series Of The Suibin Depression In Sanjiang Basin

Sanjiang basin locates the east of Heilongjiang Province.Its geotectonic position locates atthe joint region where central Asia and Mongolia structural domain and the littoral Pacific Oceanstructural domain connect,is one of the petroliferous basin based on continenatal facies and withthe help of marine and marine-terrigenous facies of mesozoic.Because of the particularity of itstectonic setting and depositional feature,Sanjiang basin plays an important role in Mesozoicstrata research.This paper based on the results of previous studies,we study on Suibin depressionin Sanjiang Basin of the petroleum geological features on the outcrop profile,drilling data,logging data, seismic data,observed by microscope,sample analysis and test,combined withorganic geochemistry, thin section identification and other effective analysis method.Firstly,we study on the sedimentary features of main stratigraphic.Indentify5kinds ofsedimentary facies such as lacustrine facies,sublacustrine fan facies,delta facies,marinefacies,alluvial fan facies,and13subfacies and23microfacies.Middle-Late Jurassic，in regionalstudies happened marine transgression,the seawater from north to south,developed DongrongFormation and Suibin Formation`s marine deposit,the stratum northern thick, southern thin. Atthe early stage of Early Cretaceous,seawater began to quit,developed delta facies andshore-shallow lacustrine facies strata,center of the sedimentation and subsidence are in the westby south of regional studies.At the Middle Early Cretaceous,seawater completelywithdraw,developed Muling`s Lacustrine deposit, center of the sedimentation and subsidence arein the west by south of regional studies.Secondly,we study on the source rocks,reservoir and cap rocks in the regional studies.Theresults shows that regional studies developed two sets of good source rocks-ChengziheFormation and Muling Formation.The organic matter abundance of Chengzihe Formation`ssource rocks is good-middle,organic matter type of Chengzihe Formation`s source rocks ishumic-sapropel humic(Ⅱ2-Ⅲ),the evolution level of most source rocks is in the postmature-high stage;The organic matter abundance of Muling Formation`s source rocks is middle, organicmatter type of Muling Formation`s source rocks is humic (Ⅲ),the evolution level of most sourcerocks is in the maturity-high maturation stage,hydrocarbon generating ability is good,beneficialto gas.The reservoirs is mainly distributed in Chengzihe Formation and MulingFormation,reservoir types is based on the fan-daelta underwater distributaries sand body,andunderwater fan is the secondary. The main types of clastic is feldspar and lithic, quartzcomponent is low, the pore types are mainly primary intergranular pore, secondary intergranularpore and intraparticle pore.The digenetic stage of reservoirs of Chengzihe Formation have beenin stage B of middle–late digenetic stage,reservoirs of Muling Formation have been in middlediagenetic stage.Reservoir sandstone`s porosity and permeability of Chengzihe Formation is verylow,Muling Formation is batter than Chengzihe Formatin,the reservoir of regional studies isbad;The mainly types of cap rocks in regional studies is k1ch and k1m`s mudstone,localdeveloped tuff cap.Mudstone of regional studies have the following characteristics:distribution iswide,lateral continuity is good,porosity is low,and capillary force is high.Tuff cap’s sealingcapability is stong. The westen`s cap rocks is better than easten.Finally,analysis and summary on the source-reservoir-cap assemblage of regional studies,recognizes the following three types:the first type is self-generating and self-preserving reservoir,the second type is source rocks below and reservoirs in the upper,the third type is reservoirsbelow and source rocks in the upper.