Research On Filling Mechanisms And Oil Gas Geological Conditions In Yalu River Basin

Yalu River Basin is a typical multicycle and multiplex basin,which is potentially rich in oil and gas resources.Owing to the low exploration level,lack geological data and poor seismic data quality,the geological research on Changbai depression is very little.According to collect the previous literature,various sample analyzing results and previous research,guided by oil-gas exploration method of composite superimposed basin,this paper established a comprehensive geophysical inversion method suitable for the kind of basin like Changbai depression on the basis of identifying the physical characteristics of density,magnetism and resistivity and density interfaces.According to the inversion profile and plane distribution characteristics of comprehensive geophysical interpretation,this paper made research on structure,distribution features of volcanic rocks and sedimentary rocks,filling mechanism,oil gas geological condition and oil-gas favorable prediction.(1)On the basis of geophysical property and its interface characteristic conclusion,this paper makes gravity,magnetism and resisvtivity processing and analyzing,potential field conversion,anomalous field qualitative analysis and geological attribute identification,so as to obtain the information of fault distribution and field source property distribution.Aimed at this research,this paper provides methods of gravity-magnetic-seismic combination inversion,gravity and magnetic interface inversion and gravity-magnetic-resistivity-seismic comprehensive interpretation to solve the geological problems of Changbai depression,such as fault features,basement structure,structural units,distribution characteristics of sedimentary formation and volcanic rocks.(2)Faults are well developed in Changbai depression with different orientation and scale.Most6 of faults are in NE and NE direction,and a few in NW direction.There are 4 faults controlling the geotectonic unit characteristics in Changbai depression.The structural evolution can be divided into 5 phases of movement.(3)The structural characteristic of Changbai depression is two uplifts and a depression in the middle,which are Laoling uplift,Yingkou-Kuandian uplift and Changbai depression.Controlled by Changbai northern margin fault and NE faults,Changbai depression is characterized by belts in S-N and blocks in E-W.(4)The formations of Z-?-O,C-P and J are all developed in the depression.Z-?-O is widely distributed with large thickness and C-P is limited remained in deep of the depression with thin thickness.There are 8 sedimentary systems developed from Proterozoic to Cenozoic era.(5)According to the analysis of parameter well,drilling well and geology materials,there are three sets of major source rocks,showing the characters of many strata,large thickness,high abundance and various types.The sets of source rocks are already bled off hydrocarbon in big mass.It provides the material condition of hydrocarbon accumulation.Reservoirs are well developed from Sinian to Mesozoic,including different types of marine,continental and volcanic deposit.There are 6 sets of regional caps,which provide several sets of good source-reservoir-caprock association.(6)Based on the former study,comprehensive evaluation of Changbai depression is concluded and pointed out 7 oil-gas prospect areas.