Geological Identification And Oil-bearing Evaluation Of The Fourth Member Of Shahejie Formation In The West Slope Of Damintun Sag

Daming Tun sag is one of the three major oil generating depressions in Liaohe Oilfield.The reservoirs are widely distributed and rich in oil reserves,which is the main battlefield for exploration in Liaohe Oilfield.The exploration of the fourth member of the Shahejie Formation of the west slope in the Paleogene started late,and the scale of the reserves discovered was relatively low.There are three main problems,one is that the exploration and evaluation of the reservoir is limited to a homogeneous fine sandstone reservoir,which is dominated by drainage in the four section of the sand,and the reservoir is divided into single and gravel thickness.The large and horizontal contrast is poor,and there is a lack of subdivision and fine contrast of sand and gravel.The second is fan delta facies sedimentary system,fan lithology is complex,reservoir types are diverse,well logging is difficult to recognize,the third is the development of high-quality source rocks in the Sha4 section,and the favorable reservoir forming conditions.However,due to the lack of knowledge about the oil-bearing nature of the reservoirs,the exploration results of the reservoirs are poor.For better evaluation of Sha four member reservoir in west slope of Damin Tun depression,according to the specific oil geological characteristics and the current exploration status in the study area,this paper uses geological logging technology,core scanning technology,thin slice identification technology,gas logging technology and geochemical logging technology to evaluate the reservoir lithology identification and oil-bearing evaluation of the Sha4 section.Study in depth.It is of great significance to establish the standard of the period division and the detailed comparison scheme of the gravel rock mass in the next step.It is of great significance to describe the plane,the longitudinal distribution characteristics and the oil-bearing distribution law of the effective reservoir in the deployment area.Therefore,this paper collects and collects the data of 50 wells in the west slope of the Damen depression,identifying and analyzing the lithology of the Sha4 section,and redescribing the lithology.The subject has completed the core description and core scanning of 22 wells long 138.45 m,completed 19 wells and 904 pieces of lithology,completed 155 samples of 20 wells,and 100 samples of 4 wells were analyzed for lithology identification and lithologic profile reduction of the core and 19 wells in 22 wells.On the basis of this,the geological stratification of 12 wells has been modified,and the four reservoir of sand is reclassified and 7 sets of sand layers are divided,and 8 reservoir contrast maps are made.At the same time,the logging data of the exploration well and key well in the original research area are analyzed.Combining the geochemical analysis results of 1402 samples in 24 wells,the oil-bearing property of the four reservoir is interpreted and evaluated,and the standard of the oil bearing limit is given.On this basis,8 reservoir sections are completed,and the oiliness of the Sha4 section is vertically and horizontally.The distribution characteristics are studied,and the favorable oil-bearing areas are redefined to provide favorable support for finding more potential reservoirs.Based on the identification of reservoir lithology and oil-bearing evaluation of the reservoir in the Sha4 section of the study area,it is found that the distribution area of Pinganpu sand body is larger and the Anfu Tun is small,and the lithology is multiphase and multi-source,from Pinganpu to Anfu Tuen from the Archaean boundary to the Mesozoic,and the four segments of Pinganpu sand are divided into 7 sand bodies.The four section of Anfu Tun Sha is divided into 4 sand body development periods.The reservoir belongs to the sedimentary system of "near shore fan fan delta",and four sand reservoirs in the sand are distributed in block shape,controlled by oil source and fault,and the oil property of the reservoir gradually becomes worse from East to west.Through this study,the reservoir lithology and oil-bearing property of the Sha4 section in the west slope of the damun depression are further understood,and the next step is to compare the four sections of the sand reservoir,to divide the sedimentary facies and to the sedimentary period,to study the reservoir control factors and distribution rules,to carry out the favorable exploration targets,to formulate the exploration scheme and to deepen the potential of the reservoir exploration.Expand the exploration area,provide sufficient theoretical basis,and further promote the exploration process in this area.