Research On Sedimentary Microfacies Of Saertu Oil Layer In Block Ta 35 Of Longhupao Oilfield

In recent years,a number of wells in the Sapu oil layer in the Long 12-Ta 35 area of Longhupao Oilfield have obtained industrial oil flow,showing good potential for increasing reserves.However,the sedimentary characteristics and reservoir distribution of the Sartu oil layer in the Ta 35 block are still unclear,and there is no overall comprehensive geological analysis and no fine sedimentary microfacies research.This restricts the understanding and further development of oil distribution in the Sartu oil layer in the Ta 35 block.Therefore,it is urgent to conduct a complete and systematic study of sedimentary microfacies in this area.Aiming at the Sartu oil layer,this paper establishes a fine stratigraphic framework for the target layer in the study area by combining with the relevant data of mud logging,well logging and seismic.Sedimentary source analysis and sedimentary facies type analysis were also carried out.Using seismic facies and seismic inversion reservoir prediction results,the distribution law of sandstone groups in the study area and the thickness of each layer of sand bodies were obtained.Combined with the seismic inversion results,the distribution of the sedimentary microfacies is finely described.The sedimentary evolution characteristics of the study area were analyzed,and the sedimentary model of the study area was established.The results obtained in the research of this paper are as follows: According to the stratigraphic development characteristics of the study area,the Sartu oil layer is divided into three oil layer groups and 31 sub-layers: Sa I,Sa II and Sa III;Based on the basic theory of sedimentary petrology,combined with logging,logging and other data,the sedimentary facies type of the Sartu oil layer is analyzed as delta facies,and two sub-facies of outer delta front sub-facies and shallow lake sub-facies are used as Mainly,5 sedimentary microfacies of underwater distributary channel,main sheet sand,non-main sheet sand,underwater inter-distributary bay and mouth bar are developed;Using seismic facies and multiple characteristic parameters such as heavy minerals,mudstone color,sandstone maturity,clay minerals,etc.,comprehensive research,combined with the paleogeomorphology and sand-ground ratio characteristics of the study area,multidimensional comprehensive research and judgment,and the provenance analysis of the target layer in the study area.It is determined that the provenance of the target layer mainly comes from the northwest direction.Using seismic waveform inversion to invert each oil layer to predict the thickness of the sand body,the sandstone thickness of the Sa II oil layer group is the largest,and the distribution trend is thick in the southeast and thin in the northwest;The plane distribution of sedimentary facies of the Sartu oil layer shows that the sedimentary period of the Sartu oil layer was dominated by sheet sand deposits in the outer front of the delta,and the littoral-shallow lacustrine facies developed in the southeast of the study area.In the Sa I depositional period,the outer delta front and the shallow lake subfacies developed in turn from north to south;in the Sa II depositional period,the outer delta front subfacies mainly developed,mainly sheet sand deposits;in the Sa I depositional period,the lake basin scale Expansion,from north to south,the outer front of the delta and the shallow lake subfacies developed in turn,and the area of the shallow lake reached the maximum deposition state of the Sartu oil layer.According to the research knowledge,the sedimentary microfacies map of the sandstone formation and main sublayer of the Sartu oil layer in the Ta 35 block was drawn,and the sedimentary evolution law was analyzed and summarized,which provided a new understanding of the geological characteristics of the Sartu oil layer in the Ta 35 block of the Longhupao oilfield.certain basis.