Research On Sedimentary Microfacies Of Sha3Formation Of Block Wen10in Dongpu Depression

Wen10block is located in the north of Wen Liu structural belt of the central uplift zone in Dongpu Depression. The oil-bearing series of Sha3petroleum reservoir in the area is the third section of Paleogene Shahejie Formation. It is formed by complex block tectogene which is lithology-structure oil pool.After a long period of water injection, this block has entered the high water cut period, oil and water distribution is complex, the remaining oil exhibition cloth law is not clear. The reservoir micro facies sandbodies type, geometry size characteristics and distribution is the foundation to analyse the injection-production patterns nets and recognize the regularity of oil-water movements, so we need to study on reservoir sedimentary microfacies and characteristics again. This has the important practical significances on finding out the remaining oil distribution and mining potential oil to improve oil recovery ratio.In this paper, the principle of sequence stratigraphy is applied, and combined with core, logging, logging and seismic data, to study the sedimentary microfacies of Wen10oil field ES3, to identify the plane and the vertical evolution of the distribution of sedimentary facies and microfacies and the depositional model in this area, the study can provide the important geological basis for the exploration and development in this area.Based on the core observation and logging data interpretation, to combine the three-dimensional seismic data, small layers are re-classified and correlated, and the small layer system, controlled by high-resolution sequence, is established. Guidance on the rock stratigraphy and high-resolution sequence stratigraphy, applying of point, line, surface three-dimensional integrated approach, and the small layers of about116wells are fine classified and correlated.On the basis of the previous studies, through the core observation and the analysis of sedimentation background and sedimentary characteristics, the study shows that ES3reservoir are primarily a delta front subfacies and a shallow lake sub-facies, delta front subfacies includes the following sedimentary microfacies, such as underwater distributary channel, mouth bar, far dams, front sheet sand and the former delta mud, etc. The main sedimentary microfacies in shallow lake sub-facies include shallow lake sand and shallow lake dam. Depending on the color, structure, characteristics of sedimentary structures of the rock,3kinds of main rock types in this area can be divided into the following:mudstone, sandstone, and siltstone. Exactlly, mudstone is mainly divided into massive mudstone, gray shale and plant debris mudstone; sandstone can mainly be divided into argillaceous sandstone, siltstone and fine sandstone.In the use of sediment grain size, sedimentary structures, stratigraphic thickness, sand body thickness and other factors analytical methods, the sub—layers sedimentary microfacies are comprehensively analyzed in ES3reservoir of Wen10Oil field. Based on the phrase analysis of single well, flat sedimentary microfacies distribution map for each small layers are made, and the facies model is established for this area.Sedimentary facies model in this area:the shallow lake subfacies is relatively developed in the upper ES3reservoir and the middle ES3reservoir, most of single layers develop shallow lake sand and shallow lake sand dam microfacies, a small number of single layers develop delta front deposition, in which sheet sand microfacies is dominant, while the underwater distributaries channel and mouth bar are developed rarely. The delta front subfacies is developed in the top of Lower ES3reservoir, in which distributaries the underwater channel and mouth bar microfacies is dominant, the mouth dam is relatively more developed. near the mouth dam of the lake at one end, because of the dual role of the lake waves and the river, the fine-grained material is transported to some further place to deposit, forming the distal bar microfacies around the outer edge of the mouth dams, but which is relatively developed rarely; the sheet sand microfacies is developed by the lake transportation of remote lake sediment deposited the outflank delta from. The bottom of Lower ES3reservoir is developed delta front subfacies and shallow lake facies, in which the sheet sand microfacies and shallow lake sand microfacies relatively developed.In addition, this paper also discuss the connection between sedimentary microfacies and the characteristics of the reservoir sand body, sedimentary microfacies in extent constraints the sand body on the horizontal and vertical distribution, so the different sedimentary microfacies sand bodies have obviously different properties and oil-bearing ability. Sedimentary characteristics of the sand body control the reservoir types, as well as sedimentary microfacies distribution control the distribution of reservoir. The sand thickness and sand size distribution are controlled by sedimentary microfacies, viewing from ES3reservoir in Wen10Oil field.