The Single Sand Body Reserch Of The Yan 9 Reservoir Group In Feng 5-13 Well Block Of Ordos Basin

The Feng 5-13 well area is located in the middle of Jihuang 32 block in the Ordos Basin.It is a key development area of the Jurassic Yan 9 oil layer group.The sand group was used as a unit for overall exploitation in the early stage,and good development results were achieved.With the continuous deepening of production,there are currently production problems such as rapid decline in production,poor water injection effects,and insignificant reservoir reconstruction effects.The main reason is that the reservoir sand body is not carefully studied,which leads to the connectivity of the sand bodies between injection and production well groups is not clear.In order to improve the current development status,the paper makes full use of geological,well logging and production performance data to identify sedimentary microfacies based on the fine division and comparison of single sand layers,focusing on single sand body analysis and inter-well sand body connectivity analysis.The adjustment of injection and production provides a geological basis.The relevant results and understandings are as follows:Guided by the theory of sequence stratigraphy,fine stratigraphic division and comparison were carried out,and the Yan 9 oil layer group in the Feng 5-13 well block was subdivided into 6single sand layers,and a single sand layer-level isochronous stratigraphic framework was established.It is clear that Yan 9₁^2-1,Yan 9₁^2-2,Yan 9₂^2-1 and Yan 9₂^2-2 are the main intervals with single sand body development.Combined with the regional sedimentary background,through the observation of cores and the identification of sedimentary facies,it is determined that each single sand layer in Yan 9 is a braided river delta plain subfacies,with four types of sedimentary microstructures developed by braided river channels,center banks,overflow banks and flood plains.The type of facies clarifies that the study area has experienced the process of"lake advancement-lake retreat-lake advancement"during the Yan 9 deposition period.On the basis of sedimentary microfacies research,using the four constraint conditions of logging curve shape change,inter-channel muddy sedimentation,sand body thickness change and sand body top elevation difference,a total of 12 channel sand bodies and 11 overflow sand bodies were identified in the study area.It is determined that there are three overlapping styles of sand bodies of different stages:separation,overlapping contact,and overlapping cutting;and there are three contact styles between sand bodies of the same stage:bay separation,butt joint and side cutting.According to the contact relationship between sand bodies,the sand body connectivity of the main single sand layer is analyzed.Vertically,two types of shale and physical barriers were identified in the study area,and the characteristics of the development of barriers and intercalations and the vertical connectivity range between sand bodies were clarified.Horizontally,the sand body connectivity types are divided into 3 major categories and 8sub-categories.According to the sand body connectivity,they are divided into 4 connectivity levels.The connectivity relationship of the sand bodies between injection-production well groups in each single sand layer is analyzed.Using production dynamic data,the results of the sand body connectivity between injection and production wells are verified,which is consistent with the actual development situation.