Sedimentary Facies and Reservoir Characteristics Analysis of the Permian Pingdiquan Formation in the Huoshaoshan Oilfield

The objective of this study is to re-characterize the sedimentary facies and reservoir properties of the early Permian Pingdiquan succession in the Huoshaoshan (HSS) area as a self-generated tight oil reservoir, and to provide new insights for future hydrocarbon development in the Huoshaoshan oilfield. This study combined seismic facies, single well lithofacies, sedimentary facies and reservoir characteristics analysis methods, to carry out a comprehensive study on the sedimentary facies type and distribution, reservoir physical characteristics and diagenesis of the Pingdiquan Formation in the HSS area, therefore was able to delaminate the favorable target of future exploration and production within this region. The Pingdiquan succession in HSS oilfield was deposited in a lacustrine delta depositional system, which consists of a complete lake transgression-regression depositional cycle, and is sub-divided into two sub-cycles and several secondary fining-upward cycles. The sediment sources mainly come from northeast and northwest, and the depositional center migrated to the northeast during time. The Pingdiquan Formation mainly developed medium-fine sandstone, siltstone, argillaceous dolomite and mudstone lithofacies. Interbedded sand and mud intervals were observed vertically. The main pore types of the Pingdiquan Formation are intergranular pore, dissolution pore and micro fracture. The results show that the reservoirs within the HSS anticlinal and Huodong syncline is of the best quality, where both conventional and unconventional reservoirs were developed, forming a favorable self-generated oil-gas enrichment area. By integrating geological characteristics and oilfield development status, this study deepens the overall understanding of sedimentary reservoirs in the study area and provides insights for further development direction. The findings can also be applied to help similar tight oil reservoirs’ efficient exploration and development.