Study On Reservoir Geological Model Of Guantao Formation In Miaobei Area,Jidong Oilfield

The Miaobei area of Jidong Oilfield is located in the footwall block of Xinanzhuang fault of the Nanpu Sag in the northern part of the Huanghua Sag.Through decades of rapid development,it is currently in the late adjustment stage,there are some important factors that restrict the improvement of recovery ratio: the layer is not finely divided,the microstructural features of reservoir are unclear,the distribution of reservoir parameter characteristics is not clear,and the lack of fine reservoir 3D geological model.Based on the predecessors' research results and the comprehensive use of core,logging,seismic and logging data,research of fine stratigraphic framework establishment,reservoir microstructural feature characterization,sedimentary microfacies identification and division,reservoir parameter distribution description is launched in Guantao Formation.Finally,the three-dimensional geological model of the reservoir was established,and the following points were obtained:(1)According to the establishment of the 3 sets of contrast signs of the layers of Guantao Formation that covering the whole district,Guantao Formation was totally divided into 4 oil layer group and25 layers,of which 7 layers in the 3 overlying oil layer groups and 4 layers in the underlying sand layer group.Each layer shows a certain positive cycle and is stable in the whole area.(2)Guantao Formation is mainly controlled by the sedimentary environment of the braided river.The overlying I oil layer group and the underlying IV oil layer group are highly hydrodynamic,and the middle II oil layer group and the III oil layer group are weakly hydrodynamic.Controlled by the southeast source area,the heart beach and the braided channel are mainly distributed in the middle of the study area,and the two sides are deposited in the flood plains dominated by mud and silty.(3)The structural characteristics of the Guantao formation are mainly controlled by the southwestern Zhuang fault in the north and the top structure of each small layer shows obvious inheritance.The closer to the upper part,the larger the closed height and the closed area of each trapped nose structure in the upper small layer and the appearance of each layer also becomes steep.(4)The distribution characteristics of the physical parameters of the reservoir are mainly controlled by the sand thickness of the braided channel and channel bar and the high value area of porosity is located in the high-value area of the center of the braided channel and channel bar.The high-value zone of permeability has the same range of porosity distribution in the middle class II and class III oil layers.In the upper class I oil layer group,it is mainly distributed on the first and last sides of the braided channel.(5)The channel bar sand has good physical properties and low heterogeneity which is a development zone of high-quality reservoirs of class I.The braided channel sand is highly heterogeneous which is the development zone of reservoirs of class II.The lateral variation of reservoir thickness and porosity in the middle class I reservoir is weak and the heterogeneity is relatively weak which is the main developmental interval of high-quality reservoirs.(6)The stability of braided river reservoirs is poor and the parameter changes faster in three dimensions.High quality reservoir sand distributed as potato shape and corresponds to the main part of the heart beach.The crude oil in the main producing layer is mainly concentrated on the corners of the fault.The established reservoir geological model provides the geological basis for the reservoir and production contradictions and the analysis of injection-production contradictions.Under the constraint of reservoir geological model,the adjustment of injection and production well pattern and the newly deployed well have achieved good benefits.