Geological Characteristics And Modeling Of Complex Fault-block Reservoir In Abu Gabra Formation In Fula North Oilfield,Sudan

Fula North oil field in the study area is one of the main fields of Fula sag,this paper takes the Abu Gabra1 section of the lower Cretaceous as the research object,comprehensive use of seismic,logging,core and other geological data,has carried on the high resolution sequence stratigraphy to work area,fine structure interpretation,sedimentary micro equal geological research,finally through 3 d geological modeling method based on the results of the study on the characterization of intuitive.Through the formation of two marker layers,using synthetic recording technology to complete the calibration of large layers.Then,based on the principle of high resolution sequence stratigraphy,we identified the interface of three different levels of base level cycles,divided Abu Gabra1 group into one long-term cycle,6 medium-term cycles,and 42 short-term cycles,and established a fine high resolution sequence framework.By using coherent volume technique and seismic plane slicing technique,112 faults in the large working area are explained in the seismic section.One fault of grade 2,two faults of grade 3,as well as parallel faults,x-type faults and y-type faults were identified from the faults,and the level and classification of faults were completed.Through the establishment of velocity field,the drawing of MSC1-MSC6 top layer structure diagram is completed.According to the analysis of core and logging data,braided river delta plain and braided river delta front facies are mainly developed in the work area,and the main sedimentary microfacies include distributary channel,distributary bay,underwater distributary channel,underwater distributary bay,estuary dam,sheet sand,etc.After identifying the provenance in the northeast direction of the working area by sandground ratio,the coring section,the single well,the section and the whole working area of the coring well were studied in detail.There are few coring Wells and sections in the working area,based on the only core analysis.The reservoir lithology was identified as feldspar quartz sandstone dominated by medium sandstone,and the reservoir developed two types of primary and secondary pores,as well as three types of lamellar,neck-shaped and pore shrinkage.It is concluded that the reservoirs in the working area are medium-low porosity and permeability reservoirs,and the relationship between porosity and permeability is established.On this basis,the intersections of porosity,permeability and saturation with good correlation were established.Based on the above research results,the sedimentary facies model and reservoir attribute model are built by sequential gaussian algorithm in deterministic modeling method and stochastic modeling method respectively.It can be seen from the analysis that the reservoir physical properties in the working area are well correlated with the sedimentary microfacies,among which the reservoir physical properties of distributary channel,estuary dam and underwater distributary channel are the best.The variation amplitude of reservoir physical property in the direction of provenance is more gentle than that in the direction of vertical provenance.Finally,the accuracy of the model is verified by comparing the reserves calculated by the model and the reserves calculated by the geological volume method.