Reservoir Geological Modeling Of Fractured Dolomite In Wumishan Formation, Yanling Buried Hill

Yanling oilfield located in the middle of Raoyang depression in Jizhong,which is carbonate buried hill and mainly composed of dolomite.Reservoir bed is middle proterozoic Jixian system Wumishan formation.It developed in November 1977 and has experienced four large-scale development and adjustment phase,has entered in final phase now.This paper researched structural characteristics,fracture system,reservoir characteristics,fluid properties.A variety of modeling methods are explored and preferred by ant tracking and sequential indicator simulation to built hierarchical control model of fracture developed zone and reservoir developed zone.Recalculated dynamic reserves with volumetric method by Petrel. The recoverable reserves were predicted by a variety of methods such as bring-into-oil curve analysis method,potential decline curve analysis method and cumulative production curve analysis method.Evaluated the potential of remaining oil by dynamic and static method.Through above research,this paper obtains the following research results and conclusion:1) Through stratigraphic correlation and structural modeling, we know that Yanling buried hill is half of a tectonic mountains from west to east and eluvial conglomerates are reserved.Stratigraphic thickness is thin in the south and thick in the north,but erosion is strong in the south.Stratigraphic sequence from top to bottom is Longshan formation(Qnl), Wuyi member(Jxw1) Wuer member(Jxw2). Yanling main fault is the NNE trending, about 18 km long and fault distance is large in middle and small in both sides.Whole structural shape is three steps from south to north and formed two nose structure in the EW trending.There are 45 faults at the top apart from the main fault.2) Through the reservoir evaluation, we realize that the fracture of Yanling reservoir is developed,the type of reservoir rock is various and reservoir space is mainly the large fractures and pores. Vertical fracture is developed.fracture is oily andthe main flow channel.The grade ? of facture developed zone with good penetration properties is mainly composed of strike factures,dissolved pore and limestone cave.It is the main channel for fluid migration and reservoir and has a large volume of space;The grade ? of facture developed zone with good penetration properties is mainly composed of dip direction fracture and has good reservoir capacity;The grade? of facture developed zone is mainly composed of oblique crossing fracture and has a limited reservoir capacity.3) Based on the study of fracture developed zone and reservoir developed zone,The fracture developed zone and reservoir developed zone models were established.The fracture model was added to the seismic ant body data, so the credibility and accuracy of fracture prediction between wells was better than only use sequential indicator simulation.Research shows that the facture developed zone is close to the top of the buried hill,the development of fracture near the fault is obvious and the heterogeneity in vertical is more strong than in horizontal.The research results of modeling show that grade I of fracture developed zone is the highest, the grade ?of facture developed zone is the second and the grade ? of facture developed zone the worst.4) Combined with the data of the oil, gas and water distribution, established several model such as oil saturation,porosity,oil thickness,etc.Research results of oil,gas and water distribution model shows that the reservoir is massive bottom water with small height,good connectivity,uniform oil water interface and pressure system both in south and north.Wuyi member is the main oil bearing strata with large oil area.5) Research results show the static geological reserve is 1813.24 × 104 t,recoverable reserve is 557.94×104t.After evaluating the potential of remaining oil,discovered several main remaining oil distribution blocks such as the injection Zone of nitrogen and two "attic oil" block in Yanbei, twelve "attic oil" block Yannan,etc.Researched and established several potential blocks with economic value such as the enriched oil zone in the injection zone of nitrogen Yanbei,5 "attic oil" blocks such as the top of Yannan wellblock,Yan 1 wellblock,Yan 37 wellblock,etc.