Study On Reservoir Prediction Of Oolitic Beach In Feixianguan Formation In LM Area Of Eastern Sichuan Basin

The LM study area in Eastern Sichuan Basin is located in the favorable facies belt of the Permian and Triassic reefs and beach reservoirs on the west side of the Kaijiang-Liangping Trough.The overall sedimentary deposition in the Feixianguan period was inherited from the Late Permian sedimentary background,carbonate platform gradually deposited and the deepwater troughs were filled until the end of the Feixianguan period,which the paleotopography is the quasi-plain process.The study shows that the oolitic beach reservoir is a product of carbonate platform facies in the Feixianguan period,and the platform marginal facies and the intraplatform shoal facies are more conducive to the development of the reservoir.This area is located near the fringe facies belt of the carbonate platform in Feixianguan period.It is an advantageous area for the development of the oolitic beach reservoir.However,the thickness of the oolitic beach reservoir in the LM area of Eastern Sichuan Basin is thinner than that in the adjacent area,and the heterogeneity is not uniform.The characteristics of oolitic beach bright spots are not obvious enough,the physical properties of the reservoir are poor and belongs to the low-porosity and low-permeability reservoir,and the relationship between gas and water is complex.Fractures are important permeable channels in the Feixianguan Formation reservoir in the study area.They play a key role in improving the osmotic performance of reservoirs and increasing production.Fractures can connect various pores to form a seepage network system and greatly improve reservoir performance.Fracture detection is a very important technology in low-permeability oil and gas reservoir prediction technology,especially in the Feixianguan Formation reservoir in the study area,which fractures are the main controlling factors for the production of single well.Theoretical study and rock sample testing carry out at home and abroad,which the most successful ones are the clastic reservoirs with high porosity and permeability.But for the characteristics of the low-porosity and low-permeability carbonate reservoirs,in the shoal and marine strata and the Feixianguan Formation of the LM area,hydrocarbon detection is very difficult.In view of the above difficulties,this paper starts from the actual seismic data and well logging data that have been mastered in the LM region,which takes the reservoir prediction,gas-water identification and fracture prediction of the Feixianguan Formation as the main research contents.On the basis of summarizing the previous scholars study of the oolitic beach in the Eastern Sichuan Basin:First,by summarizing the characteristics of the oolitic beach logging and seismic response,and comparing it with the neighboring area,we established a oolitic beach recognition model in the LM area.Secondly,the palaeogeomorphologic reconstruction methods which combined with attribute analysis techniques were used to classify the favorable facies belts of the oolitic beach,and the intrinsic links between the favorable facies belts for the development of the oolitic-beach reservoir and the seismic microfacies of the Feixianguan Formation were clearly defined.Then,through the fine calibration of reservoir horizons and the use of inversion techniques,the vertical and horizontal distribution characteristics of the shoal reservoirs are finely characterized.Fracture prediction is carried out,and the coherent attributes that are sensitive to the identification of fractures in the target layer are preferably selected,and the fracture distribution of the target layer is predicted.Finally,the research on gas-water identification in the target layer is carried out.The sensitive attributes of the target layer are used to characterize the distribution of gas and water in the target layer.With the previous results,comprehensive predictions are made for the favorable areas with oil and gas in the study area.