Research On Productivity Equation Of Two-phase Flow In Fractured-vuggy Reservoirs

With the technical progress of exploration and development,the global exploration and development is developing from conventional reservoirs to unconventional reservoirs.The fractured-vuggy carbonate reservoirs belong to the type of unconventional reservoirs,the reservoirs have large reserve volume and high productivity,it is a kind of much rich reservoirs.Be different with conventional clastic reservoirs,the most obvious characteristics of fractured-vuggy carbonate reservoirs are various scales of fracture and vuggy fabric and extreme heterogeneity.The distribution of oil and water in fractured-vuggy carbonate reservoir is complex,the fluid flow pattern is complex.These make a great deal of difficulty in the development of fractured-vuggy reservoirs.The productivity of oil well is associated with kinds of development indexes,and how to predict the productivity of oil well is very important to efficient development of whole field.Therefore,studying on productivity prediction of fractured-vuggy carbonate reservoir and establishing productivity prediction model for fractured-vuggy carbonate reservoir has great significance.To study on the productivity of fractured-vuggy carbonate reservoirs,this paper had made a research on the two aspects of the establishing productivity equation and the analyzing the practical application.According to the characteristics of fractured-vuggy reservoir,based on the equivalent continuous medium model and the pipe flow-seepage flow model,and in combination with the flow law of oil-water and oil-gas two-phase,this paper obtained the productivity equations and pressure equation of oil-water and oil-gas two-phase for fractured-vuggy carbonate reservoir.And based on the actual production date in an oil well,this paper calculated the oil production and the pressure.Then through computer programming calculation,this paper analyzed the influence factors on productivity.This paper obtained the following achievements and understandings:(1)Using the equivalent seepage resistance method,we obtained the equivalent permeability of fractured-vuggy carbonate reservoirs in different parallel connection model(vuggy-fracture-matrix,fracture-vuggy-matrix,matrix-vuggy-fracture),based on the equivalent continuous medium theory,this paper established parallel connection productivity equation of oil-water and oil-gas two-phase for fractured-vuggy carbonate reservoir.(2)Based on the capillary bundle model,we obtained the boundary condition of vuggy units and fracture units,and established series connection productivity equation of oil-water and oil-gas two-phase for fractured-vuggy carbonate reservoir.(3)Based on the actual production date in an oil well,this paper calculated the oil production and the pressure.Then through computer programming calculation,this paper discussed the influence factors on productivity,such as oil/water ratio,oil/gas ratio,fracture width,fracture length,etc.Through the research,a complete productivity prediction and analysis method of two-phase for fractured-vuggy carbonate reservoirs is found.the productivity equations established in this paper has a certain theoretical significance for understanding the fractured-vuggy connection mode and the fractured-vuggy factors of fractured-vuggy carbonate reservoir,and also has a certain guiding role for analyzing productivity of fractured-vuggy carbonate reservoir.