Determination of Oil in Place, Ratio of Initial Free Gas to Oil, Reservoir Rock Properties from Limited Pressure Data

摘要

This study presents a pressure transient analysis technique forrndetermining the initial oil-in-place and the ratio of initial gasrnto oil, within the drainage area of the test well. The method isrnbased on a combination of the material balance equation, therncumulative production history, individual well rate history andrnPVT data of the reservoir, with limited well test pressure data.rnThe solution method considers the variable rate productionrnhistory of each of the wells and combines this data with arnglobal pressure data analysis approach as opposed to thernusually employed approach of applying each method inrnisolation, which often produces erroneous results.rnThe analysis procedure allows every detail of the reservoirrndevelopment, rate changes at every well from inception,rnglobal (reservoir wide) and local (individual well) fluctuationsrnin pressure to be included in the overall results. Localrnvariations in reservoir rock properties at the well locations arernalso accommodated in the method. By modifying the analysisrntechnique used for solving the linear material balance, arnmethod is derived that allows the simultaneous determinationrnof the original oil-in-place, and the initial ratio of free gas tornoil in the reservoir, without the previous knowledge of one orrnthe other from an independent source, a requirement that isrnoften needed for such solution. A Dynamic Material BalancernProgram (DMBP), a Visual Basic based program, wasrndeveloped to implement the solution procedure presented inrnthis paper.