Application of Decline Curve Analysis on Some Wells in X&Y Libyan Oil Fields Using Analytical Method & OFM Software

Abstract Production decline curve analysis extrapolation is one of the oldest and most often used tools of the petroleum engineer. The various methods used always have been regarded as strictly empirical and generally not scientific. This work presents basic concepts and applications of decline curve analysis (DCA) in determining the remaining, total reserves and forecasting future production rate. Details of comprehensive conventional analysis techniques of the production history data using excel spreadsheets are conducted. The main objective of this study is to make a comparison between Arps method and OFM software used in decline curve analysis. Decline curve analysis was applied on seven oil vertical wells namely X-01, X-02, X-04, Y-01, Y-02, Y-03 and Y-04, X & Y oil fields belonging to Zueitina Oil Company. Decline curve analysis has been used to provide a best-fit equation for series of data point by least squares method. This method has been proved useful for decline curve analysis to evaluate the initial decline rate (ai), initial rate (qi) and the decline exponent (b), which can be used to plot the declining rate versus time after calculating the future rate at any desired time and calculating the reserves from certain time to an economic limit. The remaining reserve obtained from analytical method for Y field is about 2.64 MMstb for all the four wells and the remaining for X field is about 2.7 MMstb, and the results are closer to remaining reserve that gotten from OFM software. Also, the results obtained from RAMA method is near from the results from the Excel and OFM. The best wells in productions are well X-02, Y-02 and Y-04. For both in production and remaining maybe due to the location and reservoir rock properties. Well Y-01, Y-03 and X-01 they have the lowest remaining and oil production.