Using Volumetric and Decline Curve Analysis as Techniques for Estimating Reserve

Management’s decisions are dictated by the anticipated results from an investment. In the case of oil and gas, the Petroleum Engineer compares the estimated costs in terms of dollars for some investment opportunity as against the cash flow resulting from production of barrels of oil or cubic feet of gas. This analysis may be used in formulating policies for exploring and developing oil and gas properties. The present work therefore aimed at comparing two of the various methods of estimating reserve. These methods are: Volumetric and Decline Curve Analysis. The volumetric method of estimation was based on a detailed geological analysis. The Area Vs. Depth graph was plotted using planimetry readings, and this was used to estimate the reservoir bulk volume. Arithmetic averages of petrophysical data from five wells were used. The Net-To-Gross ratio of the average sand thickness was estimated from log responses; and thus, the reserve was estimated with this method. The decline curve analysis was based on observed production history. The reservoir used in this work shows an exponential decline trend with a constant. Thus, the-reserve was estimated with this method.