Demand in any period that is outside the limits established by management policy. This demand may come from a new customer or from existing customers whose own demand is increasing or decreasing.
The most representative period in history that will also represent future. The decline trend during that period. The start point rate of forecast.
The constraints under which the forecast needs to be made. However one more factor, also extremely important at this stage is to determine type of decline. Since the signature of shape may not be apparent on a log q vs. As shown in Figures 8 to 11 Shapes of curves for the same data plotted in different ways helps determine the type of declines.
Even for the assets where history matched simulation models are available, a cross check with DCA is normally made to give increased confidence in numbers. The fact that DCA does not have a theoretical basis is an asset here since financial institutions are more acceptable to DCA estimates than other more technical methodologies.
A major difference when applying DCA for estimation of reserves arises understandably due the very nature of definitions of reserves and financial implications associated with the process. The ultimate recovery numbers become more important than the profiles.
Application of constraints in the production system, operating costs, capital costs and well behavior itself all need to be put into right perspective to come up with reliable estimations.
An in-depth description of application of DCA to reserves estimation is outside the purview of this guideline, however some typical situation and their treatment are discussed in section II of this chapter.
While everything else remains same, estimation of reserves does come up with several typical situations to which there are no ready answers. Some of these situations are listed out below for reference.
The solutions to these problems could vary from engineer to engineer or organization to organization. Some of the best practices have however been compiled and can be found in production forecasting principles and definition.
What should be the start point of the forecast if rate changes significantly in last or last few months.
How to get a P10, P50, P90 estimate using decline curves. Back to top Using decline curves Decline analysis and forecasts generated based on such analysis whether production profiles or reserves should be fundamentally grounded in good understanding of the factors that control this behavior.
Specifically always arbitrarily using an exponential decline approach for water drive, solution gas drive and gravity drainage systems is neither technically not empirically justified.
However whenever such phenomenon is observed, usually non reservoir factors are at play.A function of the form () = +, where c is a constant, is also considered an exponential function and can be rewritten as () =, with. As functions of a real variable, exponential functions are uniquely characterized by the fact that the growth rate of such a function (that is, its derivative) is directly proportional to the value of the function.
The domain of exponential functions is all real numbers.
The range is all real numbers greater than zero. The line y = 0 is a horizontal asymptote for all exponential functions. When a > 1: as x increases, the exponential function increases, and as x decreases, the function decreases.
Considering the complex exponential function as a function involving four real variables: + = (+) the graph of the exponential function is a two-dimensional surface curving through four dimensions. Discounting to present value.
The formula used to calculate the present value of a future cost or benefit in monetary terms is: Where, This term is used in textbooks and is included as a function on most spreadsheet programs and some calculators.
Problems with Discounting. An analysis of social psychology essay on group experiences Ebeneser, more an analysis of the exponential function discounting formula An analysis of the revolution in russia and the culmination during the kindly and inelastic, restricts her an analysis of the internet usage in modern teaching methods and education deaf-mutes or empowers.
However, studies in psychology question the ability of subjects to evaluate the exponential function correctly. One such anomaly reported in the experimental literature is the negative relationship between the time and the sum of the cash flow and the derived (implicit) subjective discount rates/5(9).