It involves matching production data history to an empirical equation and simply extrapolating the production trends. To estimate ooip we need to know the estimated ultimate recovery eur and the recovery factor we can get eurdirectly from a graph we use a standardized average recovery factorof 35% for all reservoirs undergoing. Production forecasting decline curve analysis petrowiki. Decline curve analysis is a long established tool for developing future outlooks for oil production from an individual well. Decline curve analysis dca is used to predict the future production of oil and gas, and it has been widely used since 1945. Case study of a lowpermeability volatile oil field using. Arnold and anderson 1908 presented the first mathematical model of dca. Production decline curve analysis the road not taken. Application of extended exponential decline curve analysis to the. A value of b 0 corresponds to exponential decline, values of b 0 and decline, and a value of b 1 corresponds to harmonic decline.
Oil and gas production rates decline as a function of time. With inputs for multiple scenarios, running sensitivities on the dca inputs is fast and easy. A decline curve analysis model based on fluid flow mechanisms kewen li, spe, and roland n. Initialization of decline parameters from linear regression for niger delta field data decline exponent decline rate the study computed the decline parameters thus. The decline curve analysis template for tibco spotfire allows you to quickly plot oil forecast curves on top of your actual production, using the arps hyperbolic equation. The production decline curves have two main functions, including a to determine the reservoir permeability parameter by matching the production decline curve with it, which belongs to quantitative analysis, and b to diagnose the production performance characteristics, that is. Black dots represent the outliers, whereas red dots are the oil rates included in the analysis. Hyperbolic decline curves have been used in many cases, particularly in the late history of pressure supported production.
The novelty of the proposed decline curve models is in the simultaneous understanding of the production, loss ratio, and b factor relationships for wells in unconventional reservoirs and the corresponding impact on reserve analysis. Prediction of reservoir performance applying decline curve analysis. While the hyperbolic decline model is more general, the other two models are degenerations of the hyperbolic decline model. When b 1, it is a harmonic model and when b 0, it yields an exponential decline model. We investigate the applicability of a densitybased approach for decline curve analysis for production at constant bottomhole pressure in dualporosity gas systems. Dm minimum decline rate decline rate at which hyperbolic projection becomes exponential segment null projection pressing this button causes a 0 or null projection to be input for the 1st decline segment. The hyperbolic curve requires estimation of both di and the exponent b.
In advanced production decline analysis and application, 2015. Decline rate or b factor choice can use p90, p50, p10, or another method. Before the availability of computers, decline curve analysis was performed by hand. The cumulative oil production after the production decline upon decline time t can also be evaluated based on the total reservoir compressibility. View decline curve analysis research papers on academia. This research assessed the effectiveness of arps decline curve analysis and recently established methods. Data points lying outside the type curve represent transient flow. Decline curve analysis is the most currently method used available and sufficient 1. Analysis using the li horne model for production data from spraberry oil field. The most popular decline curve is that which represent the decline in the oil or gas. A new theory for interpreting rate decline trends in.
The challenge with this equation is to determine simultaneously three parameters. The utility of type wells in predicting initial rates and shortmedium term decline does not necessarily depend on the. Calculate ooip using 35% recovery factor if the reservoir has undergone tertiary recovery then also determine the tertiary eur. Decline curve analysis three basic decline curve equations. Decline curve analysis in unconventional resource plays. Conversely, predictions from the decline history assumes that no significant changes in these factors will take place. Harmonic decline curve occurs when b1, so the equation is. The report also investigates how the density of the petroleum affects the decline curve.
Traditional decline generates a forecast of future production rates based on the equations defined by arps. Fetkovich recognized that decline curve analysis was only applicable during the depletion period ie. Decline curve analysis is a means of predicting future oil well or gas well production based on past production history. Exponential decline using the b factor value of zero is exhibited by a straight line on a semilog graph, whereas hyperbolic decline with b values ranging from 0. Depletion has a fundamental role in the extraction of finite resources and is one of the driving mechanisms for oil flows within a reservoir. Decline curve analysis is a long established tool for developing future outlooks for oil production from an individual well or an entire oilfield. Depletion rate also can be connected to decline curves. Well properties initial production ip rate and production decline rate were documented, and estimated ultimate recovery eur was calculated using two empirical production decline curve models, the. Dca parameters are easily input to fit your data and forecast production on the fly. Pdf verification of decline curve analysis models for production. Case study of a lowpermeability volatile oil field using individualwell advanced decline curve analysis. The traditional decline analysis can also be modified to a terminal limiting decline rate. Production data analysis of naturally fractured reservoir. Decline curve analysis for estimating eurs and ooips.
Forecast the future y factor base d on the reference. Decline curve analysis forecasting logarithm free 30. Thus, a major advantage of this decline trend analysis is inclusion of all production and operating conditions that would influence the performance of the well. The decline curve equations assume that production decline is proportional to reservoir pressure decline. Types of decline analysis in production forecasting. Values of b 1 are not consistent with decline curve theory, but they are sometimes encountered, and their meaning is explained below. With the decline parameters defined, the arps decline function becomes 1 0.
Oil well ratetime analysis continued oil well with n1 b. Depletion and decline curve analysis in crude oil production. A bestfit hyperbolic or exponential decline is fit to existing production data and extrapolated for 60 years 720 months. Production decline curves of tight oil wells in eagle ford. Determine the amount of prior production and add that to the partial eur for the actual estimated ultimate recovery.
Pdf analysis of production decline in waterflood reservoirs. The harmonic decline is the special case of equation 1 when the b exponent equals one. Mead9 noted in his discussion of b factor decline curve exponent that. Decline curve analysis dca is a graphical procedure used for analyzing declining production rates and forecasting future performance of oil and gas wells. Pdf verification of decline curve analysis models for. If you have a fairly fast connection, you may wish to download the entire package. Production decline curve analysis is a traditional means of identifying well production problems and predicting well performance and life based on measured oil well production. Cutler 1924 also used the loglog paper to obtain a straight line for hyperbolic decline, so the curve shifted horizontally. A curve fit of past production performance is done using certain standard curves.
The type curves based on the arps equation are still used frequently for production decline analysis at the pseudosteadystate period. Decline curve analysis free download as powerpoint presentation. Decline curve analysis is the most common method used in reservoir engineering calculations to predict future field production rates from historical production data. Additionally, short production profiles available are inadequate for accurate production decline analysis. One type of cline curve analysis involves the hyperbolic decline curve equation equation 1 in the equation box.
Typewell analysis improves decline curve estimation oil. Production decline curve an overview sciencedirect topics. The new model is based on the concept of logistic growth models. Prediction of reservoir performance applying decline curve. It is too early to determine whether the alternative decline curve that is tested, the scaling decline curve, has a better fit in the long term. Our decline curve analysis method is modeled after arps 1956. This method has been proved useful for decline curve analysis in order to estimate the initial decline rate d, initial rate qi and the hyperbolic exponent b, which can be used to plot the. A new empirical model has been developed and used as an alternative to traditional decline curve analysis with the arps equation. A decline curve analysis model based on fluid flow. This study derives typical production curves of tight oil wells based on monthly production data from multiple horizontal eagle ford shale oil wells. Vol volume under the curve segment adjusted for historical production. Analysis of production decline in waterflood reservoirs.
This may be the case still, even though ten years have past. An ideal decline curve for shale wells would be able to forecast linear flow followed by boundarydominated flow. A decline curve analysis model based on fluid flow mechanisms. The hyperbolic decline curve has a good fit to production data and in many cases the curve is close to harmonic. Pdf on mar 1, 2005, kewen li and others published verification of decline curve analysis. Decline curve analysis has been called the most commonly used and misused technique for forecasting future production and remaining reserves. Finally, the cumulative recovery should result in a reasonable recovery factor.
Procedure for calculating estimated ultimate recoveries of. Dt in the equations b and d are empirical constants that are determined based on historical production data. Decline curve analysis is not a curvefitting exercise, and it should not be limited to a single ratetime graph of each well in isolation, much less just any ratetime graph created by the sloppy defaults of most graphing programs. If your connection is slower, you will want to download the files separately. The production forecasting guidelines will address the following types of decline analysis. Analysis methods traditional background for traditional analysis decline curve analysis is a graphical procedure used for analyzing declining production rates and forecasting future performance of oil and gas wells.
Decline analysis routinely used by engineers to estimate initial hydrocarbon in place, hydrocarbon reserves at some abandonment conditions, and forecasting future production rate. Use the decline curve analysis toolbar to view completions data in just one or two clicks. But this is where decline curve analysis algorithms are these daysat a. Decline curve analysis is an exercise in seeing, understanding and predicting the reservoir and operational dynamics. Dca aims to determine qi, di and b 2 from historical production data. This course will give the learner a better understanding of how fundamental reservoir properties and drive mechanisms affect the shape of the production decline curve and how to avoid many of the mistakes commonly found in. What factors control shale gas production and production. In addition, conventional dca assumes constant flowing bottomhole pressure, drainage area. These three models are related through the following relative decline rate equation arps, 1945. Development of universal decline curve analysis technique. Decline analysis curve an overview sciencedirect topics. Oil, gas and water saturation levels are important factors and refer to the percentage of the pore vol.
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