Workflow for applying simple decline models to forecast. Decline curves analysis through the arps method has been historically the tool more used to make wells reserves forecast, due to its simplicity and low cost. If one has a need to convert decline factor di to the actual annual decline in %. Vol volume under the curve segment adjusted for historical production. Analysis of production decline in waterflood reservoirs. The product will save significant man hours over traditional decline curve analysis software. The same decline techniques cannot, and should not, be applied to all fields and all drive mechanisms. Pdf analysis of production decline in waterflood reservoirs. Arnold and anderson 1908 presented the first mathematical model of dca. 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. By predicting production behavior at different points in time based on the wells past production history, analysts are able to identify well problems and predict performance and estimate ultimate recovery eur for a single well, or a group of wells on a. Hyperbolic decline curves have been used in many cases, particularly in the late history of pressure supported production.
Recent efforts in the area of decline curve analysis have been directed toward a purely computerieed statistical approach, its basic objective being to arrive at a unique unbiased interpretation. Nov, 2012 use the decline curve analysis toolbar to view completions data in just one or two clicks. Forecast the future y factor base d on the reference. Historically, decline curve models were derived based on observations of production, loss ratios, and bfactors. For exponential decline it is a constant with time. However, most curve analysis is done by computer today, promoting a blackbox approach to engineering and leaving engineers with little background in the fundamentals of decline analysis. In recent years, production decline curve analysis has become the most widely used tool in the industry for oil and gas reservoir production analysis. The decline curve will find the economic limit line at some time. We found in the pod and operating the pod wells simpson 1 that any analysis that treats an unconventional reservoir as darcy flow through a porous. Larkey 1925 proposed the leastsquares method to extrapolate the. Analysis of production decline curves poston, steven w. Crains petrophysical handbook reserves from decline curve. New decline curve analysis techniques to allow the analysis of transient data.
If co 2 is injected at a constant pressure, the rate will gradually decline. Depletion rate also can be connected to decline curves. Depletion has a fundamental role in the extraction of finite resources and is one of the driving mechanisms for oil flows within a reservoir. In advanced production decline analysis and application, 2015.
The production forecasting guidelines will address the following types of decline analysis. 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. The harmonic decline is the special case of equation 1 when the b exponent equals one. We would like to clarify that our study and the discussions in this article are limited to twophase fluid flow. 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, to qualitatively judge the. Production rates decline as a function of time owing to loss of reservoir pressure and changing relative volumes of the produced fluids. If your connection is slower, you will want to download the files separately. 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. Transient flow regime could last for several yeaars, during which hyperbolic decline analysis will yield a value of b 1 5. Apr 12, 2019 in the equation below, qi initial production rate, qt the production rate at the given time, t time, diinitial decline fraction, b hyperbolic exponent from 0 to 1.
The type curves based on the arps equation are still used frequently for production decline analysis at the pseudosteadystate period. Decline curve analysis is a long established tool for developing future outlooks for oil production from an individual well or an entire oilfield. Decline curve analysis in east almabrouk field case. Decline curve analysis for production forecasting based on. Advanced production decline analysis and application starts from the basic concept of advanced production decline analysis, and thoroughly discusses several. Decline analysis and reserves estimation based on decline analysis should be fundamentally grounded in a good understanding of what factors control the decline. Decline curves are one of the most extensively used forms of data analysis for evaluating reserves and projecting future production. These work indicate that the double porosity model predicts an initial high flowrate followed by p sudden rate decline and a period of constant 1. 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. Decline curve analysis is a means of predicting future oil well or gas well production based on past production history.
In this study the actual oil rate technique is applied under decline curve analysis d. Typewell analysis improves decline curve estimation oil. Values of b 1 are not consistent with decline curve theory, but they are sometimes encountered, and their meaning is explained below. Please try to fit the given production data in the spreadsheet, and report whats your b factor and estimated ultimate recovery. My approach is to iteratively solve for the b factor and initial decline terms that are implied by company guidance. Problems and limitations of decline analysis theory and mathematical basis for analyzing decline exponential, harmonic and hyperbolic declines factors affecting decline methods type curve matching felkovich curves examples and problems identifying opportunities using decline curve analysis. A decline curve analysis model based on fluid flow mechanisms. Dca is applied for wells and reservoirs production forecasting. Fetkovich 1990 indicated that a value of b 1 should not be used for reserve determination 6. An ideal decline curve for shale wells would be able to forecast linear flow followed by boundarydominated flow. Oil and gas decline curves rock river minerals, lp. Production decline curve an overview sciencedirect topics. Finally, the long term model behavior can be used in the decline curve analysis dca module of citrine to provide a practical assessment of the longterm rate decline profile and a range of eur values.
The effective decline factor d is a stepwise function that is in better agreement with data recording practices. 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. The full size fetkovich typecurves can be ordered from the book order department of spe. The case of eagle ford linnea lund production of oil and gas from shale is often described as a revolution to energy production in north america. Decline rate or b factor choice can use p90, p50, p10, or another method. Determine the amount of prior production and add that to the partial eur for the actual estimated ultimate recovery.
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. As a result, evaluators have modified the original dca to incorporate a b factor larger than 1. Procedure for calculating estimated ultimate recoveries. Frailey 2009 points out that decline curve analysis may be used to estimate how much co 2 may be injected into an aquifer, in the same way as the total production from an oil reservoir may be estimated. Production decline curve analyses are the most widely used tool in the industry for oil and gas reservoir production analyses. Cumulative production semilogarithmic axes straight line trends on this plot results in highly optimistic reserves 3p. Production decline curves can be classified as follows. Oil, gas and water saturation levels are important factors and refer to the. The b factor regulates the initial steepness of the decline curve. A program, and screening data points to calculate remaining and recoverable reserves. The decline curve shows how oil and gas production rates decrease over time.
When applying arps in shale plays we find b values greater than 1 that mathematically are possible but its not correct to use it to make the reserves forecasting as we will see later. The use of type curves for decline curve analysis is demonstrated with examples. Since the beginning of this century the shale oil production has increased from practically zero to currently supply almost half of the u. Decline curve analysis is the most currently method used available and sufficient 1. Decline curves are generally easy to use, but type curves usually provide better forecasts for complex reservoirs. Your manager asks you to perform decline curve ana. Traditional decline generates a forecast of future production rates based on the equations defined by arps. Quickdecline was written by petroleum engineers as a tool to make quick and easy decisions. This book will serve as an authoritative reference on modern production decline curve analyses, including details of some recent advances in the technology. The utility of type wells in predicting initial rates and shortmedium term decline does not necessarily depend on the. Using decline curves to forecast waterflooded reservoirs. The report also investigates how the density of the petroleum affects the decline curve. Calculate ooip using 35% recovery factor if the reservoir has undergone tertiary recovery then also determine the tertiary eur.
Decline curve analysis dca is an empirical method for rate decline analysis and rate forecasting published by arps in 1945. Advanced production decline analysis and application starts from the basic concept of advanced production decline analysis, and thoroughly discusses several decline methods, such as arps, fetkovich, blasingame, agarwalgardner, npi, transient, long linear flow, and fmb. The most popular decline curve is that which represent the decline in the oil or gas. Decline curve analysis nontechnical, easy read published on august 10, 2016 august 10, 2016 11 likes 0 comments. Nodal analysis procedures not covered explicitly in this book tend to rely heavily on ipr techniques andor decline curve analysis and have been of limited value in unconventional fields. This chapter deals with analysis of decline curves during the transient and pseudosteadystate flow periods.
The conventional analysis of production decline curves for oil or gas production. A practical systematic introduction to each method helps the reservoir engineer understand the physical and mathematical models, solve the type curves and match up analysis, analyze. L337tech llc also offers paid training for quickdecline. Advanced production decline analysis and application. Dca parameters are easily input to fit your data and forecast production on the fly. Your manager asks you to perform decline curve analysis for a shale well in permian basin wolfcamp reservoir.
Decline curve analysis three basic decline curve equations. In this study decline analysis was applied for wells, and whole field. Decline curve analysis for estimating eurs and ooips. Before the availability of computers, decline curve analysis was performed by hand on semilog.
Verification of decline curve analysis models for production. The hyperbolic curve requires estimation of both di and the exponent b. Mead9 noted in his discussion of b factor decline curve exponent that. Dcadvantage cloud based decline curve analysis youtube. A value of b 0 corresponds to exponential decline, values of b 0 and b 1 corresponds to harmonic decline. The application of decline curve analysis dca in unconventional plays could be. Decline curve analysis dca is used to predict the future production of oil and. The traditional decline analysis can also be modified to a terminal limiting decline rate. Decline curve analysis free download as powerpoint presentation. Production forecasting decline curve analysis petrowiki. The initial decline rate controls the rate at which the type curve declines. Initial flowrate in the context of the exponential decline curve analysis, this is the flowrate essentially on the first day of production, although the average flowrate for the first full month could also be used. Production decline data from different types of waterdrive reservoirs were analyzed as examples of using the new decline analysis model.
A decline curve analysis model based on fluid flow. Decline is proportional to a fractional power b of the production rate 0 b decline. Classifications of production decline curves and their practical uses are discussed with field examples including methods to forecast performance of horizontal and vertical fracture gas reservoirs. Prediction of reservoir performance applying decline curve analysis. If you have a fairly fast connection, you may wish to download the entire package. The fullsize fetkovich typecurves can be ordered from the book order department of spe. Finally, the cumulative recovery should result in a reasonable recovery factor, based on volumetrics. Types of decline analysis in production forecasting. The decline type of well 1 is exponential, and the remaining reserve calculated. Decline curve analysis dca is a graphical procedure used for analyzing declining production rates and forecasting future performance of oil and gas wells. Decline analysis curve an overview sciencedirect topics. Raghavan and ohaeri 19, and sageev zo also examined the rate dedine behavior of naturally fractured reservoirs. 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.
In the equation below, qi initial production rate, qt the production rate at the given time, t time, diinitial decline fraction, b hyperbolic exponent from 0 to 1. The remaining reserve calculation becomes more reliable whenever data points are well screening. Cutler 1924 also used the loglog paper to obtain a straight line for hyperbolic decline, so the curve shifted horizontally. The hyperbolic decline curve has a good fit to production data and in many cases the curve is close to harmonic. The b factor determines the initial steepness of the decline curve is generally a number between.
Practical decline curve analysis society of petroleum. Decline curve analysis is a long established tool for developing future outlooks for oil production from an. Decline curve analysis in unconventional reservoirs using a. Two main analysis methods are decline curve analysis and type curve analysis. Pro duction prediction based on reservoir simulator. C a numerical solution to twoparameter representation of production decline curve analysis, paper spe 16505 presented at the 1987 spe petroleum industry applications of. Factor, cluster, and multiple regression analysis show that production data from the sampled barnett shale and jonah field databases group separately from the slickwater parameters. View decline curve analysis research papers on academia. Spe textbook series, volume 9, society of petroleum engineers. The equation shows that the respective decline curves are generated based on the value of b.
A practical systematic introduction to each method helps the reservoir. With inputs for multiple scenarios, running sensitivities on the dca inputs is fast and easy. Case study of a lowpermeability volatile oil field using. This factor can be used provided that the wells are grouped properly and exhibit a characteristic behavior. Prediction of reservoir performance applying decline curve. The cumulative oil production after the production decline upon decline time t can also be evaluated based on the total reservoir compressibility.
Conversely, predictions from the decline history assumes that no significant changes in these factors will take place. Decline curve analysis forecasting logarithm free 30. Decline curve analysis dca is used to predict the future production of oil and gas, and it has been widely used since 1945. Types of decline analysis in production forecasting petrowiki. Mathematics the arps decline curve analysis approach4 was proposed nearly sixty years ago. Multiwell decline curve analysis shows the validity of the variables s skin, k, ooip, ultimate fractional recovery and gor versus fractional recovery evaluated from each wells type curve match point.
He only indicated that exponential decline b0 is most common and that the coefficient b generally ranges from 0 to 0. Nominal decline is a continuous function and it is the decline factor that is used in the various mathematical equations relating to decline curve analysis. Although a decline curve can be depicted by one of the models shown above, in many cases the decline is represented by an assimilation of the hyperbolic and exponential models. Our decline curve analysis method is modeled after arps 1956. That will be is the end of oilfield production life, conditioned by present technology, production cost, contracts and state regulations. 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. Study on the decline analysis of oil well stimulation rule. Decline curve start date when you want the decline curve to be displayed on the chart. The drillnomics di factor is a similar representation of the initial decline rate in arps and in conjunction with the b factor will enable the user to easily model the hyperbolic section of a decline curve when fitting visually to well production data. A new theory for interpreting rate decline trends in. 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. Depletion and decline curve analysis in crude oil production. These variables must all give consistent and reasonable numbers when compared with each other.
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