Rate Decline Relations For Unconventional Reservoirs And Development Of Parametric Correlations For Estimation Of Reservoir Properties

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Rate-decline Relations for Unconventional Reservoirs and Development of Parametric Correlations for Estimation of Reservoir Properties

Author : Yohanes Aklilu Askabe
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (865 download)

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Book Synopsis Rate-decline Relations for Unconventional Reservoirs and Development of Parametric Correlations for Estimation of Reservoir Properties by : Yohanes Aklilu Askabe

Download or read book Rate-decline Relations for Unconventional Reservoirs and Development of Parametric Correlations for Estimation of Reservoir Properties written by Yohanes Aklilu Askabe and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-rate analysis and time-rate-pressure analysis methods are available to estimate reserves and study flow performance of wells in unconventional gas reservoirs. However, these tools are often incorrectly used or the analysis can become difficult because of the complex nature of the reservoir system. Conventional methods (e.g., Arps' time-rate relations) are often used incorrectly to estimate reserves from such reservoirs. It was only recently that a serious study was conducted to outline the limitations of these relations and to set guidelines for their correct application. New time-rate relations, particularly the Duong and logistic growth model, were introduced to estimate reserves and forecast production from unconventional reservoirs. These new models are being used with limited understanding of their characteristics and limitations. Moreover, well performance analyses using analytical/semi-analytical solutions (time-rate-pressure) are often complicated from non-uniqueness that arises when estimating well/formation properties. In this work, we present a detailed study of the Duong model and logistic growth model to investigate the behaviors and limitations of these models when analyzing production data from unconventional reservoirs. We consider production data generated from numerical simulation cases and data obtained from unconventional gas reservoirs to study the quality of match to specific flow regimes and compare accuracy of the reserve estimates. We use the power-law exponential model (PLE), which has been shown to model transient, transition and boundary-dominated flow regimes reliably, as a benchmark to study performance of Duong and logistic growth models. Moreover, we use the "continuous EUR" approach to compare these models during reserve estimation. Finally, we develop four new time-rate relations, based on characteristics of the time-rate data on diagnostic plots. Using diagnostic plots we show that the new time-rate relations provide a quality match to the production data across all flow regimes, leading to a reliable reserve estimate. In a preliminary study, we integrated time-rate model parameters with fundamental reservoir properties (i.e., fracture conductivity (Fc) and 30 year EUR (EUR30yr)), by studying 15 numerical simulation cases to yield parametric correlations. We have demonstrated a methodology to integrate time-rate model parameters and reservoir properties. This method avoids the non-uniqueness issues often associated with model-based production data analysis. This study provides theoretical basis for further demonstration of the methodology using field cases. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148425

Unconventional Reservoirs: Rate and Pressure Transient Analysis Techniques

Author : Amin Taghavinejad
Publisher : Springer Nature
ISBN 13 : 3030828379
Total Pages : 119 pages
Book Rating : 4.0/5 (38 download)

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Book Synopsis Unconventional Reservoirs: Rate and Pressure Transient Analysis Techniques by : Amin Taghavinejad

Download or read book Unconventional Reservoirs: Rate and Pressure Transient Analysis Techniques written by Amin Taghavinejad and published by Springer Nature. This book was released on 2021-09-13 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a succinct overview on the application of rate and pressure transient analysis in unconventional petroleum reservoirs. It begins by introducing unconventional reservoirs, including production challenges, and continues to explore the potential benefits of rate and pressure analysis methods. Rate transient analysis (RTA) and pressure transient analysis (PTA) are techniques for evaluating petroleum reservoir properties such as permeability, original hydrocarbon in-place, and hydrocarbon recovery using dynamic data. The brief introduces, describes and classifies both techniques, focusing on the application to shale and tight reservoirs. Authors have used illustrations, schematic views, and mathematical formulations and code programs to clearly explain application of RTA and PTA in complex petroleum systems. This brief is of an interest to academics, reservoir engineers and graduate students.

Applications of Inverse Theory and Machine Learning in Rate/pressure Transient Analysis

Author : Nitinkumar Lalitkumar Chaudhary
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (12 download)

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Book Synopsis Applications of Inverse Theory and Machine Learning in Rate/pressure Transient Analysis by : Nitinkumar Lalitkumar Chaudhary

Download or read book Applications of Inverse Theory and Machine Learning in Rate/pressure Transient Analysis written by Nitinkumar Lalitkumar Chaudhary and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The applicability of decline relations (empirical or analytical) in rate transient analysis (RTA) to forecast the production of an unconventional reservoir depends on the validity of assumptions made during the development of these decline relations. None of the present rate decline relations used to estimate the ultimate recovery (EUR), are conceptually applicable in a reservoir where hydrocarbon production exhibits variable rate and pressure. We propose a new methodology based on an inverse deconvolution problem formulation to accurately forecast performance in such reservoirs. To handle the instability in deconvolution, we propose the use of elastic net regularization and a new weighting scheme in our deconvolution algorithm. In this work, we propose a non-parametric density-based outlier detection method, which identifies outliers by classifying the data into clusters and assigning local outlier factors to the individual data points. We validate our method using synthetic examples generated using numerical models of multi-stage hydraulically fractured wells in unconventional reservoirs. Upon validation we demonstrate our method using field examples. Our work demonstrates that this new methodology integrating, pressures into decline curve analysis is theoretically and practically more robust than the analysis of pressure normalized decline curves currently used to solve the problem.

The Variability of Reservoir Storage Estimates

Author : Richard Mark Vogel
Publisher :
ISBN 13 :
Total Pages : 442 pages
Book Rating : 4.E/5 ( download)

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Book Synopsis The Variability of Reservoir Storage Estimates by : Richard Mark Vogel

Download or read book The Variability of Reservoir Storage Estimates written by Richard Mark Vogel and published by . This book was released on 1985 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Development of Unconventional Reservoirs

Author : Bradley R. Cronk
Publisher :
ISBN 13 :
Total Pages : 136 pages
Book Rating : 4.:/5 (18 download)

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Book Synopsis Development of Unconventional Reservoirs by : Bradley R. Cronk

Download or read book Development of Unconventional Reservoirs written by Bradley R. Cronk and published by . This book was released on 2018 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Application of Function Approximations to Reservoir Engineering

Author : Saber Khaled Elmabrouk
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis Application of Function Approximations to Reservoir Engineering by : Saber Khaled Elmabrouk

Download or read book Application of Function Approximations to Reservoir Engineering written by Saber Khaled Elmabrouk and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Informing the Modified-Hyperbolic Decline Curve0́9s Minimum Decline Parameter with Numerical Simulation in Unconventional Reservoirs

Download Informing the Modified-Hyperbolic Decline Curve0́9s Minimum Decline Parameter with Numerical Simulation in Unconventional Reservoirs PDF Online Free

Author : Zakary Kypfer
Publisher :
ISBN 13 :
Total Pages : 68 pages
Book Rating : 4.5/5 (16 download)

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Book Synopsis Informing the Modified-Hyperbolic Decline Curve0́9s Minimum Decline Parameter with Numerical Simulation in Unconventional Reservoirs by : Zakary Kypfer

Download or read book Informing the Modified-Hyperbolic Decline Curve0́9s Minimum Decline Parameter with Numerical Simulation in Unconventional Reservoirs written by Zakary Kypfer and published by . This book was released on 2021 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: ne of the most important aspects in the life-cycle of a petroleum well is understanding, and being able to reasonably predict, the total hydrocarbon output that a well will have through its producing life. The estimation of reserves has strong economic and legal implications that will not only determine whether a well-drilling plan is viable but also the worth of a company itself. This study aims to better understand the two primary production forecasting methods used in the petroleum industry: decline curve analyses and numerical reservoir simulations, and their ability to complement one another to make a better-informed production forecast when used together. Decline curve analyses have a heavy reliance on prior hydrocarbon production data which presents difficulty in forecasting during early-term behavior due to a lack of production data; however, reservoir simulations are stronger in early well-life because they are based more heavily on reservoir parameters. The objective is to use reservoir simulations to inform the decline curve's early time behavior, by informing parameters in their equations such as Dmin, while developing a correlational relationship between the two forecasting techniques that could be applied and translated to other reservoirs in the future. A decline curve analysis was performed on a three-well study area and Dmin values of 6%, 8%, and 10% were evaluated. The matching process of the decline curves heavily relied on the cumulative production in addition to the production rates, which used a thirty-day rolling average of the daily production data. Two equivalent numerical reservoir simulation models were built for the Eagle Ford which primarily used literature sourced values for the properties. The models were history matched to the observed data very well, though each model indicated different conclusions for a suggested Dmin value. Further compounding the results, the range of uncertainty in the matrix porosity property is larger than the range of the Dmin values. Due to this, the authors are not able to use the simulation models to inform parameters in decline curve analyses nor attempt to translate that relationship to other reservoirs.

A Semi-Analytical Analysis of the Gas and Water Forecasts from Unconventional Reservoirs

Author : Abdulla Saleh Alzaabi
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)

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Book Synopsis A Semi-Analytical Analysis of the Gas and Water Forecasts from Unconventional Reservoirs by : Abdulla Saleh Alzaabi

Download or read book A Semi-Analytical Analysis of the Gas and Water Forecasts from Unconventional Reservoirs written by Abdulla Saleh Alzaabi and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Material balance is an essential reservoir engineering tool that is used to determine original hydrocarbon in place and the production performance of a reservoir. There are several types of material-balance approaches developed, each with its own application. Such approaches include integral material balance, differential material balance and flowing material balance. In this thesis, a form of differential material balance, similar to the one developed by Muskat for Solution Gas Drive Reservoirs, has been derived for unconventional gas-water reservoirs impacted by adsorption. Originally, the developed Muskat-type equation is in the pressure domain, but it can also be derived in other domains such as the time domain and the cumulative produced fluids domains. The resulting system of ordinary differential equations (ODEs) are then solved using fourth order Runge-Kutta method which is a traditional ODE solver. The system of two differential equations for the Muskat-type equation in the time domain (time as an independent variable), are formulated with pressure and water saturation as the dependent variables. These resulting ODEs are then used to forecast and analyze the production profiles of a gas-water reservoir considering adsorption. The semi-analytical model is then validated internally using finite difference and analytical rate derivative equations, and externally by benchmarking it with a numerical simulator. The significant factor that caused the disparity between the semi-analytical model proposed in this study and the numerical simulator is the time it takes to reach pseudo-steady state flow (t_pss) with lower times producing better results. At t_pss less than 0.111 days , numerical simulation is almost replaceable in forecasting rates. However, at t_pss less than 0.717 days, cumulative gas produced can be accurately forecasted. This is to be expected and a reservoir simulator is fully transient, while material balance is based on the pseudo steady-state flow regime. This study provided a unique opportunity to investigate the characteristics of the production profile such as the peak rate and the observed inflection points while also identifying the reservoir parameters that affect them. Moreover, an equation has been developed that can be used to identify and describe the peak rate. This equation makes use of the byproduct of the Muskat-type equation ((dS_w)/dP) which can be modified in terms of rock and fluid properties to aid in history matching. Furthermore, three well specifications were investigated (constant well pressure, constant drawdown, and constant water production rate) with only two of the three producing a peak rate no peak gas production rate was observed for water rate specified wells. This study also showed that material balance can be used to replace decline curve analysis under certain conditions. This is mainly due to the reduced time to pseudo-steady state (t_pss) caused by the low total compressibility (rock and water), high permeability, low water viscosity, and low drainage area. At a threshold of t_pss less than 0.178 days, an accurate late-time forecast can be attained.Since the proposed semi-analytical model provided water saturation values for different pressures, a non-iterative methodology has been developed to improve upon Kings (G. R. King, 1993) iterative integral material balance equation for unconventional reservoirs.Through this study, a number of significant observations were made. It was found that at a low rock compressibility, the change in saturation over time can be estimated using the water production profile and initial porosity and water formation volume factor. Also, the saturation of gas can be estimated using the percentage of water produced from the original water in place (OWIP), adjusted for desorption time, at an increasing accuracy as the rock compressibility is decreased. Additionally, the cause of a phenomenon known as dual peaking which occurs in field and simulation data of CBM reservoirs has been identified to be due to the transient-state production.

Approximate Bayesian Computation for Probabilistic Decline Curve Analysis in Unconventional Reservoirs

Author : Mohit Paryani
Publisher :
ISBN 13 :
Total Pages : 146 pages
Book Rating : 4.:/5 (927 download)

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Book Synopsis Approximate Bayesian Computation for Probabilistic Decline Curve Analysis in Unconventional Reservoirs by : Mohit Paryani

Download or read book Approximate Bayesian Computation for Probabilistic Decline Curve Analysis in Unconventional Reservoirs written by Mohit Paryani and published by . This book was released on 2015 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Predicting the production rate and ultimate production of shale resource plays is critical in order to determine if development is economical. In the absence of production from the Shublik Shale, Alaska, Arps' decline model and other newly proposed decline models were used to analyze production data from oil producing wells in the Eagle Ford Shale, Texas. It was found that shales violated assumptions used in Arps' model for conventional hydrocarbon accumulations. Newly proposed models fit the past production data to varying degrees, with the Logistic Growth Analysis (LGA) and Power Law Exponential (PLE) models making the most conservative predictions and those of Duong's model falling in between LGA and PLE. Using a regression coefficient cutoff of 95%, we see that the LGA model fits the production data (both rate and cumulative) from 81 of the 100 wells analyzed. Arps' hyperbolic and the LGA equation provided the most optimistic and pessimistic reserve estimates, respectively. The second part of this study investigates how the choice of residual function affects the estimation of model parameters and consequent remaining well life and reserves. Results suggest that using logarithmic rate residuals maximized the likelihood of Arps' equation having bounded estimates of reserves. We saw that approximately 75% of the well histories that were fitted using the logarithmic rate residual had hyperbolic b-values

Development of Correlation Functions Using Reservoir Properties and Recovery Mechanisms for Ultimate Recovery

Author : Nestor Orlando Gonzalez P.
Publisher :
ISBN 13 :
Total Pages : 106 pages
Book Rating : 4.:/5 (279 download)

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Book Synopsis Development of Correlation Functions Using Reservoir Properties and Recovery Mechanisms for Ultimate Recovery by : Nestor Orlando Gonzalez P.

Download or read book Development of Correlation Functions Using Reservoir Properties and Recovery Mechanisms for Ultimate Recovery written by Nestor Orlando Gonzalez P. and published by . This book was released on 1977 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Petroleum Reservoir Fluid Property Correlations

Author : William D. McCain
Publisher : Pennwell Books
ISBN 13 : 9781593701871
Total Pages : 0 pages
Book Rating : 4.7/5 (18 download)

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Book Synopsis Petroleum Reservoir Fluid Property Correlations by : William D. McCain

Download or read book Petroleum Reservoir Fluid Property Correlations written by William D. McCain and published by Pennwell Books. This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large sets of petroleum fluid data exist for the various reservoir conditions and properties that occur in practice. Petroleum Reservoir Fluid Property Correlations, written by three internationally well-known and respected petroleum engineers, is the result of several years of exhaustive research that gathered data sets from databases all over the world. The data were compared against the results of many published correlations of fluid properties in order to find the "best in class" required in the petroleum industry. Those findings are offered here as recommended use in reservoir engineering calculations. The data sets cover natural gases, reservoir oils, and reservoir waters (brines). The result of this research project is the best correlation for each fluid property. Key Features: * Best-in-class correlations contained in one volume * The most accurate data for reservoir engineering calculations * Correlations that cover all reservoir hydrocarbons and brines Petroleum Reservoir Fluid Property Correlations will prove to be a valuable resource for reservoir engineers, production engineers who need to determine which set of correlation equations are most useful for their work, and graduate-level reservoir engineering courses.

Validation of a New and Cost Effective Technique to Estimate Reservoir Pressure and Permeability in Low-permeability Reservoirs

Author : Zoha Nasizadeh
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (1 download)

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Book Synopsis Validation of a New and Cost Effective Technique to Estimate Reservoir Pressure and Permeability in Low-permeability Reservoirs by : Zoha Nasizadeh

Download or read book Validation of a New and Cost Effective Technique to Estimate Reservoir Pressure and Permeability in Low-permeability Reservoirs written by Zoha Nasizadeh and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: I developed the mathematical basis for a new and cost effective method to estimate reservoir pressure and effective water permeability in low permeability reservoirs. This method, called Baseline/Calibration, was successfully tested in Wamsutter fields. This approach, which is an alternative to time-consuming DFIT tests and conventional pressure buildup tests, requires injection of water in multiple short stages. Sandface pressure and flow rate are analyzed to estimate reservoir pressure and permeability. I derived analytical expressions which provide a mathematical basis for this method. The analytical formulations are based on transient solutions to the diffusivity equation, the principle of superposition, and assume piston-like displacement of reservoir fluids with injected water. I constructed several numerical simulation models and validated the proposed technique. I also analyzed flow rate and pressure data from two field trials performed in the Almond formation of the Wamsutter field. The results of numerical simulation and field trials of this method verified that our method accurately determines reservoir pressure with short injection tests. Reservoir pressure is a fundamental property of the reservoir and its depletion provides an insight in to the reservoir dynamics and drainage pattern. Measurements of formation pressure and in-situ reservoir permeability are important for a variety of reasons including estimation of ultimate recovery, production forecasting, and optimization of depletion planning. Unconventional gas reservoirs are economically viable hydrocarbon prospects that have proven to be very successful. However, conventional well tests methods are often impractical in unconventional reservoirs. Long shut-in times are required for estimates of reservoir pressure and reservoir permeability.

Three Dimensional Analytical Model for Rate Decline Analysis in Conventional and Unconventional Reservoirs

Author : Umer Farooq
Publisher :
ISBN 13 :
Total Pages : 134 pages
Book Rating : 4.:/5 (11 download)

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Book Synopsis Three Dimensional Analytical Model for Rate Decline Analysis in Conventional and Unconventional Reservoirs by : Umer Farooq

Download or read book Three Dimensional Analytical Model for Rate Decline Analysis in Conventional and Unconventional Reservoirs written by Umer Farooq and published by . This book was released on 2019 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Modeling Small Reservoirs in the Great Plains to Estimate Overflow and Ground-water Recharge

Author : Ravikumar B. Choodegowda
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (656 download)

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Book Synopsis Modeling Small Reservoirs in the Great Plains to Estimate Overflow and Ground-water Recharge by : Ravikumar B. Choodegowda

Download or read book Modeling Small Reservoirs in the Great Plains to Estimate Overflow and Ground-water Recharge written by Ravikumar B. Choodegowda and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Small reservoirs catch and store water for long periods and they decrease streamflow and increase ground-water recharge. A field monitoring program provided the measured water depth for four years in several reservoirs in the Republican River Basin where there are concerns about their aggregate effects in the basin. The daily water budget operation for one reservoir was developed. Daily seepage rates were estimated by using precipitation, inflow and evaporation which was assumed equal to grass reference evapotranspiration (ET0), that average 120 to 150 cm/yr, along with the measured stage-storage and stage-surface area relationships. Two computer simulation modules, written in FORTRAN 95, were developed to estimate 1) overflow and gross seepage and 2) potential for ground-water recharge underneath the reservoir. Required daily input data are precipitation, ET0, and inflow from the watershed area. Required reservoir site characteristics include stage-storage and stage-surface area relationships, a standard seepage rate (S0) at 14 different levels in the reservoir, soil-water and plant-growth characteristics and a monthly crop-residue factor. The gross seepage module calculates water depth that determines daily overflow, the water-surface area for evaporation and the head of water on the 14 levels to cause seepage losses. If a level is not inundated, seepage is zero. If a level is inundated less than 0.3-m, S0 is used. When the water head (hL) on a level exceeds 0.3 m, the seepage rate (SL) is increased by, SL = S0 * (hL/0.3)0.25. This relationship was chosen after testing several exponent values between 0 and 1. The modules were calibrated on one reservoir and verified on two others in northwestern Kansas. Results showed runoff from the watersheds averaged about 1.2 to 1.6 cm/yr from the average annual precipitation of 46 to 62 cm. The three reservoirs reduced streamflow at the reservoir site by 74 to 97%, but 90 to 95% of the retained runoff was calculated to contribute to ground-water recharge. Several sensitivity analyses for model inputs were done. Results showed that, the ratio of the average annual inflow volume from the watershed area to the reservoir storage volume was the most sensitive input variable tested.

Application of Probabilistic Decline Curve Analysis to Unconventional Reservoirs

Author : Uchenna C. Egbe
Publisher :
ISBN 13 :
Total Pages : 126 pages
Book Rating : 4.:/5 (132 download)

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Book Synopsis Application of Probabilistic Decline Curve Analysis to Unconventional Reservoirs by : Uchenna C. Egbe

Download or read book Application of Probabilistic Decline Curve Analysis to Unconventional Reservoirs written by Uchenna C. Egbe and published by . This book was released on 2022 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents the various probabilistic methodology for forecasting petroleum production in shale reservoirs. Two statistical methods are investigated, Bayesian and frequentist, combined with various decline curve deterministic models. A robust analysis of well-completion properties and how they affect the production forecast is carried out. Lastly, a look into the uncertainties introduced by the statistical methods and the decline curve models are investigated to discover any correlation and plays that otherwise would not be apparent. We investigated two Bayesian methods - Absolute Bayesian Computation (ABC) and GIBBS sampler - and two frequentist methods - Conventional Bootstrap (BS) and Modified Bootstrap (MBS). We combined these statistical methods with five empirical models - Arps, Duong, Power Law Model (PLE), Logistic Growth Model (LGA), and Stretched Exponential Decline Model (SEPD) - and an analytical Jacobi 2 theta model. This allowed us to make a robust comparison of all these approaches on various unconventional plays across the United States, including Permian, Marcellus, Eagle Ford, Haynesville, Barnett, and Bakken shale, to get detailed insight on how to forecast production with minimal prediction errors effectively. Analysis was carried out on a total of 1800 wells with varying production history data lengths ranging from 12 to 60 months on a 12-month increment and a total production length of 96 months. We developed a novel approach for developing and integrating informative model parameter priors into the Bayesian statistical methods. Previous work assumed a uniform distribution for model parameter priors, which was inaccurate and negatively impacted forecasting performance. Our results show the significant superior performance of the Bayesian methods, most notably at early hindcast size (12 to 24 months production history). Furthermore, we discovered that production history length was the most critical factor in production forecasting that leveled the performance of all probabilistic methods regardless of the decline curve model or statistical methodology implemented. The novelty of this work relies on the development of informative priors for the Bayesian methodologies and the robust combination of statistical methods and model combination studied on a wide variety of shale plays. In addition, the whole methodology was automated in a programming language and can be easily reproduced and used to make production forecasts accurately.

Probabilistic Decline Curve Analysis in Unconventional Reservoirs Using Bayesian and Approximate Bayesian Inference

Author : Anand A. Korde
Publisher :
ISBN 13 :
Total Pages : 170 pages
Book Rating : 4.:/5 (111 download)

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Book Synopsis Probabilistic Decline Curve Analysis in Unconventional Reservoirs Using Bayesian and Approximate Bayesian Inference by : Anand A. Korde

Download or read book Probabilistic Decline Curve Analysis in Unconventional Reservoirs Using Bayesian and Approximate Bayesian Inference written by Anand A. Korde and published by . This book was released on 2019 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, a probabilistic methodology for Decline Curve Analysis (DCA) in unconventional reservoirs is presented using a combination of Bayesian statistical methods and deterministic models. Accurate reserve estimation and uncertainty quantification are the primary objectives of this study. The Bayesian inferencing techniques described in this work utilizes three sampling mechanisms, namely the Gibbs Sampling (implemented in OpenBUGS), the Metropolis Algorithm, and Approximate Bayesian Computation (ABC) to sample parameter values from their posterior distributions. These different sampling mechanisms are applied in conjunction with DCA models like Arps, Power Law Exponential (PLE), Stretched Exponential Production Decline (SEPD), Duong and Logistic Growth Analysis (LGA) to estimate prediction intervals. Production is forecasted, and uncertainty bounds are established using these prediction intervals. A complete workflow and the summary steps for each of the sampling techniques are provided to permit readers to replicate results. To examine the reliability, the methodology was tested over 74 oil and gas wells located in the three main sub plays of the Permian Basin, namely, the Delaware play, the Central Basin Platform, and the Midland play. Results show that the examined DCA-Bayesian models are successful in providing a high coverage rate, low production prediction errors and narrow uncertainty bounds for the production history data sets. The methodology was also successfully applied to unconventional reservoirs with as low as 6 months of available production history. Depending on the amount of production history available, the combined deterministic-stochastic model that provides the best fit can vary. It is therefore recommended that all possible combinations of the deterministic and stochastic models be applied to the available production history data. This is in order to obtain more confidence in the conclusions related to the reserve estimates and uncertainty bounds. The novelty of this methodology relies in using multiple combinations of DCA-Bayesian models to achieve accurate reserve estimates and narrow uncertainty bounds. The paper can help assess shale plays as most of the shale plays are in the early stages of production when the reserve estimations are carried out.

A Novel Approach for the Rapid Estimation of Drainage Volume, Pressure and Well Rates

Author : Neha Gupta
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (865 download)

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Book Synopsis A Novel Approach for the Rapid Estimation of Drainage Volume, Pressure and Well Rates by : Neha Gupta

Download or read book A Novel Approach for the Rapid Estimation of Drainage Volume, Pressure and Well Rates written by Neha Gupta and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For effective reservoir management and production optimization, it is important to understand drained volumes, pressure depletion and reservoir well rates at all flow times. For conventional reservoirs, this behavior is based on the concepts of reservoir pressure and energy and convective flow. But, with the development of unconventional reservoirs, there is increased focus on the unsteady state transient flow behavior. For analyzing such flow behaviors, well test analysis concepts are commonly applied, based on the analytical solutions of the diffusivity equation. In this thesis, we have proposed a novel methodology for estimating the drainage volumes and utilizing it to obtain the pressure and flux at any location in the reservoir. The result is a semi-analytic calculation only, with close to the simplicity of an analytic approach, but with significantly more generality. The approach is significantly faster than a conventional finite difference solution, although with some simplifying assumptions. The proposed solution is generalized to handle heterogeneous reservoirs, complex well geometries and bounded and semi-bounded reservoirs. Therefore, this approach is particularly beneficial for unconventional reservoir development with multiple transverse fractured horizontal wells, where limited analytical solutions are available. To estimate the drainage volume, we have applied an asymptotic solution to the diffusivity equation and determined the diffusive time of flight distribution. For the pressure solution, a geometric approximation has been applied within the drainage volume to reduce the full solution of the diffusivity equation to a system of decoupled ordinary differential equations. Besides, this asymptotic expression can also be extended to obtain the well rates, producing under constant bottomhole pressure constraint. In this thesis, we have described the detailed methodology and its validation through various case studies. We have also studied the limits of validity of the approximation to better understand the general applicability. We expect that this approach will enable the inversion of field performance data for improved well and/or fracture characterization, and similarly, the optimization of well trajectories and fracture design, in an analogous manner to how rapid but approximate streamline techniques have been used for improved conventional reservoir management. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148380