Production Patterns of Eagle Ford Shale Gas: Decline Curve Analysis Using 1084 Wells (original) (raw)
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Characteristic Production Decline Patterns for Shale Gas Wells in Barnett
This paper derives characteristic decline patterns for shale gas wells by analyzing historical well production data using decline curve analysis of 14,453 shale gas wells in the Barnett shale play from 2000 to 2014. The Hyperbolic model and the Stretched Exponential model are applied on the well-by-well production data at average aggregate well and individual well levels to derive the characteristic parameters. Both the Hyperbolic curve and the Stretched Exponential curve display a good fit to the data for both the average aggregate and the individual shale gas wells. The Hyperbolic model performs slightly better than the Stretched Exponential model in this study. The first year rate of decline for production of a shale gas well is around 60% and over the first two years is around 73%. There is an increasing trend in initial production for new wells over the last decade. A supposed cutoff production rate of 133 Mcf/d results in the estimated ultimate recoverable resource (URR) of about 1.4-2.7 billion cubic feet and a well life time of 11-29 years, which is in line with other studies.
Shale gas production decline trend over time in the Barnett Shale
Journal of Petroleum Science and Engineering, 2018
Natural gas produced from shale formations in the United States over the past decade have altered the oil and gas industry remarkably. The Barnett shale was at the forefront of the shale gas revolution in the United States and was considered to be the highest producing natural gas field in the United States until 2012, yielding the top producer spot to the Marcellus shale. Due to the uncertainty regarding the accurate determination of Estimated Ultimate Recoverable (EUR) in shale gas reservoirs, this paper aims to assess EUR values for the Barnett shale using empirical decline curve methods like the Arp's hyperbolic, Modified Arp's hyperbolic and Doung's method. In addition, we investigated the economic viability of wells over time in the Barnett under various probabilities of success. Throughout this paper, reference is made to two key publications where a similar work was carried out for various shale plays in the United States, including the Barnett shale-though only the Arp's hyperbolic decline was employed. The dataset in this paper consisted of more horizontal wells from covering more counties within the Barnett shale compared to other similar studies. We conclude that either the Arp's hyperbolic or Doung's method can be used to forecast EUR in the Barnett shale as only marginal differences were observed. This is on the basis that production history exceeds 10 months (a maximum of 80 months production history was used). We also obtained reliable and conservative estimates of EUR compared to previous studies.
Production Decline Curves of Tight Oil Wells in Eagle Ford Shale
This study derives typical production curves of tight oil wells based on monthly production data from multiple horizontal Eagle Ford shale oil wells. 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 hyperbolic and the stretched exponential function. Individual well productivity, which can be described by IP level, production decline curvature and well lifetime, varies significantly. The average monthly IP was found to be around 500 bbl/day, which yields an EUR in the range of 150– 290 kbbl depending on used curve, assumed well lifetime or production cutoff level. More detailed analyses on EUR can be made once longer time series are available. For more realistic modeling of multiple wells a probabilistic approach might be favorable to account for variety in well productivity. For less detailed modeling, for example conceptual regional bottom-up production modeling, the hyperbolic function with deterministic parameters might be preferred because of ease of use, for example with the average parameter values IP = 500 bbl/day, D = 0.3 and b = 1 resulting in an EUR of 250 kbbl with a 30-year well lifetime, however, with the recognition that this extrapolation is uncertain.
Analysis of Production Data from Horizontal Shale Wells Using Decline Curves
Recent interest in the exploitation of Marcellus shale play, using horizontal drilling and multistage hydraulic fracturing, has increased the demand for reliable estimation of recoverable reserves from ultra-low permeability shale gas formations. Due to the limited field experience, the production performances of Marcellus shale gas reservoirs as well as the key parameters that affect the long-term production of the horizontal wells have not been well-established. Among all the prediction methods, only the Decline Curve Analysis (DCA) technique has proved successful in forecasting production data rapidly and to a high degree of accuracy. Several DCA models including conventional Arps, PLE, and Duong have been utilized in this study to determine the most appropriate method for production data from horizontal Marcellus shale wells. Fekete (Fast Evolution) simulator has been used to generate the thirty year production data from 3000 feet of horizontal lateral. The two base scenarios include seven and thirteen hydraulic fracture stages. The gas adsorbed to shale is also considered. The applicability of several DCA models to shale gas production history was examined using the simulated production profiles. The impact of the permeability, fracture half length, and matrix porosity on DCA models constants were also investigated. Finally, the proposed ratio methodology was applied to the limited production profile (3.5 years of production history) from a well in Upshur County, WV to estimate the DCA constants, and predict the long-term production performance. The prediction results from DCA models then compared to the history-matched simulation model predictions for confirmation.
Geofluids, 2021
This study developed a production-forecasting model to replace the numerical simulation and the decline curve analysis using reservoir and hydraulic fracture data in Montney shale gas reservoir, Canada. A shale-gas production curve can be generated if some of the decline parameters such as a peak rate, a decline rate, and a decline exponent are properly estimated based on reservoir and hydraulic fracturing parameters. The production-forecasting model was developed to estimate five decline parameters of a modified hyperbolic decline by using significant reservoir and hydraulic fracture parameters which are derived through the simulation experiments designed by design of experiments and statistical analysis: (1) initial peak rate ( P hyp ), (2) hyperbolic decline rate ( D hyp ), (3) hyperbolic decline exponent ( b hyp ), (4) transition time ( T transition ), and (5) exponential decline rate ( D exp ). Total eight reservoir and hydraulic fracture parameters were selected as significant...
Energies
This study examined the relationship between the early production data and the long-term performance of shale gas wells, including the estimated ultimate recovery (EUR) and economics. The investigated early production data are peak gas production rate, 3-, 6-, 12-, 18-, and 24-month cumulative gas production (CGP). Based on production data analysis of 485 reservoir simulation datasets, CGP at 12 months (CGP_12m) was selected as a key input parameter to predict a long-term shale gas well’s performance in terms of the EUR and net present value (NPV) for a given well. The developed prediction models were then validated using the field production data from 164 wells which have more than 10 years of production history in Barnett Shale, USA. The validation results showed strong correlations between the predicted data and field data. This suggests that the proposed models can predict the shale gas production and economics reliably in Barnett shale area. Only a short history of production (...
Analysing gas well production data using a simplified decline curve analysis method
Decline curves are one of the most extensively used forms of data analysis employed in evaluating gas reserves and predicting future production. The parameters determined from the classical fit of historical data can be used to predict future production and the most popular and widely accepted method is Arp's equation. In the present work, simpleto-use method, which is easier than existing approaches, less complicated with fewer calculations, is formulated to arrive at an appropriate estimation of nominal (initial) decline rate, and the Arp's decline-curve exponent. The results can be used in follow-up calculations for analysis of past trends of decline in production performance for gas wells as well as reservoirs. Using this method is quite simple and accurate to generate the coefficients of the equations instead of opting for ready-generated coefficients with uncertainty. The engineers can easily develop their own computer program to compute the coefficients and hence obtain the solution for gas reserves and production performance in reservoirs.
Production Decline Analysis and Forecasting in tight-gas reservoirs Lead author Mujeeb Mahadik
Exponential decline curve analysis is widely used to estimate recoverable reserves due to its simplicity. In most cases, however, an exponential model cannot provide a satisfactory match of overall production history. The generalised form of a hyperbolic decline model is more powerful in matching production history than the other decline models, but it is difficult to apply in practical production data analysis since it requires predicting two unknowns as decline constants. Although a hyperbolic model may provide a good fit to early-time production decline data; it may overestimate the late-time production, especially for hydraulic fractured wells in a tight-gas reservoir. In fact, the exponential decline model might be more reliable for forecasting the late-time production.
A Critical Review of Shale Gas Production Analysis and Forecast Methods
2018
DOI: 10.21276/sjeat.2018.3.5.5 Abstract: This paper critically reviews methods applied in forecasting production of unconventional gas plays. The review focuses on methodologies suitable for shale gas plays, methodological ability to account for parameter and data uncertainty, as well as suitability for appraising undeveloped shale gas plays. The production analysis and forecast methods reviewed include empirical/decline curves, type curves and analytical/numerical methods applicable to unconventional gas production analysis and forecast. The review shows that most of the studies focus on developed shale gas plays, neither account for shale gas well reservoir heterogeneity nor account for below ground uncertainties-such as reservoir and source rock properties. This study concludes that significant research is needed to address the identified limitations of existing studies.
Assessment of Eagle Ford Shale Oil and Gas Resources
SPE Unconventional Resources Conference Canada, 2013
The Eagle Ford play in south Texas is currently one of the hottest plays in the United States. In 2012, the average Eagle Ford rig count (269 rigs) was 15% of the total US rig count. Assessment of Eagle Ford oil and gas resources and their associated uncertainties in the early stages is critical for optimal development. The objective of our research was to assess Eagle Ford shale oil and gas reserves, contingent resources, and prospective resources. Probabilistic decline curves using Markov Chain Monte Carlo (MCMC) were used to forecast reserves and resources. The Eagle Ford play from the Sligo Shelf Margin to the San Marcos Arch was divided into 8 different production regions based on geology, fluid type, and well performance. We used the Duong model switching to the Arps model with b = 0.3 at the minimum decline rate to model the linear flow to boundary-dominated flow behavior often observed in shale plays. Cumulative production after 20 years predicted from Monte Carlo simulation...