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Christopher R. Clarkson - One of the best experts on this subject based on the ideXlab platform.
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Production data analysis of tight gas condensate reservoirs
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Hamid Behmanesh, Hamidreza Hamdi, Christopher R. ClarksonAbstract:Abstract The current focus on liquids-rich shale (LRS) plays in North America underscores the need to develop reservoir engineering methods to analyze such reservoirs. Commercialization of LRS plays is now possible due to new technology, such as multi-fractured horizontal wells (MFHW). Efficient production from such reservoirs necessitates understanding of flow mechanisms, reservoir properties and the controlling rock and fluid parameters. Production-decline analysis is an important technique for analysis of production data and obtaining estimates of recoverable reserves. Nevertheless, these techniques, developed for conventional reservoirs, are not appropriate for ultra-low permeability reservoirs. There are substantial differences in reservoir performance characteristics between conventional and ultra-low permeability reservoirs. LRS reservoirs produce much leaner wellstreams compared to conventional reservoirs due to very low permeabilities that result in very large drawdowns. Methods for analysis of two-phase flow in conventional reservoirs, with underlying simplifying assumptions, are no longer applicable. This paper discusses production data analysis of constant flowing bottomhole pressure (FBHP) wells producing from LRS (gas condensate) reservoirs. A theoretical basis is developed for a gas condensate reservoir during the transient matrix linear flow (drawdown) period. The governing flow equation is linearized using appropriately defined two-phase Pseudopressure and pseudotime functions so that the solutions for liquids can be applied. The derived backward model is employed to compute the linear flow parameter, x f √ k . Simulation results show that the liquid yield will be approximately constant for LRS wells during the transient linear flow, from the early days of initial testing, if FBHP is almost constant. An analytical formulation is used to prove this finding for 1D transient linear flow of LRS wells. The proposed production data analysis (PDA) method is illustrated using simulated production data for different fluid models and relative permeability curves. Fine-grid compositional and black oil numerical models are used for this purpose.
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Estimation of Unconventional Reservoir Matrix Permeability and Pore Volume Using Rate-Transient Analysis Techniques: Method Refinements
Sixth EAGE Shale Workshop, 2019Co-Authors: Christopher R. Clarkson, A. Vahedian, A. Ghanizadeh, Chengyao SongAbstract:A core analysis procedure based on rate-transient analysis theory has been successfully tested in the lab. Two permeability estimates and one pore volume estimate are possible using this technique, with the results being achieved faster than conventional testing (e.g. pulse-decay test). Refinements in one permeability estimation method, based on the distance of investigation, were illustrated. The combination of the rate-normalized Pseudopressure derivative, used to identify the end of linear flow, and a new expression for DOI, yielded permeability values very close to the pulse-decay method.
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Analytical modeling of linear flow in single-phase tight oil and tight gas reservoirs
Journal of Petroleum Science and Engineering, 2018Co-Authors: Hamid Behmanesh, Hamidreza Hamdi, Christopher R. Clarkson, John M. Thompson, David AndersonAbstract:Abstract Unconventional reservoirs, including tight oil, tight gas and shale gas are economically attractive, but operationally challenging, particularly for cases when complex flow behavior occurs within the reservoir. Accounting for the physics of flow in such formations is central to providing improved short- and long-term oil and gas production forecasts. At the early phase of development of these reservoirs, and in the presence of limited data, analytical models are more suited for mechanistic studies leading to improved understanding of the reservoir. Analytical models often utilize solutions to flow equations for liquids with constant viscosity, and small and constant compressibility. In tight formations, however, these assumptions simply do not apply as fluid and rock properties change with pressure drawdown. Historically, efforts have concentrated on linearizing the governing partial-differential equations to account for these effects by employing appropriately defined Pseudopressure and pseudotime functions. A rigorous approach for determination of pseudotime includes the use of average pressure in the distance of investigation during transient flow. In this work, an analytical expression for average reservoir pressure in the (dynamic) drainage area is derived for constant pressure and constant rate production scenarios. By deriving an explicit relation for average pressure in the drainage area as a function of the initial reservoir pressure and the wellbore pressure, the iterative procedure for calculation of pseudotime is relaxed. Using the developed expression for average pressure in the distance of investigation, the pseudo steady-state deliverability equation is extended to model the transient period by incorporating the dynamic drainage area concept in the productivity index equation. We first verify the applicability of the developed approach for oil reservoirs and later demonstrate that the approach is considered to be useful for analysis of production data from tight gas reservoirs. The established methodology in this work provides a useful tool for rapid forecasting of tight oil and tight gas wells, allowing for the examination of the effects of different parameters on the forecast.
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Transient linear flow analysis of constant-pressure wells with finite conductivity hydraulic fractures in tight/shale reservoirs
Journal of Petroleum Science and Engineering, 2015Co-Authors: M. Heidari Sureshjani, Christopher R. ClarksonAbstract:Abstract Transient linear flow is the dominant flow regime in many multi-fractured horizontal wells completed in very low permeability reservoirs. Therefore, development of reliable methods for analyzing production data from this flow regime is of great value. The common methodology for production analysis of this flow period is use of square-root-time plot in which normalized pressure (or Pseudopressure for gas) is plotted vs. square-root-time. This method has been proved to be acceptable for systems with infinite conductivity hydraulic fractures. The square-root-time plots for such systems exhibit a zero intercept. When analyzing production histories of real examples, we observe cases for which the square-root-time plot exhibits a straight-line trend with a positive intercept. We demonstrate that this behavior can be attributed to systems with finite conductivity hydraulic fractures. For constant-pressure systems with finite conductivity hydraulic fractures, the square-root-time plot methodology overestimates fracture half-length. This has been shown using synthetic examples. To solve this problem, we have developed a new inverse solution methodology which is based on an analytical formulation. We have defined new plotting functions and illustrated that a plot of these functions against each other in the formation linear flow period exhibits a linear trend. From the slope of this plot, the true value of fracture half-length can be estimated. Also, fracture conductivity can be determined from the intercept. The proposed methodology has been verified using synthetic tight oil examples. We have also applied it for several tight gas examples. We have analyzed production data for two field examples using the conventional square-root-time plot methodology and the new inverse solution methodology. Our analysis reveals that the square-root-time plot methodology considerably overestimates the fracture half-length for these examples.
Shahab Gerami - One of the best experts on this subject based on the ideXlab platform.
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A new approach for analysis of production data from constant production rate wells in gas condensate reservoirs
Journal of Natural Gas Science and Engineering, 2014Co-Authors: Milad Arabloo, Mohammadhossein Heidari Sureshjani, Shahab GeramiAbstract:Abstract Production data analysis provides key parameters to a series of reservoir engineering calculations such as reserve estimation, inflow performance calculations, and well production forecast. Although techniques of production data analysis for oil and dry gas reservoirs have advanced significantly over the past few decades, application of these techniques for analyzing production data of gas condensate reservoirs has not been fully studied despite its great practical importance. In this work, a simple yet accurate methodology is presented for reliable estimation of initial gas in place and average reservoir pressure in gas condensate reservoirs. We define new Pseudopressure and material balance time functions suitable for gas condensate systems. According to our observations, a Cartesian plot of modified normalized Pseudopressure versus modified material balance pseudotime of gas condensate production data yields three distinct regions. In this study we will show that the middle region is unusable and should be distinguished and removed from the analysis. The required input data are bottom hole flowing pressures, gas and condensate production rates, and constant volume depletion (CVD) test data. This study provides example analyses and establishes guidelines for the analysis and interpretation of long term production data in gas condensate reservoirs using developed Cartesian plot.
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Explicit Rate–Time Solutions for Modeling Matrix–Fracture Flow of Single Phase Gas in Dual-Porosity Media
Transport in Porous Media, 2012Co-Authors: Mohammadhossein Heidari Sureshjani, Shahab Gerami, Mohammad Ali EmadiAbstract:One of the widely used methods for modeling matrix–fracture fluid exchange in naturally fractured reservoirs is dual porosity approach. In this type of modeling, matrix blocks are regarded as sources/sinks in the fracture network medium. The rate of fluid transfer from matrix blocks into fracture medium may be modeled using shape factor concept (Warren and Root, SPEJ 3:245–255, 1963 ); or the rate–time solution is directly derived for the specific matrix geometry (de Swaan, SPEJ 16:117–122, 1976 ). Numerous works have been conducted to study matrix–fracture fluid exchange for slightly compressible fluids (e.g. oil). However, little attention has been taken to systems containing gas (compressible fluid). The objective of this work is to develop explicit rate–time solutions for matrix–fracture fluid transfer in systems containing single phase gas. For this purpose, the governing equation describing flow of gas from matrix block into fracture system is linearized using Pseudopressure and pseudotime functions. Then, the governing equation is solved under specific boundary conditions to obtain an implicit relation between rate and time. Since rate calculations using such an implicit relation need iterations, which may be computationally inconvenient, an explicit rate–time relation is developed with the aid of material balance equation and several specific assumptions. Also, expressions are derived for average Pseudopressure in matrix block. Furthermore, simplified solutions (originated from the complex general solutions) are introduced applicable in infinite and finite acting flow periods in matrix. Based on the derived solutions, expressions are developed for shape factor. An important observation is that the shape factor for gas systems is the same as that of oil bearing matrix blocks. Subsequently, a multiplier is introduced which relates rate to matrix pressure instead of matrix Pseudopressure. Finally, the introduced equations are verified using a numerical simulator.
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A New Model for Modern Production-Decline Analysis of Gas/Condensate Reservoirs
Journal of Canadian Petroleum Technology, 2011Co-Authors: M. Heidari Sureshjani, Shahab GeramiAbstract:Modern production-decline analysis is a robust technique for analysis of production data from a well under variable operating conditions. It uses production rates and flowing pressures to provide reliable estimates of recoverable reserves and fluid in place. The mathematics behind this technique is similar to that of pressure-transient theory; however, the focus is different. It deals with long-term variable production data instead of short-term constant-rate transient data. Using modern decline analysis for two-phase-flow conditions (e.g., gas/condensate reservoirs) is under question because of the single-phase-flow assumption in the development of the "material-balance time" function. This is a time function that converts any decline (e.g., exponential decline) to harmonic decline to account for variable operating conditions. The purpose of this work is to develop a model to use the concepts of modern techniques for analyzing production data of single-porosity gas/condensate reservoirs. For this purpose, the governing flow equation is linearized, using appropriately defined Pseudopressure and pseudotime functions. Then, the solution is obtained for constant-well-rate condition. This is followed by employing the superposition theorem to account for variable well pressure/rate conditions, resulting in definition of two-phase material-balance pseudotime. The solution developed here is coupled with an appropriate material-balance equation and used to estimate the average reservoir pressure and original gas in place from analyzing production data. The dependency of relative permeability on capillary number and non-Darcy flow is included in the formulation. Verification of the proposed method is obtained with the analysis of synthetic production data using a series of fine-grid compositional numerical simulations over a typical range of gas/ condensate-reservoir parameters.
Hamid Behmanesh - One of the best experts on this subject based on the ideXlab platform.
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Production data analysis of tight gas condensate reservoirs
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Hamid Behmanesh, Hamidreza Hamdi, Christopher R. ClarksonAbstract:Abstract The current focus on liquids-rich shale (LRS) plays in North America underscores the need to develop reservoir engineering methods to analyze such reservoirs. Commercialization of LRS plays is now possible due to new technology, such as multi-fractured horizontal wells (MFHW). Efficient production from such reservoirs necessitates understanding of flow mechanisms, reservoir properties and the controlling rock and fluid parameters. Production-decline analysis is an important technique for analysis of production data and obtaining estimates of recoverable reserves. Nevertheless, these techniques, developed for conventional reservoirs, are not appropriate for ultra-low permeability reservoirs. There are substantial differences in reservoir performance characteristics between conventional and ultra-low permeability reservoirs. LRS reservoirs produce much leaner wellstreams compared to conventional reservoirs due to very low permeabilities that result in very large drawdowns. Methods for analysis of two-phase flow in conventional reservoirs, with underlying simplifying assumptions, are no longer applicable. This paper discusses production data analysis of constant flowing bottomhole pressure (FBHP) wells producing from LRS (gas condensate) reservoirs. A theoretical basis is developed for a gas condensate reservoir during the transient matrix linear flow (drawdown) period. The governing flow equation is linearized using appropriately defined two-phase Pseudopressure and pseudotime functions so that the solutions for liquids can be applied. The derived backward model is employed to compute the linear flow parameter, x f √ k . Simulation results show that the liquid yield will be approximately constant for LRS wells during the transient linear flow, from the early days of initial testing, if FBHP is almost constant. An analytical formulation is used to prove this finding for 1D transient linear flow of LRS wells. The proposed production data analysis (PDA) method is illustrated using simulated production data for different fluid models and relative permeability curves. Fine-grid compositional and black oil numerical models are used for this purpose.
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Analytical modeling of linear flow in single-phase tight oil and tight gas reservoirs
Journal of Petroleum Science and Engineering, 2018Co-Authors: Hamid Behmanesh, Hamidreza Hamdi, Christopher R. Clarkson, John M. Thompson, David AndersonAbstract:Abstract Unconventional reservoirs, including tight oil, tight gas and shale gas are economically attractive, but operationally challenging, particularly for cases when complex flow behavior occurs within the reservoir. Accounting for the physics of flow in such formations is central to providing improved short- and long-term oil and gas production forecasts. At the early phase of development of these reservoirs, and in the presence of limited data, analytical models are more suited for mechanistic studies leading to improved understanding of the reservoir. Analytical models often utilize solutions to flow equations for liquids with constant viscosity, and small and constant compressibility. In tight formations, however, these assumptions simply do not apply as fluid and rock properties change with pressure drawdown. Historically, efforts have concentrated on linearizing the governing partial-differential equations to account for these effects by employing appropriately defined Pseudopressure and pseudotime functions. A rigorous approach for determination of pseudotime includes the use of average pressure in the distance of investigation during transient flow. In this work, an analytical expression for average reservoir pressure in the (dynamic) drainage area is derived for constant pressure and constant rate production scenarios. By deriving an explicit relation for average pressure in the drainage area as a function of the initial reservoir pressure and the wellbore pressure, the iterative procedure for calculation of pseudotime is relaxed. Using the developed expression for average pressure in the distance of investigation, the pseudo steady-state deliverability equation is extended to model the transient period by incorporating the dynamic drainage area concept in the productivity index equation. We first verify the applicability of the developed approach for oil reservoirs and later demonstrate that the approach is considered to be useful for analysis of production data from tight gas reservoirs. The established methodology in this work provides a useful tool for rapid forecasting of tight oil and tight gas wells, allowing for the examination of the effects of different parameters on the forecast.
Feridun Esmaeilzadeh - One of the best experts on this subject based on the ideXlab platform.
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a new fast technique for calculation of gas condensate well productivity by using Pseudopressure method
Journal of Natural Gas Science and Engineering, 2012Co-Authors: Mohammad Bonyadi, M R Rahimpour, Feridun EsmaeilzadehAbstract:Abstract This paper presents a new fast technique to obtain gas condensate well productivity without using simulator. The calculation uses a material balance model for reservoir depletion and Fevang and Whitson’s two phase Pseudopressure function for well inflow performance. The two phase Pseudopressure technique cannot be applied independently for well performance evaluation since it requires the well production gas-oil ratio (GOR) as an input. Mott proposed a new method to generate a well’s production GOR by modeling the growth of the condensate banking (Region 1) without using a reservoir simulator. Also, Xiao and AL-Muraikhi described another way to generate well’s production GOR. In this work, an iterative method described to obtain the GOR for each reservoir pressure. High gas velocity impacts such as non-Darcy flow and high capillary number effects can be incorporated into the method. The proposed method has been tested by comparison with the results of fine-grid compositional simulation data in the literature and there is a reasonable agreement between the result of fine-grid simulation and the prediction from the proposed method. The new technique together with Mott’s and Xiao and AL-Muraikhi’s methods is used to obtain the productivity of a gas condensate well in a real field in Iran here referred to as SA4. Also, Genetic Algorithm is used for the optimization of history matching parameters from the toolbox MATLAB software. The results of the calculation show that, different methods of predicting GOR are adequate for quick estimation of gas condensate well productivity without using a simulator, but the new technique overlay is simpler and has a lesser error than the other methods.
W. Sung - One of the best experts on this subject based on the ideXlab platform.
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A new sorption-corrected deconvolution method for production data analysis in a shale gas reservoir containing adsorbed gas
International Journal of Oil Gas and Coal Technology, 2020Co-Authors: Y. Jang, H. Seomoon, W. SungAbstract:When characterising a reservoir with the production data acquired from a shale gas well, the rate-normalised pressure (RNP) method is widely used due to its simplicity. However, for sharply varying production data, such as production and shut-in of a well, the RNP method yields erroneous reservoir characteristics. On the other hand, the deconvolution method can overcome these limitations, but it is only applicable for linear pressure-rate relationships. That is, it is not appropriate for production data acquired from a reservoir containing adsorbed gas. This production data shows nonlinear pressure-rate relationship due to the compressibility of desorbed gas, which strongly influenced by the pressure. In this study, in order to utilise the deconvolution method to analyse sharply varying production data containing adsorbed gas in a shale gas reservoir, we propose the linearised relationship of the sorption-corrected Pseudopressure and production rate by using a variable substitution method such that it can be correctly implemented for deconvolution. From the results of sorption-corrected deconvolution method, we conduct pressure transient analysis for obtaining shale gas reservoir characteristics. [Received: August 18, 2016; Accepted: January 28, 2017]
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The Analysis of Shale Gas Reservoir with Deconvolution Method
79th EAGE Conference and Exhibition 2017, 2017Co-Authors: H. Seomoon, W. SungAbstract:In analyzing the production data obtained from shale gas reservoir, the rate-normalized pressure (RNP) method has been widely used in shale gas industry due to its simplicity. However, for sharply varying production caused from production and shut-in of the well, and for pressure-interfered production data, RNP method gives erroneous results in evaluation the reservoir characteristics. Meanwhile, deconvolution method can overcome the limit of RNP method for sharply varying production data. However, because the deconvolution method is only applicable to linear relationship in pressure-rate data, it is not possible to analyze the production data obtained from coal seam or shale gas reservoir containing sorption characteristics. This production data shows nonlinear relationship in pressure-rate data due to the compressibility of desorbed gas which is strong function of pressure. In this study, the deconvolution method implemented with the sorption-corrected Pseudopressure was proposed for being able to analyze not only sharply varying production data but also pressure-interfered data acquired from multiwell containing sorption characteristics. In this aspect, the sorption-corrected Pseudopressure was derived from material balance equation for linearizing the pressure-rate relationship through a variable substitution method.
