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Luis F. Ayala - One of the best experts on this subject based on the ideXlab platform.

  • Application of Superposition Principle to Variable Rate/Pressure Production Analysis of Multi-Fractured Horizontal Wells in Unconventional Gas Reservoirs
    Journal of Natural Gas Science and Engineering, 2019
    Co-Authors: Miao Zhang, Luis F. Ayala
    Abstract:

    Abstract Application of superposition principle to non-linear gas governing Equations has been an elusive goal in early-transient production data analysis and has been so far limited to the use of empirical and approximate methods best applicable to boundary-dominated flow conditions. This paper presents a novel and rigorous semi-analytical model that is applicable for the analysis of production data from multi-fractured horizontal gas wells (MFHWs) producing under early-transient variable rate/pressure production conditions. Nonlinear, pressure-dependent hydraulic Diffusivity retained in pseudo-pressure-based gas Diffusivity Equation is straightforwardly and rigorously captured without approximation. The resulting formulation of superposition applied in nonlinear gas system is written in terms of the classical solution for the governing linear partial differential Equation (PDE) plus an analytical adjustment factor that quantifies the nonlinearity of the system. Numerical examples and field cases are presented to test the validity and showcase the capabilities of proposed approach. Comparisons against available empirical and approximate models are also provided for these cases.

  • application of superposition principle to variable rate pressure production analysis of multi fractured horizontal wells in unconventional gas reservoirs
    Journal of Natural Gas Science and Engineering, 2019
    Co-Authors: Miao Zhang, Luis F. Ayala
    Abstract:

    Abstract Application of superposition principle to non-linear gas governing Equations has been an elusive goal in early-transient production data analysis and has been so far limited to the use of empirical and approximate methods best applicable to boundary-dominated flow conditions. This paper presents a novel and rigorous semi-analytical model that is applicable for the analysis of production data from multi-fractured horizontal gas wells (MFHWs) producing under early-transient variable rate/pressure production conditions. Nonlinear, pressure-dependent hydraulic Diffusivity retained in pseudo-pressure-based gas Diffusivity Equation is straightforwardly and rigorously captured without approximation. The resulting formulation of superposition applied in nonlinear gas system is written in terms of the classical solution for the governing linear partial differential Equation (PDE) plus an analytical adjustment factor that quantifies the nonlinearity of the system. Numerical examples and field cases are presented to test the validity and showcase the capabilities of proposed approach. Comparisons against available empirical and approximate models are also provided for these cases.

  • variable rate and pressure integral solutions to the nonlinear gas Diffusivity Equation in unconventional systems
    Fuel, 2019
    Co-Authors: Miao Zhang, Luis F. Ayala
    Abstract:

    Abstract Unconventional gas resources, including tight gas and shale gas, are becoming major sources of natural gas production in U.S. Commercial production from tight or ultra-tight formations requires horizontal wells and massive hydraulic fracturing treatment. These multi-fractured horizontal wells (MFHWs) can exhibit long-term (typically years) early-transient behavior prior to pressure transient reaching the reservoir boundary. Analytical models that have been traditionally developed for transient flow in conventional gas reservoirs face significant challenges when applied to unconventional tight and shale gas, particularly when variable-rate and variable-pressure data needs to be analyzed. This paper presents a rigorous and direct semi-analytical integral solution to the governing nonlinear gas Diffusivity Equations that are directly applicable to realistic unconventional production scenarios of MFHWs. The validity of proposed solution is verified by matching against numerical simulation results using synthetic case studies for both constant and varying rate production conditions. Its applicability to real-life production scenarios is showcased by a field case study using production data from a MFHW in Marcellus Shale.

Miao Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Application of Superposition Principle to Variable Rate/Pressure Production Analysis of Multi-Fractured Horizontal Wells in Unconventional Gas Reservoirs
    Journal of Natural Gas Science and Engineering, 2019
    Co-Authors: Miao Zhang, Luis F. Ayala
    Abstract:

    Abstract Application of superposition principle to non-linear gas governing Equations has been an elusive goal in early-transient production data analysis and has been so far limited to the use of empirical and approximate methods best applicable to boundary-dominated flow conditions. This paper presents a novel and rigorous semi-analytical model that is applicable for the analysis of production data from multi-fractured horizontal gas wells (MFHWs) producing under early-transient variable rate/pressure production conditions. Nonlinear, pressure-dependent hydraulic Diffusivity retained in pseudo-pressure-based gas Diffusivity Equation is straightforwardly and rigorously captured without approximation. The resulting formulation of superposition applied in nonlinear gas system is written in terms of the classical solution for the governing linear partial differential Equation (PDE) plus an analytical adjustment factor that quantifies the nonlinearity of the system. Numerical examples and field cases are presented to test the validity and showcase the capabilities of proposed approach. Comparisons against available empirical and approximate models are also provided for these cases.

  • application of superposition principle to variable rate pressure production analysis of multi fractured horizontal wells in unconventional gas reservoirs
    Journal of Natural Gas Science and Engineering, 2019
    Co-Authors: Miao Zhang, Luis F. Ayala
    Abstract:

    Abstract Application of superposition principle to non-linear gas governing Equations has been an elusive goal in early-transient production data analysis and has been so far limited to the use of empirical and approximate methods best applicable to boundary-dominated flow conditions. This paper presents a novel and rigorous semi-analytical model that is applicable for the analysis of production data from multi-fractured horizontal gas wells (MFHWs) producing under early-transient variable rate/pressure production conditions. Nonlinear, pressure-dependent hydraulic Diffusivity retained in pseudo-pressure-based gas Diffusivity Equation is straightforwardly and rigorously captured without approximation. The resulting formulation of superposition applied in nonlinear gas system is written in terms of the classical solution for the governing linear partial differential Equation (PDE) plus an analytical adjustment factor that quantifies the nonlinearity of the system. Numerical examples and field cases are presented to test the validity and showcase the capabilities of proposed approach. Comparisons against available empirical and approximate models are also provided for these cases.

  • variable rate and pressure integral solutions to the nonlinear gas Diffusivity Equation in unconventional systems
    Fuel, 2019
    Co-Authors: Miao Zhang, Luis F. Ayala
    Abstract:

    Abstract Unconventional gas resources, including tight gas and shale gas, are becoming major sources of natural gas production in U.S. Commercial production from tight or ultra-tight formations requires horizontal wells and massive hydraulic fracturing treatment. These multi-fractured horizontal wells (MFHWs) can exhibit long-term (typically years) early-transient behavior prior to pressure transient reaching the reservoir boundary. Analytical models that have been traditionally developed for transient flow in conventional gas reservoirs face significant challenges when applied to unconventional tight and shale gas, particularly when variable-rate and variable-pressure data needs to be analyzed. This paper presents a rigorous and direct semi-analytical integral solution to the governing nonlinear gas Diffusivity Equations that are directly applicable to realistic unconventional production scenarios of MFHWs. The validity of proposed solution is verified by matching against numerical simulation results using synthetic case studies for both constant and varying rate production conditions. Its applicability to real-life production scenarios is showcased by a field case study using production data from a MFHW in Marcellus Shale.

C.s. Kabir - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of heat-flow rate: A precursor to the transient-temperature analysis
    Geothermics, 2020
    Co-Authors: A.q. Al Saedi, C.s. Kabir
    Abstract:

    Abstract Fluids in a reservoir remain in equilibrium condition before the onset of any wellbore operation. This equilibrium pertains to both the fluid pressure and temperature. Inducing any wellbore activity, such as mud circulation in drilling and fluid production precipitate changes in both the pressure and temperature responses. For an infinite-acting system, we can solve the governing temperature Diffusivity Equation by adopting the line-source solution. The difference between the pressure and temperature Diffusivity Equation allows us to investigate an independent line-source solution for the temperature-Diffusivity Equation. After obtaining the temperature line-source solution, we determined the temperature behavior for different wellbore temperature measurements during the shut-in period, such as those reflecting buildup and falloff responses. This study presents a mathematical approach to study the temperature falloff measurements and another method for the buildup temperature dataset. In particular, we used the estimated heat-flow rate to convolve with temperature for improving the quality of initial-formation temperature estimation. Finally, the heat flow corresponding to each timestep and the application of superposition principle was also investigated. The temperature line-source solution represented the backbone for all suggested approaches.

  • exploring alteration of near wellbore geothermal gradient during fluid circulation and production
    Journal of Petroleum Science and Engineering, 2019
    Co-Authors: A Al Q Saedi, C.s. Kabir, Ralph E Flori
    Abstract:

    Abstract The constant undisturbed formation temperature profile controlling heat transfer into the wellbore appears counterintuitive in light of transient cooling of the formation that occurs upon fluid circulation in drilling and also heating during fluid production. This study presents a mathematical model that shows that the heat transfer occurs from the wellbore/formation interface, not from some distance away from the wellbore wherein the initial formation temperature profile remains undisturbed. This new model allows investigation of heat transfer behavior from the formation into the wellbore during drilling or fluid circulation, and from the wellbore into the reservoir in the production mode. Application of the line-source solution for the temperature Diffusivity Equation for a steady-state system provides the necessary ingredients for computing the temperature behaviors at different times and radii. This line-source solution can be used throughout the wellbore to determine the undisturbed formation temperature, which may be used to obtain the geothermal gradient dependent on the radius and fluid circulation time. Therefore, the initial geothermal gradient works as a time-dependent variable, and the resultant second-order polynomial relationships can describe the undisturbed formation temperature. This study provides the required tools to assess the wellbore heat-transfer behavior and their effect on the wellbore temperature profiles. Also, the new mathematical model illuminates the impact of heat transfer by comparing its performance with the original formulations. Besides, this paper presents a complete derivation of the line-source solution of the temperature Diffusivity Equation to justify the proposed approach.

  • Aspects of Wellbore Heat Transfer During Two-Phase Flow (includes associated papers 30226 and 30970 )
    Spe Production & Facilities, 1994
    Co-Authors: A.r. Hasan, C.s. Kabir
    Abstract:

    Wellbore fluid temperature is governed by the rate of heat loss from the wellbore to the surrounding formation, which in turn is a function of depth and production/injection time. The authors present an approach to estimate wellbore fluid temperature during steady-state two-phase flow. The method incorporates a new solution of the thermal Diffusivity Equation and the effect of both conductive and convective heat transport for the wellbore/formation system. For the multiphase flow in the wellbore, the Hasan-Kabir model has been adapted, although other mechanistic models may be used. A field example is used to illustrate the fluid temperature calculation procedure and shows the importance of accounting for convection in the tubing/casing annulus. A sensitivity study shows that significant differences exist between the predicted wellhead temperature and the formation surface temperature and that the fluid temperature gradient is nonlinear. This study further shows that increased free gas lowers the wellhead temperature as a result of the Joule-Thompson effect. In such cases, the expression for fluid temperature developed earlier for single-phase flow should not be applied when multiphase flow is encountered. An appropriate expression is presented in this work for wellbores producing multiphase fluids.

Zhangxin Chen - One of the best experts on this subject based on the ideXlab platform.

  • semi analytical solution for pressure transient analysis of a hydraulically fractured vertical well in a bounded dual porosity reservoir
    Journal of Hydrology, 2018
    Co-Authors: Morteza Dejam, Hassan Hassanzadeh, Zhangxin Chen
    Abstract:

    Abstract We study the role of a hydraulic fracture on the pressure transient behavior of a vertical well producing from a bounded (or finite) dual-porosity formation. A combination of Laplace transform (LT) and the finite Fourier cosine transform (FFCT) are used to solve the Diffusivity Equation. The presented analysis allows identification of five flow regimes, including: 1) early linear flow, 2) volumetric depletion of natural fractures, 3) natural-fracture radial flow, 4) transition from natural-fracture radial flow to total (natural fractures and matrix) radial flow, and 5) pseudo-steady state flow. The results reveal that the interporosity flow coefficient, storativity ratio, natural-fracture permeability anisotropy, and reservoir size play significant roles on the identified flow regimes compared to the hydraulically fractured well location and reservoir shape. The developed solution can be useful for well test analysis by generating a new set of type curves or can be applicable to a forward model for estimating parameters of reservoir. This study presents a new semi-analytical solution which finds application in well testing of hydraulically fractured wells in dual-porosity formations.

  • Semi-Analytical Solutions for a Partially Penetrated Well with Wellbore Storage and Skin Effects in a Double-Porosity System with a Gas Cap
    Transport in Porous Media, 2013
    Co-Authors: Morteza Dejam, Zhangxin Chen
    Abstract:

    We have studied the effect of a constant top pressure on the pressure transient analysis of a partially penetrated well in an infinite-acting fractured reservoir with wellbore storage and skin factor effects. Semi-analytical solutions of a two-dimensional Diffusivity Equation have been obtained by using successive applications of the Laplace and modified finite Fourier sine transforms. Both pseudo-steady-state and transient exchanges between the matrix and the fractures have been considered. Solutions are presented that can be used to generate type curves for pressure transient analysis or can be used as a forward model in parameter estimation. The presented analysis has applications in well testing of fractured aquifers and naturally fractured oil reservoirs with a gas cap.

Morteza Dejam - One of the best experts on this subject based on the ideXlab platform.

  • semi analytical solution for pressure transient analysis of a hydraulically fractured vertical well in a bounded dual porosity reservoir
    Journal of Hydrology, 2018
    Co-Authors: Morteza Dejam, Hassan Hassanzadeh, Zhangxin Chen
    Abstract:

    Abstract We study the role of a hydraulic fracture on the pressure transient behavior of a vertical well producing from a bounded (or finite) dual-porosity formation. A combination of Laplace transform (LT) and the finite Fourier cosine transform (FFCT) are used to solve the Diffusivity Equation. The presented analysis allows identification of five flow regimes, including: 1) early linear flow, 2) volumetric depletion of natural fractures, 3) natural-fracture radial flow, 4) transition from natural-fracture radial flow to total (natural fractures and matrix) radial flow, and 5) pseudo-steady state flow. The results reveal that the interporosity flow coefficient, storativity ratio, natural-fracture permeability anisotropy, and reservoir size play significant roles on the identified flow regimes compared to the hydraulically fractured well location and reservoir shape. The developed solution can be useful for well test analysis by generating a new set of type curves or can be applicable to a forward model for estimating parameters of reservoir. This study presents a new semi-analytical solution which finds application in well testing of hydraulically fractured wells in dual-porosity formations.

  • Semi-Analytical Solutions for a Partially Penetrated Well with Wellbore Storage and Skin Effects in a Double-Porosity System with a Gas Cap
    Transport in Porous Media, 2013
    Co-Authors: Morteza Dejam, Zhangxin Chen
    Abstract:

    We have studied the effect of a constant top pressure on the pressure transient analysis of a partially penetrated well in an infinite-acting fractured reservoir with wellbore storage and skin factor effects. Semi-analytical solutions of a two-dimensional Diffusivity Equation have been obtained by using successive applications of the Laplace and modified finite Fourier sine transforms. Both pseudo-steady-state and transient exchanges between the matrix and the fractures have been considered. Solutions are presented that can be used to generate type curves for pressure transient analysis or can be used as a forward model in parameter estimation. The presented analysis has applications in well testing of fractured aquifers and naturally fractured oil reservoirs with a gas cap.