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K E Gray - One of the best experts on this subject based on the ideXlab platform.
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thixotropy effects on Drilling Hydraulics
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Shiraz Gulraiz, K E GrayAbstract:Abstract Thixotropy is the reversible breakdown of fluid microstructure when sheared. The microstructure achieves a new steady-state once shearing stops. Drilling fluids are thixotropic due to their rheological makeup which means that fluid microstructure has a time-dependent response to changes in applied shear rate. In contrast to the literature focusing on the time-independent nature of Drilling fluid, few studies have focused on the time-dependent response and even fewer have considered cuttings transport while doing so. The purpose of this study is to investigate the fundamental relationship between thixotropy and Drilling Hydraulics. An algorithm is developed to model thixotropy using flow history. The results show that the addition of drill cuttings does not directly affect the thixotropic behavior, rather the steady-state response is impacted which consequently changes the thixotropic response. Since the fluid microstructure takes time to respond to shear rate variations, viscosity lags behind shear rate variations causing annular pressure loss to fluctuate. The magnitude of pressure fluctuations is inversely proportional to characteristic time and directly proportional to stretching exponent. At smaller characteristic time coupled with smaller stretching exponent, high yield stress deteriorates cuttings transport. For larger values of characteristic time and stretching exponent, a clear trend is not observed, and further investigation is recommended. Nevertheless, when the thixotropic behavior of Drilling fluid is considered, the results show that high flow rates and yield stresses do not guarantee efficient hole cleaning. Out of the two industrial fluid samples discussed, WBM yields higher pressure fluctuations and better cuttings transport compared to OBM. Since the proposed algorithm does not differentiate between the types of Drilling fluids, this is due to WBM’s smaller characteristic time and larger stretching exponent. It is suggested that a fluid exhibiting a slower response to shear rate changes causes higher pressure fluctuations and better cuttings transport.
Oscar C. Valdiviezo-mijangos - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Wellbore Drilling Hydraulics Applying a Transient Godunov Scheme Considering Variations of Injected Flow Rates
International Journal of Oil Gas and Coal Engineering, 2017Co-Authors: Rubén Nicolás-lópez, Angel J. Sánchez-barra, Oscar C. Valdiviezo-mijangosAbstract:A new application of the Godunov scheme to describe dynamic oil-well behavior is presented. The numerical model is able to capture discontinuities associated with surface flow-rate variations. The finite volume method and Riemann problems are utilized for building the unsteady discrete solution. Initial and boundary conditions are related to cases of static, steady and transient well condition. Well data used in simulation are taken from true operational conditions and well mechanical configuration. The results of Godunov’s modeling describe the behavior of transient pressure and transient flow rate inside drill pipe and annulus. These profiles are commonly caused by turning on, adjusting mud flow rate and turning off the rig pumps. The evaluated rig indicators are: back pressure, pumping pressure, bottomhole pressure and injected flow rate. Calculated transient profiles are physically consistent and in good agreement with published well data. Therefore, engineering contribution is the application of first-order Godunov method to evaluate the transient Hydraulics whereas variations of mud flow rate; also, the analysis and interpretation of the dynamic pressure behavior travelling inside the well. The Godunov scheme has robust engineering applications for modeling the transient Drilling Hydraulics, e.g., managed pressure Drilling, Hydraulics of pipe connections, and foam cementing, as well.
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Dynamic modeling of managed pressure Drilling applying transient Godunov scheme
Journal of Petroleum Exploration and Production Technology, 2016Co-Authors: Angel J. Sánchez-barra, Rubén Nicolás-lópez, Oscar C. Valdiviezo-mijangos, Abel Camacho-galvánAbstract:Transient Hydraulics always characterizes the circulating flow during managed pressure Drilling. Therefore, the application of the Godunov scheme to oil-well Drilling Hydraulics is presented. The numerical model developed describes the treatment process of the initial and boundary conditions from the well geometry and true operational conditions. The well-known finite-volume method and Riemann problem are utilized for building the set of discrete equations. The account of Godunov’s simulation describes the profiles of transient pressure and transient flow rate along the well. For attending the oil-field engineering concerns, the Drilling parameters discussed are as follows: choke pressure, pumping pressure, bottom-hole pressure, and circulating flow rate. After the comparison between computed and well data, the results show a small difference of less than 7 and 1 % for pumping and bottom-hole pressures, respectively. The main engineering contribution of this work is the solution and application of the first-order Godunov scheme to analyze the transient Hydraulics during actual oil-well Drilling and also the analysis and interpretation of the pressure wave behavior traveling along the well. The Godunov scheme has high-potential engineering applications for modeling the transient Drilling Hydraulics, i.e., controlled flow, underbalanced Drilling, and foam cementing, as well.
Angel J. Sánchez-barra - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Wellbore Drilling Hydraulics Applying a Transient Godunov Scheme Considering Variations of Injected Flow Rates
International Journal of Oil Gas and Coal Engineering, 2017Co-Authors: Rubén Nicolás-lópez, Angel J. Sánchez-barra, Oscar C. Valdiviezo-mijangosAbstract:A new application of the Godunov scheme to describe dynamic oil-well behavior is presented. The numerical model is able to capture discontinuities associated with surface flow-rate variations. The finite volume method and Riemann problems are utilized for building the unsteady discrete solution. Initial and boundary conditions are related to cases of static, steady and transient well condition. Well data used in simulation are taken from true operational conditions and well mechanical configuration. The results of Godunov’s modeling describe the behavior of transient pressure and transient flow rate inside drill pipe and annulus. These profiles are commonly caused by turning on, adjusting mud flow rate and turning off the rig pumps. The evaluated rig indicators are: back pressure, pumping pressure, bottomhole pressure and injected flow rate. Calculated transient profiles are physically consistent and in good agreement with published well data. Therefore, engineering contribution is the application of first-order Godunov method to evaluate the transient Hydraulics whereas variations of mud flow rate; also, the analysis and interpretation of the dynamic pressure behavior travelling inside the well. The Godunov scheme has robust engineering applications for modeling the transient Drilling Hydraulics, e.g., managed pressure Drilling, Hydraulics of pipe connections, and foam cementing, as well.
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Dynamic modeling of managed pressure Drilling applying transient Godunov scheme
Journal of Petroleum Exploration and Production Technology, 2016Co-Authors: Angel J. Sánchez-barra, Rubén Nicolás-lópez, Oscar C. Valdiviezo-mijangos, Abel Camacho-galvánAbstract:Transient Hydraulics always characterizes the circulating flow during managed pressure Drilling. Therefore, the application of the Godunov scheme to oil-well Drilling Hydraulics is presented. The numerical model developed describes the treatment process of the initial and boundary conditions from the well geometry and true operational conditions. The well-known finite-volume method and Riemann problem are utilized for building the set of discrete equations. The account of Godunov’s simulation describes the profiles of transient pressure and transient flow rate along the well. For attending the oil-field engineering concerns, the Drilling parameters discussed are as follows: choke pressure, pumping pressure, bottom-hole pressure, and circulating flow rate. After the comparison between computed and well data, the results show a small difference of less than 7 and 1 % for pumping and bottom-hole pressures, respectively. The main engineering contribution of this work is the solution and application of the first-order Godunov scheme to analyze the transient Hydraulics during actual oil-well Drilling and also the analysis and interpretation of the pressure wave behavior traveling along the well. The Godunov scheme has high-potential engineering applications for modeling the transient Drilling Hydraulics, i.e., controlled flow, underbalanced Drilling, and foam cementing, as well.
Rubén Nicolás-lópez - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Wellbore Drilling Hydraulics Applying a Transient Godunov Scheme Considering Variations of Injected Flow Rates
International Journal of Oil Gas and Coal Engineering, 2017Co-Authors: Rubén Nicolás-lópez, Angel J. Sánchez-barra, Oscar C. Valdiviezo-mijangosAbstract:A new application of the Godunov scheme to describe dynamic oil-well behavior is presented. The numerical model is able to capture discontinuities associated with surface flow-rate variations. The finite volume method and Riemann problems are utilized for building the unsteady discrete solution. Initial and boundary conditions are related to cases of static, steady and transient well condition. Well data used in simulation are taken from true operational conditions and well mechanical configuration. The results of Godunov’s modeling describe the behavior of transient pressure and transient flow rate inside drill pipe and annulus. These profiles are commonly caused by turning on, adjusting mud flow rate and turning off the rig pumps. The evaluated rig indicators are: back pressure, pumping pressure, bottomhole pressure and injected flow rate. Calculated transient profiles are physically consistent and in good agreement with published well data. Therefore, engineering contribution is the application of first-order Godunov method to evaluate the transient Hydraulics whereas variations of mud flow rate; also, the analysis and interpretation of the dynamic pressure behavior travelling inside the well. The Godunov scheme has robust engineering applications for modeling the transient Drilling Hydraulics, e.g., managed pressure Drilling, Hydraulics of pipe connections, and foam cementing, as well.
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Dynamic modeling of managed pressure Drilling applying transient Godunov scheme
Journal of Petroleum Exploration and Production Technology, 2016Co-Authors: Angel J. Sánchez-barra, Rubén Nicolás-lópez, Oscar C. Valdiviezo-mijangos, Abel Camacho-galvánAbstract:Transient Hydraulics always characterizes the circulating flow during managed pressure Drilling. Therefore, the application of the Godunov scheme to oil-well Drilling Hydraulics is presented. The numerical model developed describes the treatment process of the initial and boundary conditions from the well geometry and true operational conditions. The well-known finite-volume method and Riemann problem are utilized for building the set of discrete equations. The account of Godunov’s simulation describes the profiles of transient pressure and transient flow rate along the well. For attending the oil-field engineering concerns, the Drilling parameters discussed are as follows: choke pressure, pumping pressure, bottom-hole pressure, and circulating flow rate. After the comparison between computed and well data, the results show a small difference of less than 7 and 1 % for pumping and bottom-hole pressures, respectively. The main engineering contribution of this work is the solution and application of the first-order Godunov scheme to analyze the transient Hydraulics during actual oil-well Drilling and also the analysis and interpretation of the pressure wave behavior traveling along the well. The Godunov scheme has high-potential engineering applications for modeling the transient Drilling Hydraulics, i.e., controlled flow, underbalanced Drilling, and foam cementing, as well.
Shiraz Gulraiz - One of the best experts on this subject based on the ideXlab platform.
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thixotropy effects on Drilling Hydraulics
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Shiraz Gulraiz, K E GrayAbstract:Abstract Thixotropy is the reversible breakdown of fluid microstructure when sheared. The microstructure achieves a new steady-state once shearing stops. Drilling fluids are thixotropic due to their rheological makeup which means that fluid microstructure has a time-dependent response to changes in applied shear rate. In contrast to the literature focusing on the time-independent nature of Drilling fluid, few studies have focused on the time-dependent response and even fewer have considered cuttings transport while doing so. The purpose of this study is to investigate the fundamental relationship between thixotropy and Drilling Hydraulics. An algorithm is developed to model thixotropy using flow history. The results show that the addition of drill cuttings does not directly affect the thixotropic behavior, rather the steady-state response is impacted which consequently changes the thixotropic response. Since the fluid microstructure takes time to respond to shear rate variations, viscosity lags behind shear rate variations causing annular pressure loss to fluctuate. The magnitude of pressure fluctuations is inversely proportional to characteristic time and directly proportional to stretching exponent. At smaller characteristic time coupled with smaller stretching exponent, high yield stress deteriorates cuttings transport. For larger values of characteristic time and stretching exponent, a clear trend is not observed, and further investigation is recommended. Nevertheless, when the thixotropic behavior of Drilling fluid is considered, the results show that high flow rates and yield stresses do not guarantee efficient hole cleaning. Out of the two industrial fluid samples discussed, WBM yields higher pressure fluctuations and better cuttings transport compared to OBM. Since the proposed algorithm does not differentiate between the types of Drilling fluids, this is due to WBM’s smaller characteristic time and larger stretching exponent. It is suggested that a fluid exhibiting a slower response to shear rate changes causes higher pressure fluctuations and better cuttings transport.
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Investigating the effects of plug viscosity on annular pressure drop and cuttings transport in a concentric annulus
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Shiraz Gulraiz, Kenneth E. GrayAbstract:Abstract The API recommended approach to model the rheology of a Drilling fluid is to use the Herschel Bulkley equation. This equation breaks down as shear rate approaches zero and predicts infinite viscosity at zero shear rate limit. In an annulus, shear rate can drop to values approaching zero and the use of Herschel Bulkley equation in flow models can lead to inaccurate prediction of Drilling Hydraulics. This paper investigates the effects of zero shear rate viscosity, called plug viscosity, on annular pressure drop and cuttings transport predictions in a concentric annulus. Flow is modeled using the mixture model approach and is simulated using computational fluid dynamics (CFD) methodology. The rheology of the Drilling fluid is characterized using a modified bi-viscosity function. The first half of this paper examines the effect of common Drilling parameters on the existence of plug zones, regions with zero shear rate viscosity, whereas the second half of this paper investigates the effects of plug viscosity on annular pressure profile and cuttings transport. The results show that plug viscosity has a significant impact on annular pressure profile and cuttings transport predictions. The same set of Herschel Bulkley parameters can produce different values of annular pressure drop and volumetric cuttings concentration if plug viscosity is ignored. Therefore, to accurately predict annular pressure profile and cuttings transport, it is imperative that plug viscosity is incorporated in the rheological functions.
