The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numeric... more The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numerically through channels of varying thickness for fluids undergoing creeping flow. Exact analytical solutions of mass conservation equations of tracer particles including consideration for pressure forces are obtained. Results of the analysis indicates that Stokes velocity is an indispensable parameter and is dependent on parameters such as channel thickness (height), viscosity of the fluid, pressure gradient driven the fluid and Reynolds number corresponding to the channel thickness. The accuracy of the solution obtained is verified by comparing its velocity profiles with those obtained from finite-element-based numerical simulation studies.
Sand production due to result of unconsolidated grains in wellbore formations, as lead to many ad... more Sand production due to result of unconsolidated grains in wellbore formations, as lead to many adverse effect, such as plugging, accumulation in surface equipment, increase in skin and tubing roughness. Sensitivity analysis using PROSPER software was run on different well parameters, (tubing roughness, skin) and under free gas effect for an open hole completion to predict effect of sand production in life of the well. The tubing and skin analysis shows a decline in well flow potential across the years, due to sand production. The future performance indicate sand control remedy must be deploy to maintain and revive the well to it optimum flow potential. Analysis on free gas effect was used to determine the highest free gas value under the reservoir condition for the well optimum production. (3.5 - 4.023) MMscf/day gave the optimal flow potential for the well. This analysis shows the amount and condition of free gas in the well before the effect of sand production
The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numeric... more The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numerically through channels of varying thickness for fluids undergoing creeping flow. Exact analytical solutions of mass conservation equations of tracer particles including consideration for pressure forces are obtained. Results of the analysis indicates that Stokes velocity is an indispensable parameter and is dependent on parameters such as channel thickness (height), viscosity of the fluid, pressure gradient driven the fluid and Reynolds number corresponding to the channel thickness. The accuracy of the solution obtained is verified by comparing its velocity profiles with those obtained from finite-element-based numerical simulation studies.
Sulphur deposition, most times, has been attributed to reservoir sour gases. Sulphur deposition a... more Sulphur deposition, most times, has been attributed to reservoir sour gases. Sulphur deposition as a solid has often resulted in plugging reservoir pore spaces available for gas flow and reduces the reservoir productivity in sour gas reservoirs. Reduction in reservoir pressure causes elemental sulphur to precipitate out of the reservoir fluid and is deposited in the formation. In this work, a mathematical model depicting sulphur solubility and saturation at certain reservoir pressures and temperatures was developed using Chrastil correlation. The gas density was determined from the general law at reservoir conditions and the gas compressibility factor was determined at a certain reservoir conditions using Abu-Elkassem correlation by iterations using FORTRAN. The gas properties were considered to change as the reservoir pressure declines. As compared to the previous models, the viscosity of the natural gas was estimated using the accepted correlation method. Along with the fact that ...
A research work was carried out to investigate the effect of hydrochloric acid on manganese tetra... more A research work was carried out to investigate the effect of hydrochloric acid on manganese tetraoxide water-based drilling fluid. Filter cake was produced using the HPHT (High pressure, High temperature) filter press machine and the cake was dissolved in various HCl concentrations ranging between 1-10 wt% at various temperatures. Results obtained indicates that only dissolve of filter cake at 10 wt% HCl was possible at ambient temperatures.At elevated temperatures, above the acid concentration of 3 wt%, there was formation of chlorine gas. It was also noticed that dissolution times decreased with increasing temperature. Therefore, for optimum utilization and environmental safety, HCl concentration should not exceed 3 wt% especially at high temperature. Keywords—Hydrochloric acid, Manganese tetraoxide, Water based drilling fluid, HPHT, Ambient temperatures, Filter cake, Elevated temperatures, Concentrations.
This paper reports an analytical study conducted to investigate the behaviour of tracers undergoi... more This paper reports an analytical study conducted to investigate the behaviour of tracers undergoing creeping flow between two parallel plates in porous media. A new coupled model for the characterisation of fluid flow and transport of tracers at pore scale is formulated. Precisely, a weak-form solution of radial transport of tracers under convection–diffusion-dominated flow is established using hypergeometric functions. The velocity field associated with the radial transport is informed by the solution of the Stokes equations. Channel thickness as a function of velocities, maximum Reynolds number of each thickness as a function of maximum velocities and concentration profile for different drift and dispersion coefficients are computed and analysed. Analysis of the simulation results reveals that the dispersion coefficient appears to be a significant factor controlling the concentration distribution of the tracer at pore scale. Further analysis shows that the drift coefficient appear...
SPE Nigeria Annual International Conference and Exhibition, 2018
Homotopy analytical method (HAM) is a computational method that provides solution to highly non-l... more Homotopy analytical method (HAM) is a computational method that provides solution to highly non-linear partial differential equations (PDE's) in much similar way as other perturbation and asymptotic techniques. This research work illustrates the benefit of using (HAM) to obtain a type curve over conventional log approximation of dimensionless variables. From such type curves, average reservoir properties, porosity and permeability were obtained from dimensionless equations. This type curve was obtained by matching plots from HAM solution and well test data. The HAM is independent of small/large parameter and can be used to obtain analytical solutions to highly nonlinear partial differential equations unlike other analytical and asymptotic techniques applies to weakly nonlinear problems. The HAM solution gives values of reservoir pressure distribution as a continuous function of time and converges easily for large reservoirs (rD =380) typically. One advantage of HAM is that it provides a means to ensure convergence of series solution by introduction of convergent control parameter. Plots of reservoir pressure distribution as a function of time curves were also obtained and extrapolated for easy matching and were matched with the type curve. Dimensionless pressure and time were used to compute average porosity and permeability which were found to be 1.51md permeability and 1.81% porosity. Computer program was developed for computations using MATLAB and further analysis of data using EXCEL. From the match points obtained, reservoir properties were estimated.
This investigation demonstrates the use of acentric factor as the third parameter in a correspond... more This investigation demonstrates the use of acentric factor as the third parameter in a corresponding states correlation for compressibility factors and a discussion of their application to three different types of gas reservoir.A correlation is presented which provides compressibility factors based on Hall – Yarborough equation of states for use in both two – phase and single-phase hydrocarbon systems. The modified Hall - Yarborough equation employs the acentric factor as an additional parameter to improve its accuracy. This modified equation is as simple as the original form, yet achieves substantially better prediction accuracy, especially at higher pressure.The correlation is based on hydrocarbon compressibility determinations from twenty-two hydrocarbon samples taken from three different types of reservoir systems. Out of the data used 67 percent were from dew point or retrograde gas condensate and bubble point or dissolved gas reservoir, 33 percent were from single phase gas re...
ABSTRACT Filtrate losses and filter cake properties of drilling fluids are of concern in the oil ... more ABSTRACT Filtrate losses and filter cake properties of drilling fluids are of concern in the oil industry because they alter near wellbore permeability and can reduce well productivity. Therefore, it is desirable to accurately characterize filtration process during oil well drilling. A mathematical model for analyzing mud filtration in deviated wells was developed in this study. The model determined solid pressure distribution within cake, cake thickness, cumulative volume of filtrate, and extent of invasion under different conditions. Results show assumptions of isotropy in previous studies greatly overestimate the magnitude of the damage. It was also confirmed that mud filtration tend to be higher in deviated than in vertical wells. The model was validated with experimental data.
Research has shown that faults, especially sealing faults, have become a barrier to flow. Flow di... more Research has shown that faults, especially sealing faults, have become a barrier to flow. Flow diagnostics, on the other hand, are straightforward and controlled numerical flow experiments that are performed to examine a reservoir model, build links and offer rudimentary volume estimates as well as to quickly produce a qualitative representation of the reservoir's flow patterns. To evaluate, assess, and validate reservoir models and production scenarios, the 'diagnostics' module in the Matlab Reservoir Simulation Toolbox (MRST) provides a computationally less expensive alternative to running fully featured multiphase simulations. This is done to determine qualitatively regions for well placement to maximize hydrocarbon recovery. Monitoring flow fields, timelines, and tracers-neutral particles in the fluid that flow with the fluid-are all part of flow diagnostics. These techniques are used to determine volumetric communication between a pair of injector-producer wells, as well as flow patterns between injection-production wells and the arrival time between them. To create the grid, the simulation schedule, the wells, upscaling, arrival time computation, and flow diagnostics (drainage and sweep regions) were all done using the Matlab reservoir simulation toolbox (MRST) package by "Makemodel 3" on the data obtained from "SPE 10 th comparative solution project" on the MRST package. This was done for a homogeneous anisotropic faulted porous medium. The simulation runs for about 473,739 milliseconds on a fine grid having 20040 active cells while in the coarse model with faster computational time of about 200 seconds, 112 milliseconds. At the early stages of the reservoir bottom-hole pressure for injector I1(about 7000psia) and three producers P1, P2 and P3 remains constant over time (about 3600psia) thanks to pressure support by I1. The extent of residence time after 10 years for the fine, coarse and more coarser model is that fluid element find it easier to transverse through the fault line from I1 to P1, P2 then P3 which takes lesser time than crossing across two intersecting faults, It can also be seen that the sweep efficiency of the fine grid is more effective than the coarse grid. Finally, it has been seen clearly that the fine grid model gives more accurate details but slower computational time while the coarse model which is less accurate but with faster computational time.
Sand production due to result of unconsolidated grains in wellbore formations, as lead to many ad... more Sand production due to result of unconsolidated grains in wellbore formations, as lead to many adverse effect, such as plugging, accumulation in surface equipment, increase in skin and tubing roughness. Sensitivity analysis using PROSPER software was run on different well parameters, (tubing roughness, skin) and under free gas effect for an open hole completion to predict effect of sand production in life of the well. The tubing and skin analysis shows a decline in well flow potential across the years, due to sand production. The future performance indicate sand control remedy must be deploy to maintain and revive the well to it optimum flow potential. Analysis on free gas effect was used to determine the highest free gas value under the reservoir condition for the well optimum production. (3.5-4.023) MMscf/day gave the optimal flow potential for the well. This analysis shows the amount and condition of free gas in the well before the effect of sand production. INTRODUCTION Sand prediction model have the capability to indicate whether initial sand production may take place somewhere during the lifetime of an oil gas field. Prediction of maximum sand-free production rate provides information for sand-control decisions and allows maximization of rate in those wells that are completed without sand control. In this paper, filed data will be used for modelling and making this predictions. A significant proportion of the world gas reserves is contained in weakly consolidated sandstone reservoirs and hence is prone to sand production. Material degradation is a key process leading to sanding. Drilling operations, cyclic effects of shut-in and start-up, operational conditions, reservoir pressure depletion, and strength-weakening effect of water may gradually lead to sandstone degradation around the perforations and boreholes. High pressure gradient due to fluid flow also facilitates the detachment of sand particles. In addition, fluid flow is responsible for the transport and production of cohesionless sand particles or detached sand clumps to the wellbore. Sand production is the cause of many problems in the oil industry and it affects the completion adversely. These problems include, but are not limited to, plugging the perforations or production liner, wellbore instability, failure of sand control completions Sand-production problems can be experienced in various ways. In conventional oil wells, transient sand production, where the sand production rate declines rapidly with time, is frequently experienced during the clean-up period after processes such as perforating or acidizing, after rapid bean-up of production, or after water breakthrough. It is assumed that sand production in these cases is merely the removal of weakened or sheared and dilated sand. However, there are different " types " of sand-production behavior. Conventional-oil sand production has been classified on the basis of distinct reservoir evolution stages: The early transient sand-production period, when some of the perforation-induced damage has been removed and the cavities may have a zone of reduced permeability around them, leading to a steep exit gradient. A stable production period with enlarged cavities, when the damaged zone and the permeability impairment have been removed. A general increase in sand influx after a water-cut increase, a process that is considered to be related to capillary forces and is a type of flow-rate-induced sand production.
The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numeric... more The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numerically through channels of varying thickness for fluids undergoing creeping flow. Exact analytical solutions of mass conservation equations of tracer particles including consideration for pressure forces are obtained. Results of the analysis indicates that Stokes velocity is an indispensable parameter and is dependent on parameters such as channel thickness (height), viscosity of the fluid, pressure gradient driven the fluid and Reynolds number corresponding to the channel thickness. The accuracy of the solution obtained is verified by comparing its velocity profiles with those obtained from finite-element-based numerical simulation studies.
Sand production due to result of unconsolidated grains in wellbore formations, as lead to many ad... more Sand production due to result of unconsolidated grains in wellbore formations, as lead to many adverse effect, such as plugging, accumulation in surface equipment, increase in skin and tubing roughness. Sensitivity analysis using PROSPER software was run on different well parameters, (tubing roughness, skin) and under free gas effect for an open hole completion to predict effect of sand production in life of the well. The tubing and skin analysis shows a decline in well flow potential across the years, due to sand production. The future performance indicate sand control remedy must be deploy to maintain and revive the well to it optimum flow potential. Analysis on free gas effect was used to determine the highest free gas value under the reservoir condition for the well optimum production. (3.5 - 4.023) MMscf/day gave the optimal flow potential for the well. This analysis shows the amount and condition of free gas in the well before the effect of sand production
The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numeric... more The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numerically through channels of varying thickness for fluids undergoing creeping flow. Exact analytical solutions of mass conservation equations of tracer particles including consideration for pressure forces are obtained. Results of the analysis indicates that Stokes velocity is an indispensable parameter and is dependent on parameters such as channel thickness (height), viscosity of the fluid, pressure gradient driven the fluid and Reynolds number corresponding to the channel thickness. The accuracy of the solution obtained is verified by comparing its velocity profiles with those obtained from finite-element-based numerical simulation studies.
Sulphur deposition, most times, has been attributed to reservoir sour gases. Sulphur deposition a... more Sulphur deposition, most times, has been attributed to reservoir sour gases. Sulphur deposition as a solid has often resulted in plugging reservoir pore spaces available for gas flow and reduces the reservoir productivity in sour gas reservoirs. Reduction in reservoir pressure causes elemental sulphur to precipitate out of the reservoir fluid and is deposited in the formation. In this work, a mathematical model depicting sulphur solubility and saturation at certain reservoir pressures and temperatures was developed using Chrastil correlation. The gas density was determined from the general law at reservoir conditions and the gas compressibility factor was determined at a certain reservoir conditions using Abu-Elkassem correlation by iterations using FORTRAN. The gas properties were considered to change as the reservoir pressure declines. As compared to the previous models, the viscosity of the natural gas was estimated using the accepted correlation method. Along with the fact that ...
A research work was carried out to investigate the effect of hydrochloric acid on manganese tetra... more A research work was carried out to investigate the effect of hydrochloric acid on manganese tetraoxide water-based drilling fluid. Filter cake was produced using the HPHT (High pressure, High temperature) filter press machine and the cake was dissolved in various HCl concentrations ranging between 1-10 wt% at various temperatures. Results obtained indicates that only dissolve of filter cake at 10 wt% HCl was possible at ambient temperatures.At elevated temperatures, above the acid concentration of 3 wt%, there was formation of chlorine gas. It was also noticed that dissolution times decreased with increasing temperature. Therefore, for optimum utilization and environmental safety, HCl concentration should not exceed 3 wt% especially at high temperature. Keywords—Hydrochloric acid, Manganese tetraoxide, Water based drilling fluid, HPHT, Ambient temperatures, Filter cake, Elevated temperatures, Concentrations.
This paper reports an analytical study conducted to investigate the behaviour of tracers undergoi... more This paper reports an analytical study conducted to investigate the behaviour of tracers undergoing creeping flow between two parallel plates in porous media. A new coupled model for the characterisation of fluid flow and transport of tracers at pore scale is formulated. Precisely, a weak-form solution of radial transport of tracers under convection–diffusion-dominated flow is established using hypergeometric functions. The velocity field associated with the radial transport is informed by the solution of the Stokes equations. Channel thickness as a function of velocities, maximum Reynolds number of each thickness as a function of maximum velocities and concentration profile for different drift and dispersion coefficients are computed and analysed. Analysis of the simulation results reveals that the dispersion coefficient appears to be a significant factor controlling the concentration distribution of the tracer at pore scale. Further analysis shows that the drift coefficient appear...
SPE Nigeria Annual International Conference and Exhibition, 2018
Homotopy analytical method (HAM) is a computational method that provides solution to highly non-l... more Homotopy analytical method (HAM) is a computational method that provides solution to highly non-linear partial differential equations (PDE's) in much similar way as other perturbation and asymptotic techniques. This research work illustrates the benefit of using (HAM) to obtain a type curve over conventional log approximation of dimensionless variables. From such type curves, average reservoir properties, porosity and permeability were obtained from dimensionless equations. This type curve was obtained by matching plots from HAM solution and well test data. The HAM is independent of small/large parameter and can be used to obtain analytical solutions to highly nonlinear partial differential equations unlike other analytical and asymptotic techniques applies to weakly nonlinear problems. The HAM solution gives values of reservoir pressure distribution as a continuous function of time and converges easily for large reservoirs (rD =380) typically. One advantage of HAM is that it provides a means to ensure convergence of series solution by introduction of convergent control parameter. Plots of reservoir pressure distribution as a function of time curves were also obtained and extrapolated for easy matching and were matched with the type curve. Dimensionless pressure and time were used to compute average porosity and permeability which were found to be 1.51md permeability and 1.81% porosity. Computer program was developed for computations using MATLAB and further analysis of data using EXCEL. From the match points obtained, reservoir properties were estimated.
This investigation demonstrates the use of acentric factor as the third parameter in a correspond... more This investigation demonstrates the use of acentric factor as the third parameter in a corresponding states correlation for compressibility factors and a discussion of their application to three different types of gas reservoir.A correlation is presented which provides compressibility factors based on Hall – Yarborough equation of states for use in both two – phase and single-phase hydrocarbon systems. The modified Hall - Yarborough equation employs the acentric factor as an additional parameter to improve its accuracy. This modified equation is as simple as the original form, yet achieves substantially better prediction accuracy, especially at higher pressure.The correlation is based on hydrocarbon compressibility determinations from twenty-two hydrocarbon samples taken from three different types of reservoir systems. Out of the data used 67 percent were from dew point or retrograde gas condensate and bubble point or dissolved gas reservoir, 33 percent were from single phase gas re...
ABSTRACT Filtrate losses and filter cake properties of drilling fluids are of concern in the oil ... more ABSTRACT Filtrate losses and filter cake properties of drilling fluids are of concern in the oil industry because they alter near wellbore permeability and can reduce well productivity. Therefore, it is desirable to accurately characterize filtration process during oil well drilling. A mathematical model for analyzing mud filtration in deviated wells was developed in this study. The model determined solid pressure distribution within cake, cake thickness, cumulative volume of filtrate, and extent of invasion under different conditions. Results show assumptions of isotropy in previous studies greatly overestimate the magnitude of the damage. It was also confirmed that mud filtration tend to be higher in deviated than in vertical wells. The model was validated with experimental data.
Research has shown that faults, especially sealing faults, have become a barrier to flow. Flow di... more Research has shown that faults, especially sealing faults, have become a barrier to flow. Flow diagnostics, on the other hand, are straightforward and controlled numerical flow experiments that are performed to examine a reservoir model, build links and offer rudimentary volume estimates as well as to quickly produce a qualitative representation of the reservoir's flow patterns. To evaluate, assess, and validate reservoir models and production scenarios, the 'diagnostics' module in the Matlab Reservoir Simulation Toolbox (MRST) provides a computationally less expensive alternative to running fully featured multiphase simulations. This is done to determine qualitatively regions for well placement to maximize hydrocarbon recovery. Monitoring flow fields, timelines, and tracers-neutral particles in the fluid that flow with the fluid-are all part of flow diagnostics. These techniques are used to determine volumetric communication between a pair of injector-producer wells, as well as flow patterns between injection-production wells and the arrival time between them. To create the grid, the simulation schedule, the wells, upscaling, arrival time computation, and flow diagnostics (drainage and sweep regions) were all done using the Matlab reservoir simulation toolbox (MRST) package by "Makemodel 3" on the data obtained from "SPE 10 th comparative solution project" on the MRST package. This was done for a homogeneous anisotropic faulted porous medium. The simulation runs for about 473,739 milliseconds on a fine grid having 20040 active cells while in the coarse model with faster computational time of about 200 seconds, 112 milliseconds. At the early stages of the reservoir bottom-hole pressure for injector I1(about 7000psia) and three producers P1, P2 and P3 remains constant over time (about 3600psia) thanks to pressure support by I1. The extent of residence time after 10 years for the fine, coarse and more coarser model is that fluid element find it easier to transverse through the fault line from I1 to P1, P2 then P3 which takes lesser time than crossing across two intersecting faults, It can also be seen that the sweep efficiency of the fine grid is more effective than the coarse grid. Finally, it has been seen clearly that the fine grid model gives more accurate details but slower computational time while the coarse model which is less accurate but with faster computational time.
Sand production due to result of unconsolidated grains in wellbore formations, as lead to many ad... more Sand production due to result of unconsolidated grains in wellbore formations, as lead to many adverse effect, such as plugging, accumulation in surface equipment, increase in skin and tubing roughness. Sensitivity analysis using PROSPER software was run on different well parameters, (tubing roughness, skin) and under free gas effect for an open hole completion to predict effect of sand production in life of the well. The tubing and skin analysis shows a decline in well flow potential across the years, due to sand production. The future performance indicate sand control remedy must be deploy to maintain and revive the well to it optimum flow potential. Analysis on free gas effect was used to determine the highest free gas value under the reservoir condition for the well optimum production. (3.5-4.023) MMscf/day gave the optimal flow potential for the well. This analysis shows the amount and condition of free gas in the well before the effect of sand production. INTRODUCTION Sand prediction model have the capability to indicate whether initial sand production may take place somewhere during the lifetime of an oil gas field. Prediction of maximum sand-free production rate provides information for sand-control decisions and allows maximization of rate in those wells that are completed without sand control. In this paper, filed data will be used for modelling and making this predictions. A significant proportion of the world gas reserves is contained in weakly consolidated sandstone reservoirs and hence is prone to sand production. Material degradation is a key process leading to sanding. Drilling operations, cyclic effects of shut-in and start-up, operational conditions, reservoir pressure depletion, and strength-weakening effect of water may gradually lead to sandstone degradation around the perforations and boreholes. High pressure gradient due to fluid flow also facilitates the detachment of sand particles. In addition, fluid flow is responsible for the transport and production of cohesionless sand particles or detached sand clumps to the wellbore. Sand production is the cause of many problems in the oil industry and it affects the completion adversely. These problems include, but are not limited to, plugging the perforations or production liner, wellbore instability, failure of sand control completions Sand-production problems can be experienced in various ways. In conventional oil wells, transient sand production, where the sand production rate declines rapidly with time, is frequently experienced during the clean-up period after processes such as perforating or acidizing, after rapid bean-up of production, or after water breakthrough. It is assumed that sand production in these cases is merely the removal of weakened or sheared and dilated sand. However, there are different " types " of sand-production behavior. Conventional-oil sand production has been classified on the basis of distinct reservoir evolution stages: The early transient sand-production period, when some of the perforation-induced damage has been removed and the cavities may have a zone of reduced permeability around them, leading to a steep exit gradient. A stable production period with enlarged cavities, when the damaged zone and the permeability impairment have been removed. A general increase in sand influx after a water-cut increase, a process that is considered to be related to capillary forces and is a type of flow-rate-induced sand production.
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Papers by Ibrahim Ayuba