Dynamical feature of particle dunes in Newtonian and shear-thinning flows: Relevance to hole-cleaning in pipe and annulus (original) (raw)
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Energies
Water-based polymer drilling fluids are commonly used for drilling long horizontal wells where eliminating the drilling fluid-related formation damage and minimizing the environmental impact of the drilling fluids are the main concerns. An experimental study was conducted to investigate the turbulent flow of a polymer fluid over a stationary sand bed deposited in a horizontal pipeline. The main objectives of the study were to determine the effects of sand particle size on the critical velocity required for the onset of the bed erosion and the near-wall turbulence characteristics of the polymer fluid flow over the sand bed. Industrial sand particles having three different size ranges (20/40, 30/50, 40/70) were used for the experiments. The particle image velocimetry (PIV) technique was used to determine instantaneous local velocity distributions and near-wall turbulence characteristics (such as Reynolds stress, axial and turbulence intensity profiles) of the polymer fluid flow over t...
2018
Water-based polymer drilling fluids are commonly used for drilling long horizontal wells where eliminating the drilling fluid-related formation damage and minimizing the environmental impact of the drilling fluids are the main concerns. An experimental study was conducted to investigate the turbulent flow of a polymer fluid over a stationary sand bed deposited in a horizontal pipeline. The main objectives of the study were to determine the effects of sand particle size on the critical velocity required for the onset of the bed erosion and the near-wall turbulence characteristics of the polymer fluid flow over the sand bed. Industrial sand particles having three different size ranges (20/40, 30/50, 40/70) were used for the experiments. The particle image velocimetry (PIV) technique was used to determine instantaneous local velocity distributions and near-wall turbulence characteristics (such as Reynolds stress, axial and turbulence intensity profiles) of the polymer fluid flow over the stationary sand bed under turbulent flow conditions. The critical velocity for the onset of the particle removal from a stationary sand bed using a polymer fluid flow was affected by the sand particle size. The critical velocity required for the particle removal from the bed deposits did not change monotonously with the changing particle size. When polymer fluids were used for hole cleaning, the particle size effect on the critical velocity varied (i.e., critical velocity increased or decreased) depending on the relative comparison of the sand particle size with respect to the thickness of the viscous sublayer under turbulent flow condition.
Experimental and Computational Multiphase Flow
The flow dynamics in pipes is a very complex system because it is largely affected by flow conditions. The transport of crude oil in pipelines within unconsolidated petroleum reservoirs is associated with presence of solid particles. These particles are often transported as dispersed phases during crude oil production and are therefore detrimental to the pipe surface integrity. This could lead to the occurrences of crevice corrosion due to pipe erosion. In relation to the above discussion, this paper is aimed at analyzing crude oil dynamics during flow through pipeline and identifying erosion hotspot for different pipe elbow curvatures. Reynolds Averaging Navier-Stokes (RANS) and Particle Tracing Modeling (PTM) approach were used. The focus is to simulate fluid dynamics and particle tracing, respectively. Post-processed results revealed that the fluid velocity magnitude was relatively high at the region with minimum curvature radius. The maximum static pressure and turbulence dissipation rate were experienced in areas with low-velocity magnitude. Also, the rate of erosive wear was relatively high at the elbow and the hotspot varied with pipe curvature. The particle flow rate, mass, and size were varied and it was found that erosion rate increased with an increase in particle properties.
Frontiers in Energy, 2018
Imaging with high definition video camera is an important technique to visualize the drilling conditions and to study the physics of complex multiphase flow associated with the hole cleaning process. The main advantage of visualizing multiphase flow in a drilling annulus is that the viewer can easily distinguish fluid phases, flow patterns and thicknesses of cutting beds. In this paper the hole cleaning process which involves the transportation of cuttings through a horizontal annulus was studied. The two-phase (solid-liquid) and the three-phase (solid-liquid-gas) flow conditions involved in this kind of annular transportation were experimentally simulated and images were taken using a high definition camera. Analyzing the captured images, a number of important parameters like velocities of different phases, heights of solid beds and sizes of gas bubbles were determined. Two different techniques based on an image analysis software and MATLAB coding were used for the determinations. The results were compared to validate the image analyzing methodology. The visualization technique developed in this paper has a direct application in investigating the critical conditions required for efficient hole cleaning as well as in optimizing the mud program during both planning and operational phases of drilling. Particularly, it would be useful in predicting the cuttings transport performance, estimating solid bed height, gas bubble size, and mean velocities of bubbles/particles.
Straight and coiled tubing are frequently used in the petroleum industry in operations such as fracturing, cementing, drilling and perforation. Most of these operations involve flow of slurries during which erosion of tubing is a major problem and its prediction becomes important for the safe and economical execution of oilfield operations. Erosion due to slurry flow depends on a number of factors, several of which are interdependent which makes the process more complex. Various experimental and modeling techniques have been in use to evaluate the erosion resulting from the flow of particles. These experimental and modeling techniques, however, have their limitations due to the deficient experimental data and computational restrictions. This study presents the results of Computational Fluid Dynamics (CFD) analyses conducted on straight and curved tubing sections under various flow conditions and different Newtonian and non-Newtonian base fluids commonly used in the petroleum industry. The particle distribution and shear stress for simulated flow cases have been evaluated and compared to comprehend the nature of particle interaction with the flow boundaries and resulting frictional erosion. The study highlights the effect of lubrication forces and viscosity of the base fluid. Keywords: erosion; coiled tubing; slurry flow; computational fluid dynamics; stimulation; drilling; completion
Particle Induced Erosion Wear in a Sudden Expansion Flow and in a Long Pipe Transporting Crude Oil
Mechanical erosion wear, induced by multiple wall collisions of sand particles, is predicted in long straight pipes used for crude oil transportation. The work investigates the effects of varying particle loading, flow rate and pipe diameter in the induced erosion wear. The Eulerian-Lagrangian code 2-PHASE - developed at the NTUA is used to predict the fluid and particle velocities and calculate the resulting mass removal rate. The accuracy of the code is first validated in a sudden expansion and a wafer choke geometry. The results show that erosion wear in long pipes is very significant at the entrance of the flow, with peak values occurring for a length of approximately twenty-five pipe diameters. The rate of erosion depends mainly on the crude flow rate.
Powder Technology, 2018
In this paper, a comprehensive review of experimental, numerical and artificial intelligence studies on the subject of cuttings settling velocity in drilling muds made by researchers over the last seven decades is brought to the fore. In this respect, 91 experimental, 13 numerical simulations and 7 artificial intelligence researches were isolated, reviewed, tabulated and discussed. A comparison of the three methods and the challenges facing each of these methods were also reviewed. The major outcomes of this review include: (1) the unanimity among experimental researchers that mud rheology, particle size and shape and wall effect are major parameters affecting the settling velocity of cuttings in wellbores; (2) the prevalence of cuttings settling velocity experiments done with the mud in static conditions and the wellbore in the vertical configuration; (3) the extensive use of rigid particles of spherical shape to represent drill cuttings due to their usefulness in experimental visualization, particle tracking, and numerical implementation; (4) the existence of an artificial intelligence technique-multi-gene genetic programming (MGGP) which can provide an explicit equation that can help in predicting settling velocity; (5) the limited number of experimental studies factoring in the effect of pipe rotation and well inclination effects on the settling velocity of cuttings and (6) the most applied numerical method for determining settling velocity is the finite element method. Despite these facts, there is need to perform more experiments with real drill cuttings and factor in the effects of conditions such as drillstring rotation and well inclination and use data emanating therefrom to develop
Adequate cuttings removal from the bottom hole of an oil well to the surface during a rotary drilling is critical for cost-effective drilling. The major factors that describe cuttings transport particularly in vertical sections are fluid effective viscosity and velocity which influence particle settling velocity. Rheological modelling of drilling fluids in oil fields is usually described by Bingham plastic and power law models. These models gain popularity because their specific descriptive parameters are fairly easy to estimate. Standard methods use Fann V-G Meter dial reading at 600 and 300 rpm to determine these rheological parameters. Unfortunately, these points correspond to higher shear rates which seldom prevail during particle settling. This work aims to investigate different shear rates to derive power law rheological parameters and show their influence on the magnitude of effective viscosity and hence settling velocity. The results show that data pair of R600/R3 was the best to predict the full spectrum of the fluid rheogram. Using Chien (1994) correlation, data pair of R200/R100 give the best results for predicting observed settling velocity of a nonspherical particle settling in a static fluid. Data pair of R200/R100 out performs commonly used data pairs (R600/R300, R100/R3 and R6/R3). Furthermore, Using modified Moore correlation with effective viscosity as suggested by Chien obtained excellent predictions with error less than 1% particularly with R600/R100.
Spe Journal, 2020
An experimental study was conducted to determine the influence of fluid elastic properties on the critical velocity, frictional pressure drops, and the turbulent-flow characteristics of polymer-fluid flow over a sand bed deposited in a horizontal pipe. Fluids were prepared using a special technique, which allowed for the alteration of fluid elastic properties while keeping the shear viscosity constant. By conducting experiments under controlled conditions, we were able to quantify the individual effect of the fluid elasticity (independent from shear viscosity) on the critical flow rate for bed erosion and the turbulent-flow characteristics of polymer-fluid flow over the stationary sand bed. Results showed that higher critical velocities were required for the onset of the bed erosion when we use the fluid with higher elasticity.
SPE 128035 A Theoretical and Experimental Analysis of Dynamic Filtration in Drilling Operations
This paper describes a numerical filtration model validated by data obtained from an experimental dynamic filtration loop. The model predicts the filtercake buildup and filtrate flow rate in the drilling process using non-Newtonian muds. It is also able to calculate filtercake properties like permeability and thickness. The equations, written in cylindrical coordinate, are based on the motion and mass conservation equation of the fluid described by Darcy's law. In addition, the permeability and porosity are correlated to the filtercake pressure. The point at which the mud fluid shear rate and the filtercake shear strength are equal defines the filtercake thickness. In the dynamic filtration loop there is a tube with a permeable wall where the carbonate suspension of different sized particles is filtrated. The suspension is homogenized in a tank mixer and pumped using a positive displacement pump. The filtration model was validated through experimental data. In this paper, we discuss the effects of cross-flow velocity and filtration pressure on the filtrate rate and filtercake buildup. The simulated data of filtrate rate and filtercake thickness agreed well with the experimental data. Introduction One of the drilling fluid's basic functions is to exert hydrostatic pressure over the permeable formations to avoid the formation fluid invasion to the well while the drilling operation takes place. The fluid pressure is normally kept above the formation pore pressure to prevent from kick events (formation fluid invasion to the well), that, in some cases, can lead to an uncontrolled influx (blowout). This concept, called overbalanced drilling, is traditionally employed in most of the drilling operations worldwide and in Brazil. As the bit penetrates the reservoir rock, the drilling fluid invades the formation due to the positive pressure differential between the well and the reservoir rock. Portions of the liquid phase of the drilling fluid are lost to the adjacent formation while part of the solids presented in drilling fluid, constituted by particles smaller than the formation pore size, penetrate the rock during the fluid loss period, rapidly plugging the region around the well. Larger particles accumulate on the wellbore walls, initiating an external cake formation. The invasion of fluid and solid particles during this process causes damage to formation around the well. Two invasion mechanisms are notable in the well. The first, called static filtration, occurs when the fluid pumping is interrupted and, from that point on, filtration occurs due to the difference between the hydrostatic pressure in the well and the reservoir pressure. The filtration rates are controlled by the continuously increasing thickness of the filter cake. The other invasion mechanism, called dynamic filtration, occurs when the fluid is pumped through the well. In this process, the cake thickness is resultant from the dynamic equilibrium between solid particles deposition rate and the erosion rate due to the shear stresses generated by the fluid flow in the wellbore. Thus, the filtration rate to the formation tends to stabilize around a certain value while the cake thickness turns constant. Fig.1 illustrates the process. Table 1 shows several authors that studied dynamic and static filtration phenomenon. Modeling and experimental work are listed.