scholarly journals The Effect of Thixotropy on Pressure Losses in a Pipe

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6165
Author(s):  
Eric Cayeux ◽  
Amare Leulseged
Keyword(s):  
A Priori ◽  
Solid Material ◽  
Drilling Fluids ◽  
Pressure Gradients ◽  
Pressure Losses ◽  
Turbulent Flow Regime ◽  
Thixotropic Behavior ◽  
Actual Response ◽  
Viscous Pressure ◽  
High Bulk

Drilling fluids are designed to be shear-thinning for limiting pressure losses when subjected to high bulk velocities and yet be sufficiently viscous to transport solid material under low bulk velocity conditions. They also form a gel when left at rest, to keep weighting materials and drill-cuttings in suspension. Because of this design, they also have a thixotropic behavior. As the shear history influences the shear properties of thixotropic fluids, the pressure losses experienced in a tube, after a change in diameter, are influenced over a much longer distance than just what would be expected from solely entrance effects. In this paper, we consider several rheological behaviors that are relevant for characterizing drilling fluids: Collins–Graves, Herschel–Bulkley, Robertson–Stiff, Heinz–Casson, Carreau and Quemada. We develop a generic solution for modelling the viscous pressure gradient in a circular pipe under the influence of thixotropic effects and we apply this model to configurations with change in diameters. It is found that the choice of a rheological behavior should be guided by the actual response of the fluid, especially in a turbulent flow regime, and not chosen a priori. Furthermore, thixotropy may influence pressure gradients over long distances when there are changes of diameter in a hydraulic circuit. This fact is important to consider when designing pipe rheometers.

scholarly journals Measurement of Drilling Fluid Rheology and Modeling of Thixotropic Behavior

2019 ◽  
Vol 29 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Hans Joakim Skadsem ◽  
Amare Leulseged ◽  
Eric Cayeux
Keyword(s):  
Shear Rate ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Rheological Characterization ◽  
Pressure Losses ◽  
Rate Step ◽  
Thixotropic Behavior ◽  
Pump Pressure ◽  
Static Conditions ◽  
Fluid Rheology

Abstract Drilling fluids perform a number of important functions during a drilling operation, including that of lifting drilled cuttings to the surface and balancing formation pressures. Drilling fluids are usually designed to be structured fluids exhibiting shear thinning and yield stress behavior, and most drilling fluids also exhibit thixotropy. Accurate modeling of drilling fluid rheology is necessary for predicting friction pressure losses in the wellbore while circulating, the pump pressure needed to resume circulation after a static period, and how the fluid rheology evolves with time while in static or near-static conditions. Although modeling the flow of thixotropic fluids in realistic geometries is still a formidable future challenge to be solved, considerable insights can still be gained by studying the viscometric flows of such fluids. We report a detailed rheological characterization of a water-based drilling fluid and an invert emulsion oilbased drilling fluid. The micro structure responsible for thixotropy is different in these fluids which results in different thixotropic responses. Measurements are primarily focused at transient responses to step changes in shear rate, but cover also steady state flow curves and stress overshoots during start-up of flow. We analyze the shear rate step change measurements using a structural kinetics thixotropy model.

Annular Frictional Pressure Losses During Drilling—Predicting the Effect of Drillstring Rotation

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Arild Saasen
Keyword(s):  
Rheological Properties ◽  
Pressure Loss ◽  
Drilling Fluid ◽  
Axial Flow ◽  
Drilling Fluids ◽  
Unstable Flow ◽  
Pressure Losses ◽  
Shear Dependent Viscosity ◽  
Water Based ◽  
Dependent Viscosity

Controlling the annular frictional pressure losses is important in order to drill safely with overpressure without fracturing the formation. To predict these pressure losses, however, is not straightforward. First of all, the pressure losses depend on the annulus eccentricity. Moving the drillstring to the wall generates a wider flow channel in part of the annulus which reduces the frictional pressure losses significantly. The drillstring motion itself also affects the pressure loss significantly. The drillstring rotation, even for fairly small rotation rates, creates unstable flow and sometimes turbulence in the annulus even without axial flow. Transversal motion of the drillstring creates vortices that destabilize the flow. Consequently, the annular frictional pressure loss is increased even though the drilling fluid becomes thinner because of added shear rate. Naturally, the rheological properties of the drilling fluid play an important role. These rheological properties include more properties than the viscosity as measured by API procedures. It is impossible to use the same frictional pressure loss model for water based and oil based drilling fluids even if their viscosity profile is equal because of the different ways these fluids build viscosity. Water based drilling fluids are normally constructed as a polymer solution while the oil based are combinations of emulsions and dispersions. Furthermore, within both water based and oil based drilling fluids there are functional differences. These differences may be sufficiently large to require different models for two water based drilling fluids built with different types of polymers. In addition to these phenomena washouts and tool joints will create localised pressure losses. These localised pressure losses will again be coupled with the rheological properties of the drilling fluids. In this paper, all the above mentioned phenomena and their consequences for annular pressure losses will be discussed in detail. North Sea field data is used as an example. It is not straightforward to build general annular pressure loss models. This argument is based on flow stability analysis and the consequences of using drilling fluids with different rheological properties. These different rheological properties include shear dependent viscosity, elongational viscosity and other viscoelastic properties.

Mechanism of reduced maximum expiratory flow in methacholine-induced bronchoconstriction in dogs

1983 ◽  
Vol 55 (3) ◽  
pp. 897-912 ◽  
Author(s):  
S. N. Mink
Keyword(s):  
Wave Speed ◽  
Cross Sectional ◽  
Pressure Losses ◽  
Lung Capacity ◽  
Group I ◽  
Maximum Expiratory Flow ◽  
Pressure Area ◽  
Expiratory Flow ◽  
Group Ii ◽  
Viscous Pressure

Airway sites of flow limitation [“choke points” (CP)] were identified during forced deflation in open-chest dogs before (C) and after (B) bronchoconstriction was produced by nebulizing a solution of methacholine chloride into their airways. CP were identified in two respective groups. In group I (n = 8) a retrograde catheter was used to locate CP and in the other a Pitot static tube (group II, n = 5), CP were identified at multiple lung volumes (VL) over the lower one-half of total lung capacity. Both groups showed similar findings at each condition. At B, corresponding values of maximum expiratory flow (Vmax) at each VL decreased to about 10% of those at C. Movement of CP relative to their original location varied at each VL and, especially at the lower VL, showed little peripheral movement. In group I, equal pressure points were also measured and were found to move peripherally at all the measured VL. In group II, cross-sectional area (A*) and airway compliance (K) at CP were estimated. During bronchoconstriction, A* decreased at the respective VL, and airways became less compliant. The reduction in Vmax could be explained in terms of changes in A* and K as described by wave-speed theory, and Vmax decreased because A* decreased. The decrease in A* was related in part to an increase in viscous pressure losses that reduced total pressure at CP and also in part to a change in the pressure-area behavior of bronchi at CP. Their relative effects on reducing A* and Vmax were examined.

scholarly journals Uncertainties quantification and modelling of different rheological models in estimation of pressure losses during drilling operation

2018 ◽  
Vol 7 (2) ◽  
pp. 694 ◽  
Author(s):  
Anawe P. A. L ◽  
Folayan J. Adewale
Keyword(s):  
Power Law ◽  
Averaging Method ◽  
Graphical Method ◽  
Flow Behavior ◽  
Drilling Fluids ◽  
Flow Behavior Index ◽  
Rheological Models ◽  
Pressure Losses ◽  
Pump Pressure ◽  
Behavior Index

The determination of pressure losses in the drill pipe and annulus with a very high degree of precision and accuracy is sacrosanct for proper pump operating conditions and correct bit nozzle sizes for maximum jet impact and forestalling of possible kicks and eventual blow outs during drilling operation. The two major uncertainties in pump pressure estimation that are being addressed in this research work are the flow behavior index (n) and the consistency index factor (k). It is in this light that the accuracy of various rheological models in predicting pump pressure losses as well as the uncertainties associated with each model was investigated. In order to come by with a decisive conclusion, two synthetic based drilling fluids were used to form synthetic muds known as sample A and B respectively. Inference from results shows that the Newtonian model underestimated the pump pressure by 78.27% for sample A and 82.961% by for sample B. While the Bingham plastic model overestimated the total pump pressure by 100.70% for sample A and 48.17% for sample B. Three different power law rheological model approaches were used to obtain the flow behavior index and consistency factor of the drilling fluids. For the power law rheological model approaches, an underestimation error of 23.5743% was encountered for the Formular method for sample A while the proposed consistency index averaging method reduces the error to 14.9306%. The Graphical method showed a reasonable degree of accuracy with underestimation error of 5.6435%. Sample B showed an underestimation error of 47.8234% by using the power law formula method while the Consistency averaging method reduced the error to 20.7508. The graphical method showed an underestimation error of 0.4318%.

scholarly journals Annular Frictional Pressure Losses for Drilling Fluids

2021 ◽  
Author(s):  
Arild Saasen ◽  
Jan David Ytrehus
Keyword(s):  
Drilling Fluids ◽  
Pressure Losses

scholarly journals Thixotropic evaluation of bentonitic clay dispersions modified with nonionic surfactants for organic drilling fluids

Cerâmica ◽  
2018 ◽  
Vol 64 (371) ◽  
pp. 425-430
Author(s):  
I. A. Silva ◽  
I. D. S. Pereira ◽  
F. K. A. Sousa ◽  
R. R. Menezes ◽  
G. A. Neves ◽  
...  
Keyword(s):  
Nonionic Surfactants ◽  
Drilling Fluids ◽  
X Ray Diffraction ◽  
Performance Factors ◽  
Bentonitic Clay ◽  
Colloid Science ◽  
Organophilic Clays ◽  
Thixotropic Behavior ◽  
Low Toxicity ◽  
Overall Performance

Abstract The use of nonionic surfactants to modify the surface of bentonite is still quite restricted, although many advantages of that method can be found in the literature, like superior stability and low toxicity. On the other hand, problems involving the fluidity and viscosity of dispersions used in organic drilling fluids have become more and more challenging to colloid science. Therefore, the present study had the purpose of assessing the thixotropic behavior of dispersions of Brazilian bentonite organophilizated with nonionic surfactants for use in organic drilling fluids. Bentonite samples were organophilizated by a combination of two nonionic surfactants, being the process evaluated by X-ray diffraction and thermogravimetric analysis, in which the amount of nonionic surfactants incorporated was quantified. Fluid evaluation followed current standards. The flow curves of the organophilic clays revealed pseudoplastic behavior and the presence of hysteresis, which suggested thixotropy, with a relation between the thixotropy and the apparent viscosity of the final dispersions. Most of the process parameters evaluated showed significant effects on the value of d001 and the overall performance. Factors like clay type and organophilization method also directly affect the thixotropic behavior of dispersions. One of the samples can be considered promising for use in organic drilling fluids.

Modeling Lost Circulation Through Drilling-Induced Fractures

SPE Journal ◽  
2017 ◽  
Vol 23 (01) ◽  
pp. 205-223 ◽  
Author(s):  
Yongcun Feng ◽  
K. E. Gray
Keyword(s):  
Loss Rate ◽  
Fluid Loss ◽  
Operational Parameters ◽  
Fracture Width ◽  
Pressure Losses ◽  
Lost Circulation ◽  
Wellbore Pressure ◽  
Induced Fractures ◽  
Wellbore Strengthening ◽  
Viscous Pressure

Summary Previous lost-circulation models assume either a stationary fracture or a constant-pressure- or constant-flowrate-driven fracture, but they cannot capture fluid loss into a growing, induced-fracture driven by dynamic circulation pressure during drilling. In this paper, a new numerical model is developed on the basis of the finite-element method for simulating this problem. The model couples dynamic mud circulation in the wellbore and induced-fracture propagation into the formation. It provides estimates of time-dependent wellbore pressure, fluid-loss rate, and fracture profile during drilling. Numerical examples were carried out to investigate the effects of several operational parameters on lost circulation. The results show that the viscous pressure losses in the wellbore annulus caused by dynamic circulation can lead to significant increases in wellbore pressure and fluid loss. The information provided by the model (e.g., dynamic circulation pressure, fracture width, and fluid-loss rate) is valuable for managing wellbore pressure and designing wellbore-strengthening operations.

Effect of Drillstring Deflection and Rotary Speed on Annular Frictional Pressure Losses

2013 ◽  
Author(s):  
Oney Erge ◽  
Mehmet E. Ozbayoglu ◽  
Stefan Z. Miska ◽  
Mengjiao Yu ◽  
Nicholas Takach ◽  
...  
Keyword(s):  
Pressure Loss ◽  
Drilling Fluid ◽  
Flow Behavior ◽  
Hole Drilling ◽  
Accurate Estimation ◽  
Drilling Fluids ◽  
Limited Information ◽  
Pressure Losses ◽  
Gas Drilling ◽  
Fracture Pressure

Keeping the drilling fluid equivalent circulating density in the operating window between the pore and fracture pressure is a challenge, particularly when the gap between these two is narrow, such as in offshore applications. To overcome this challenge, accurate estimation of frictional pressure loss in the annulus is essential, especially for multilateral, extended reach and slim hole drilling applications usually encountered in shale gas and/or oil drilling. A better estimation of frictional pressure losses will provide improved well control, optimized bit hydraulics, a better drilling fluid program and pump selection. Field and experimental measurements showed that pressure loss in the annulus is strongly affected by the pipe rotation and eccentricity. Eccentricity will not be constant throughout a wellbore, especially in highly inclined and horizontal sections. In an actual wellbore, because of rotation speed and the applied weight, some portion of the drillstring will undergo compression. As a result, variable eccentricity will be encountered. At high compression, the drillstring will buckle, resulting in sinusoidal or helical buckling configurations. Most of the drilling fluids used today show highly non-Newtonian flow behavior, which can be characterized using the Yield Power Law (YPL). Nevertheless, in the literature, there is limited information and research on YPL fluids flowing through annular geometries with the inner pipe buckled, rotating, and eccentric. Furthermore, there are discrepancies reported between the estimated and measured frictional pressure losses with or without drillstring rotation of YPL fluids, even when the inner pipe is straight. The major focus of this project is on a horizontal well setup with drillstring under compression, considering the influence of rotation on frictional pressure losses of YPL fluids. The test matrix includes flow through the annulus for various buckling modes with and without rotation of the inner pipe. Sinusoidal, helical and transition from sinusoidal to helical configurations with and without the rotation of the drillstring are investigated. Results show a substantial difference of frictional pressure losses between the non-compressed and compressed drillstring. The drilling industry has recently been involved in incidents that show the need for critical improvements for evaluating and avoiding risks in oil/gas drilling. The information obtained from this study can be used to improve the control of bottomhole pressures during extended reach, horizontal, managed pressure, offshore and slim hole drilling applications. This will lead to safer and enhanced optimization of drilling operations.

A Simple Predictive Method of Steam Pipe Forces From Stop Valve Closure

2004 ◽  
Author(s):  
Kellie Norton ◽  
F. J. Moody
Keyword(s):  
High Speed ◽  
Initial Conditions ◽  
Pressure Gradients ◽  
Valve Closure ◽  
Stop Valve ◽  
Pressure Losses ◽  
Predictive Method ◽  
Time Space ◽  
Piping Systems ◽  
Steam Pipe

Piping systems that are subject to a fast closing valve are susceptible to large steamhammer forces. The steamhammer force is a result of high-speed pressure waves propagating through the pipe that create sizeable pressure gradients in the pipe. This paper introduces a simple predictive method of the pipe forces induced by the pressure gradients in a steam pipe resulting from stop valve closure. The case of instant valve closure is also examined for comparison. The assumptions in this analysis are that the stop valve closure is linear, the pressure losses from any bends in the pipe can be ignored, the downstream pressure is constant, the steam flow is at a constant pressure, and finally the pipe walls are rigid at a constant radius. The method introduces functions that are constant along diagonal lines on the time-space graph. The pressure and velocity along these lines can be computed from the initial conditions and boundary conditions. Finally, the pipe forces are calculated using the pressures in the targeted regions of the pipe.

Sign in / Sign up

Export Citation Format

Share Document