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The effective determination of pressure losses depends on accurate knowledge of the drilling fluid rheology. As the fluid circulates deeper around the wellbore, its rheological behavior undergoes significant alterations due to the variations in downhole conditions encountered. The present study investigates the effects of the rheological properties of Yield-power law fluid at various pressures and temperatures on annular pressure losses and velocity profiles. Simulations were performed using Computational Fluid Dynamics to examine the fluid flow in turbulent and laminar regimes. Comparison between numerical, experimental and slot approximation model results showed a good agreement. Results indicated that pressure losses have reduced in both regimes with increasing temperature, at a constant pressure. However the pressure has the opposite effect at a constant temperature. For a drilling fluid flow velocity of 1 m/s, the elevation of temperature from 25 °C to 90 °C, decreases the pressure drop gradient by (31% to 48%) at low and high- pressure conditions respectively. Whereas, the influence of increasing pressure on pressure losses is more apparent at 25 °C. Earlier transition from laminar to turbulent is observed with temperature rise. Therefore, the temperature effect on pressure losses in the turbulent region; is shown for different Generalized Reynolds numbers. [ABSTRACT FROM AUTHOR]

It is well known that the type of drill pipe motion has an important effect on the cuttings transportation process and pressure loss gradient in the annular space, in particular for horizontal and deviated wells. For that, it is needed to understand more about the effect of planetary motion on the pressure loss gradient during circulation of the drilling mud in the bottom hole of explored wells. In the present paper, the influence of the drill pipe planetary motion on the pressure loss gradient of a mixture (Ostwald-de Waele fluid with solid particles) in a turbulent regime during its circulation through an annular space is evaluated for different drilling parameters including eccentricity, rate of penetration, and solid particles size. In addition, the effect of drill pipe planetary motion for various conditions of temperature and pressure is evaluated for two types of muds water-based and oil-based. The numerical analysis revealed that an angular speed of 120 rpm of planetary motion can be considered as an optimal value in terms of pressure loss gradient. In addition, it was observed that the effect of the planetary motion on the pressure loss gradient depends mainly on the fluid temperature for both types of mud. [ABSTRACT FROM AUTHOR]

The long‐distance pipeline transportation of heavy crudes demands optimal pumping procedures to abate overhead expenditures in the midstream phase. This can be facilitated by reducing both the oil viscosity and the frictional losses induced by the turbulent flow zone. The dualistic approach of reducing both viscosity and drag requires the optimization of several parameters such as concentrations and types of diluents and additives. This manuscript critically reviews various technologies being undertaken to facilitate the pipeline transportation of heavy crude oils by highlighting the technique of dilution coupled with the addition of drag reducing agents (DRA). DRA such as surfactants, nanoparticles, bio‐additives, polymers, and fibres are blended with the diluted crudes to suppress the proliferation of turbulent eddies which in turn assist in pumping the oil at a higher flow rate under constant pressure conditions. Several investigations have reported that drag reduction is significantly enhanced by varying the molecular structure of the DRA. In addition, an optimum flow rate coupled with a specific surfactant concentration at an ideal temperature can significantly reduce head losses and pumping expenditures. Further research is imperative to study the effect of the polymer structure with respect to the induced shear degradation and dissolution behavior of the crude. [ABSTRACT FROM AUTHOR]

A correct prediction of drilling fluid pressure drop is considered as a key parameter to carry out an efficient drilling operation and avoid non-productive time (NPT) during enrollment of the process. In this paper, a numerical approach is employed to analyze frictional pressure loss of Herschel-Bulkley (yield power-law) fluid flowing through an annular geometry in which the inner pipe makes a helical buckling motion in laminar and turbulent regimes. Results showed that rotation of the helically-buckled inner pipe induces a decrease of 10% and 6% of the pressure loss gradient of the Herschel-Bulkley fluid in the laminar regime for the helical pitch lengths of 6.9 m and 10 m, respectively. Also, increasing the pitch length of a helically-shaped inner pipe reduces the pressure loss gradient, particularly for low angular speeds. Moreover, the helical pitch length increment from 6.9 m to 10.7 m slightly affects the pressure loss gradient for the turbulent regime. [ABSTRACT FROM AUTHOR]

This paper aims to estimate surge pressure resulting from the flow of a Herschel-Bulkley fluid through concentric annuli during tripping operations. A semi-analytical model which includes new constraints to avoid non-physical solutions was developed then solved numerically . Moreover, a numerical model was implemented using finite difference method for which accurate solutions were obtained. Besides, the commercial software (Ansys-Fluent 19R3) was employed. The results are compared with existing experimental data from literature where a good agreement is observed with a maximum average relative error of 4% and 7.8% for the two studied drilling fluids, respectively. These models were successfully extended to power-law fluids. On the other hand, numerical results were collected by varying the relevant drilling parameters. The outputs indicated that the increase in the pipe tripping velocity causes an increase of the surge pressure independently of the parameter of interest, however, the rate of increase changes from one parameter to another. Based on this parametric study, a surrogate model using the Random Forest algorithm is constructed. This model predicts surge and swab pressures without requiring cumbersome numerical calculations. The model predictions have shown a satisfactory matching with an R2 equals to 0.99 for both training and test data. [ABSTRACT FROM AUTHOR]

Among consequences that can be induced by a non-uniform distribution of the stress and other causes during the drilling process is the elliptical shape of the well and consideration of this effect would improve the accuracy of the drilling fluid hydrodynamics prediction. In the present work, the elliptical shape of the annular space is simplified to apply the slot model taking into account the rotation of the inner cylinder. Moreover, the Slot model results are compared with the experimental data, as well as, with the CFD outcomes where a reasonable concordance is observed, especially for low ratios of the major and minor semi-axis. Also, the CFD results are validated with the experimental data from the flow loop setup. We concluded that the increase of the major and minor semi-axis ratio of the elliptical annulus results in a linear increase of the Ostwald-de Waele frictional pressure loss in the laminar regime for all considered rotation speeds of the inner cylinder. In addition, the increase of the eccentricity from 0 to 0.75 has a positive effect where the frictional pressure loss is decreased by almost 28% for all rotation speeds for the elliptical annulus ( η = 1.2). [ABSTRACT FROM AUTHOR]