A Comparative Study of Hydraulic Models for Foam Drilling

Abstract

Compared to conventional (incompressible) drilling fluids, relatively little is known about the hydraulic and rheological properties of foamed drilling fluids. The complex flow mechanisms involved in compressible drilling fluid circulation make determination of the optimum combination of liquid and gas injection rates very difficult. Modelling of foam rheology is the key issue in hydraulic design, in order to predict the bottom-hole pressure accurately, and to optimize the different controllable variables for effective cutting transport performance.The University of Tulsa's low-pressure ambient temperature flow loop has been recently modified to accommodate foam flow. The flow loop permits foam flow through 0.0508 m (2 in.), 0.0762 m (3 in.), 0.1016 m (4 in.) diameter pipes, and a 0.2032 m (8 in.) by 0.1143 m (4 1 /2 in.) annular section. Preliminary experiments have been conducted, in which pressure losses were measured for different foam qualities. Measured parameters were gas/liquid flow rates, pressure, differential pressure loss, and temperature.Statistical analysis was carried out to see the degree of fit provided by Bingham plastic, power law, and yield power law models for the generalized foam flow curve data.A comparative study was conducted to investigate the predictive ability of the available foam hydraulic models. Models presented by Beyer et al. (1972), Reidenbach et al. (1986), Sanghani and Ikoku (1983), Gardiner et al. (1988 and Valko and Economides (1992) were used to estimate the frictional pressure losses during the flow of foam in horizontal pipes. Comparison of the model predictions with experimental pressure loss values show that model predictions of frictional pressure losses can be different from the actual values by 2 to 250 %. FIGURE 20: Error analysis of foam hydraulic models (70% quality). FIGURE 22: Error analysis of foam hydraulic models (90% quality).FIGURE 21: Error analysis of foam hydraulic models (80% quality).

Rheological behavior of oil-based drilling foams

“…Pipe viscometers were used in most of these studies to characterize flow behavior of foams. Other studies (Ozbayoglu et al, 2000;Ahmed et al, 2003b) focused on topics like hydraulic performance of foam under different conditions. In addition, rheological properties of foams with different viscosifying additives were investigated (Harris, P.S.…”

“…This specific (critical) point depends up on the liquid phase composition and its rheological properties. Ozbayoglu et al (2000) investigated different foam hydraulic models (Beyer et al, 1972;Blauer and Kohlhaas 1974;Sanghani and Ikoku 1983;Gardiner et al, 1998;and Valko and Economides 1992) developed over the years to assess their accuracy. Model predictions were compared with their experimental results.…”

“…Moreover, they pointed out that the rheology of intermediate quality (70 and 80%) foams can be best described using power law model while high-quality foam (90%) can be best represented by Bingham plastic model. Some studies (David and Marseden, 1968;Ahmed et al, 2003a;and Ozbayoglu et al, 2000) considered wall slip in rheology characterization and hydraulic model formulation. The formation of a thin liquid layer at the pipe wall is expected to act as lubricant during the foam fluid flow.…”

Numerical Modelling of Cuttings Transport with Foam in Inclined Wells

“…Ozbayoglu et al [85] carried out a comparative study of the foam hydraulic models. They suggested that foams can be modeled as a power law fluid when the foam quality is 70-80% and as a Bingham plastic fluid when the foam quality is 90%.…”

Using foam in horizontal well drilling: A cuttings transport modeling approach

“…Ozbayoglu et al (2002) showed that, no bbestQ rheological model existed to explain the rheological behavior of foam for all quality ranges. Therefore, generalized rheological model parameters, N and KV, are preferred to explain foam behavior in this study, where N and KV are functions of foam quality as well as the conduit geometry where the flow takes place.…”