Cuttings Transport with Foam in Horizontal & Highly-Inclined Wellbores

Abstract

fax 01-972-952-9435. AbstractFoams are of considerable interest for annular pressure management in many drilling applications. While foam rheology and hydraulics have been studied in the past, knowledge of cuttings transport with foam is very limited for vertical wells, and even less well understood for horizontal and inclined-well configurations. In this paper, cuttings transport with foam in horizontal and highly-inclined wells is analyzed.Using the principles of mass and linear momentum conservation, a model consisting of three layers (motionless bed -observed in most experiments, moving foam-cuttings mixture and foam free of cuttings) is presented. The model includes seven independent equations and seven unknowns. A computer simulator was developed to solve simultaneously the system of equations for flow velocities, cuttings bed height, slip velocity, the in-situ concentration of flowing cuttings and pressure drop.An extensive experimental program on cuttings transport was conducted using The University of Tulsa Drilling Research Projects' full-scale (8" by 4 ½") flow loop at 70° to 90° inclinations (from vertical). A broad range of annular velocities and cuttings injection rates was investigated using foam qualities of 70% to 90%. Results from the experiments are presented in the form of graphs showing the cuttings bed cross-sectional area and pressure losses vs. foam flow rate. In all experiments, the foam behaved as a pseudo-plastic fluid; foam qualities of 80% and 90% exhibited noticeable wall slip. At a given flow rate and rate of penetration, bed thickness increases with an increase in foam quality. There is little effect of inclination angles in the range of 70°-90°.The experimental data were used to verify results from the simulator. The simulator is capable of estimating bed thickness and pressure drop with an error of less than 20% in most cases.

Cuttings Transport with Foam in Highly Inclined Wells at Simulated Downhole Conditions / Transport urobku wiertniczego przy użyciu piany w silnie nachylonych otworach w symulowanych warunkach w otworze

“…Fig. 12 shows the comparison between the simulator prediction and experimental results from this and previous studies (Duan, 2007;Chen, 2005;Ozbayoglu, 2002). The simulator gives reasonable predictions compared to the experimental measurements within the range of these investigations.…”

“…A Cuttings Transport Simulator was developed based on the experimental results from this study and previous studies, and the modeling approaches are inherited from the work conducted by Duan (2007) and Ozbayoglu (2002). The simulator is capable of predicting cuttings concen- tration, cuttings bed height, frictional pressure loss gradient and foam in situ velocity by taking the input of wellbore geometry, gas and liquid flow rate, pressure, temperature, ROP, drill pipe rotation speed and wellbore inclination angle.…”

“…Using the principles of mass and linear momentum conservation, a model consisting of three layers (motionless bed -observed in most experiments, moving foam-cuttings mixture and foam free of cuttings) was presented (Ozbayoglu et al, 2003). As part of this study, cuttings transport experiments were conducted at inclinations of 70-90 degrees for a wide range of foam flow velocities and ROPs.…”

Flow of power-law fluid in a partially blocked eccentric annulus

“…A number of recent studies (Hansen et al, 1999;Nouri et al, 1993;Nouri and Whitelaw, 1997;Wang et al, 2000;Ozbayoglu, 2002;and Silva and Shah, 2000) conducted on Newtonian and nonNewtonian fluids experimentally evaluated the reduction of frictional pressure loss due to eccentricity. Results confirmed frictional pressure loss reduction of up to 40% due to eccentricity.…”

Advanced Cuttings Transport Study

“…Ozbayoglu et al 20 concluded that there is no "best" model to explain the rheological behavior of foam for all quality ranges. However, the rheology can be better characterized by the Power Law model for 70% to 80% quality foams.…”