Cuttings Transport with Foam in Horizontal & Highly-Inclined Wellbores

Abstract

Cuttings Transport with Foam in Horizontal & Highly-Inclined Wellbores Evren M. Ozbayoglu; Evren M. Ozbayoglu Middle East Technical University Search for other works by this author on: This Site Google Scholar Stefan Z. Miska; Stefan Z. Miska The University of Tulsa Search for other works by this author on: This Site Google Scholar Troy Reed; Troy Reed The University of Tulsa Search for other works by this author on: This Site Google Scholar Nicholas Takach Nicholas Takach The University of Tulsa Search for other works by this author on: This Site Google Scholar Paper presented at the SPE/IADC Drilling Conference, Amsterdam, Netherlands, February 2003. Paper Number: SPE-79856-MS https://doi.org/10.2118/79856-MS Published: February 19 2003 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Ozbayoglu, Evren M., Miska, Stefan Z., Reed, Troy, and Nicholas Takach. "Cuttings Transport with Foam in Horizontal & Highly-Inclined Wellbores." Paper presented at the SPE/IADC Drilling Conference, Amsterdam, Netherlands, February 2003. doi: https://doi.org/10.2118/79856-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE/IADC Drilling Conference and Exhibition Search Advanced Search 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 1/2") 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.IntroductionInefficient cleaning of wellbore may cause severe problems, such as stuck pipe, lost circulation, high torque and drag, loss of control on density and ECDs, poor cement jobs, etc1. Studies on cuttings transport have been in progress since the 1940's. Initial investigations focused on terminal velocity determination for single-phase drilling fluids. Since most of the wells were vertical, terminal velocity was enough to address most of the problems. As interest in directional and horizontal wells increased, studies were shifted to experimental approaches2–4 and mechanistic models trying to explain the cuttings transport phenomenon for all inclination angles. Gavignet and Sobey5 introduced a two-layer model for explaining the cuttings transport phenomenon in an inclined wellbore. Their model consists of a stationary bed, and pure fluid flow in the upper layer. Clark and Bickham6 developed a mechanistic model, based on forces acting on a particle, which they claim was developed for the entire well; i.e., from the bit to the surface. They define three modes for cuttings transport: rolling, lifting and settling. Nguyen and Rahman7 developed a three-layer mechanistic model that is similar to the model developed in the present study. Their model consists of three components; a stationary bed, a dispersed layer and a fluid flow layer. Their model works for different modes of transport, ranging from a stationary bed condition to a fully suspended flow. They did not verify their model with experimental data. However, they do present results from a computer simulator. Later, underbalanced drilling became more important as an essential tool, and the interest expanded to include cuttings transport with multi-phase fluids for inclined and horizontal wells. However, studies conducted on cuttings transport with aerated fluids, especially with foams in highly inclined wells are very limited.Saintpere, et al.8 analyzed hole cleaning with foam in inclined wells using a fluid mechanics approach that ignores inertial effects. They introduced a few dimensionless parameters for describing the fluid rheology, foam properties, flowing time, etc. They observed the worst hole-cleaning performance at angles of 40° to 60°. Martins, et al.9 experimentally studied effective hole cleaning with foam. They developed empirical equations to predict bed erosion in horizontal wells as a function of foam quality and Reynolds number. Keywords: experimental data, upstream oil & gas, grid, concentration, directional drilling, determination, interfacial shear stress, foam quality, thickness, stationary bed Subjects: Drilling Operations, Directional drilling This content is only available via PDF. 2003. SPE/IADC Drilling Conference You can access this article if you purchase or spend a download.