Abstract
ABSTRACTDue to the specificity of coal rock containing CBM (coal bed methane), large-sized cuttings from coal bed drilling present abnormal appearances which make the transport of cuttings more troublesome. Simulations of the transport of large-sized and non-spherical drilling cuttings in the horizontal well-bore annulus possesses both theoretical challenges and engineering worth. In this work, a coupled CFD-DEM model is developed and a multi-sphere method is adopted to construct the non-spherical cuttings particles including cubic and long flaky particles. Validation with the experimental data reveals the well applicability of the developed CFD-DEM model. The movements as well as the sedimentations of cuttings are discussed in detail. The influences of fluid velocity and particle shapes on the transport efficiency of cuttings are studied and more attention is paid to flaky cuttings. The results show that, with a consistent equivalent volume, relatively good performance happens to the 20 mm spherical particles while local piled bed appears to the flaky particles; however, cuttings in cubic particles behave the worst. In the chosen conditions, transport efficiency drops dramatically when the volume fraction of the flaky cuttings exceeds 10%. Work in this paper is expected to be able to be applied to CBM drilling engineering.
Highlights
Because of the specificity of the coal stratum and the structural complexity of the coal bed methane (CBM) wells, non-spherical cuttings in a larger size are more often produced during the drilling process
The validation cases indicate that the coupled CFDDEM is competent for the simulation of the transport of velocity inlet BCs: uniform bulk velocity; uniform particle-fluid volume fraction sectional grids cuttings and, the flaky particles are more appropriate to take the place of cuttings in the numerical simulations
Cuttings transport is studied for large non-spherical particles, which means cubic particles, spherical particles, and flaky particles in this work
Summary
Because of the specificity of the coal stratum and the structural complexity of the coal bed methane (CBM) wells, non-spherical cuttings in a larger size are more often produced during the drilling process. These large drill cuttings will bring impact failures to both strings and the well-wall, and generate local blockages which may cause serious downhole problems like the jamming of the drilling tools (Akbarian et al, 2018; Akhshik & Rajabi, 2018; Duan, Miska, Yu, Takach, & Ahmed, 2007). Where V denotes the volume of the fluid cell; Ff ,i denotes the force on the fluid cell and n denotes the particle quantity in the fluid cell
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Engineering Applications of Computational Fluid Mechanics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
