Modeling of Transient Cuttings Transport in Underbalanced Drilling (UBD)

Abstract

Underbalanced drilling (UBD) holds several important advantages over conventional drilling technology. These include minimization of formation damage, faster penetration rate, and ability for evaluation of reservoir productivity during the drilling process. As UBD technology matures, it has also been used more and more in different applications. However, many aspects of UBD technology remain poorly understood. The model presented in this paper seeks to understand the mechanisms involved in the transport of cuttings in UBD.The model simulates the transport of drill cuttings in an annulus of arbitrary eccentricity and includes a wide range of transport phenomena, including cuttings deposition and resuspension, formation, and movement of cuttings bed. The model consists of conservation equations for the fluid and cuttings components in the suspension and the cuttings deposit bed. Interaction between the suspension and the cuttings deposit bed, and between the fluid and cuttings components in the suspension, are incorporated. Solution of the model determines the distribution of fluid and cuttings concentration, velocity, fluid pressure, and velocity profile of cuttings deposit bed at different times.The model is used to determine the critical transport velocity for different hydrodynamic conditions. Results from the model agree quite closely, qualitatively, with experimental data obtained from a cuttings transport flow loop at the Technology Research Center of the Japan Natl. Oil Corp. (TRC/JNOC)'s Kashiwazaki Test Field in Japan. These results show the importance of slippage in the formation of the cuttings deposit bed. The model is useful in evaluating the minimum flow rate for effective cuttings removal in UBD.

Review of Hole Cleaning in Complex Structural Wells

“…As shown in Table 2 and Table 3, even more factors such as mud rheology, cuttings concentration were considered in some correlations and models, complexity of cuttings transport leads to the big gap between theoretic studies and real drilling conditions. Therefore, steady layer models [51,55], transient models [32,[56][57][58][59][60], multi-region models [61,62], correlations [25,37,38,63] constantly appeared in the recent years.…”

“…The transient model proposed by Doan et al [60] can simulate the cuttings transport of an annulus of arbitrary eccentricity and include cuttings deposition and resuspension, formation, and movement of cuttings bed. The interaction between fluid phase and solid phase in suspended layer, and interaction between cuttings bed and suspended layer were incorporated.…”

Numerical Modelling of Cuttings Transport with Foam in Inclined Wells

“…This approach has been originally used for modeling of slurry transport in pipes [68][69][70]. Several studies in petroleum drilling engineering on cuttings transport modeling have also used the twolayer modeling approach [54][55][56][57][58][59][60][61][62].…”

“…Leighton and Acrivos [109] also investigated the resuspension process and explain it in terms of shear-induced diffusion process, in which the diffusivity resulted from inter-particle interaction within a suspension as it is sheared. Doan et al [62] assumed that deposition and entrainment rates determine the volumetric transfer rate across the interfacial boundary aligned in the direction perpendicular to bulk flow. The depositional rate was expressed as a function of hindered terminal velocity of a single particle.…”

Flow Patterns and Minimum Suspension Velocity for Efficient Cuttings Transport in Horizontal and Deviated Wells in Coiled-Tubing Drilling

“…Kamp and Rivero 13 provided numerical simulations for eccentric annuli, while Li and Walker 5 derived the significant parameters affecting cuttings transport through sensitivity analysis of the twolayer model. Doan et al 32 extended the two-layer model to three phases to cover underbalanced-drilling situations. All these approaches covered the flow patterns described previously and resulted in a system of four algebraic equations and one integral equation describing the turbulent diffusion of solids.…”