Cuttings-Transport Simulation Combined With Large-Scale-Flow-Loop Experimental Results and Logging-While-Drilling Data for Hole-Cleaning Evaluation in Directional Drilling

Abstract

Summary The authors have developed a 1D two-layer-model transient-cuttings-transport simulator that predicts the transient behaviors of cuttings transport, including the concentration and slip velocity of suspended cuttings, bed height of cuttings, annular pressure, and equivalent circulating density (ECD) along the entire trajectory of a complex extended-reach well. Model parameters, such as annulus-friction factor, cuttings-deposition rate, and re-entrainment rate, were determined from numerous experiments previously performed by use of a large-scale cuttings-transport flow-loop apparatus. This apparatus simulates the complex flows in borehole annuli at various inclination angles, ranging from vertical to horizontal. In this study, the authors validate the model and analyze the cuttings transport by use of field data in a directional well, in which the annular ECD was measured by logging while drilling (LWD), and the rate of the returned cuttings was measured at the surface. On the basis of the simulation study, the potential of the developed transient-cuttings-transport simulator for the predrilling- and post-drilling-phase analyses is discussed. Moreover, the authors evaluate the transient-hole-cleaning conditions and the ECD behavior from the LWD data.