2006 年 71 巻 6 号 p. 609-617
Cuttings transport behavior in drilling directional wells was experimentally investigated using a once-through type large-scale flow loop apparatus, the Cuttings Transport Flow Loop System (CTFLS) in the Japan Oil, Gas and Metals National Corporation Kashiwazaki Test Field. The annular test section of the CTFLS is 9-m long and consists of a 5" ID transparent casing pipe and a 2.063" OD drillpipe. The inclination of the test section can be set at an angle from 0 to 90° in 15° increments. Drillpipe can be mounted either in concentric or eccentric mode.
Experiments using two types of drilling mud, water and 0.15% PHPA solution, were conducted to focus on the effects of parameters such as hole inclination angle, drillpipe eccentricity, mud flow rate, mud rheology and rate of penetration (ROP). In the test procedure, mud was circulated and cuttings were fed into the test section both at constant rates, supposing a condition of drilling with constant ROP. Then, for predetermined mud flow rates, quantitative data in steady-state condition such as volumetric concentration of cuttings in the annulus, cuttings bed height and frictional pressure loss were measured. Critical flow rate determination based on a cuttings concentration criteria defined in this study was also presented, and optimum mud flow rate in actual field operation was discussed from a more practical point of view.