ADVANCES IN THEORETICAL RESEARCH ON ANNULAR HYDRAULICS AND CUTTINGS TRANSPORT

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ADVANCES IN THEOKETICAL RESEAKCH ON ANNULAR HYDRAULICS AND CUTTINGS TRANSPORT

The paper gave an overviews about the achievements gained in the annular hydraulics study in the Universityof Petroleum in resent ten years,particularly in the domains of(1) Analysis of properties of axial laminar flow field of Power-Law and Newtonian fluids in the concentric annuli of a vertical well.The development of models for velocity,apparent viscosity,flow rate and pressure loss and so forth.(2)Analysis of the helical laminar flow field of a purely-viscous fluid flowing through a concentric annuli of a vertical well.(3)The study on flow proper-tics of Power-Law fluid and axial laminar flow field of Bingham fluid in an eccentric annulus of a directional well.(4)The study on cuttings transport mechanism and rules in the annulus sapace of the inclined and horizontal wells.Four flow patterns of cuttings transport were observed on test unit. After analysizing the factors affecting cuttings movement,a the oretical model for the cuttings-bed thickness was developed along the lines of the two-layer in highly-deviated well.On the basis of numerous tests in the laboratory,the empirical models for the cuttings-bed height were developed in the hightly angle and horizontal wellbores. All the results mentioned above , have verified in the oil field pratics, and have been successfully applied to the directional well drilling.