Abstract. Hole cleaning is one of the key techniques of extended reach drilling. Compared with horizontal and vertical well section, the cuttings transport in inclined section is more complicated and difficult to be solved analytically, especially affected by drill pipe rotation. Computational fluid dynamics method is used to simulate the cuttings-mud two-phase flow in the annulus of inclined section. Simulation result shows that back flow is a remarkable feature of cuttings transport in inclined well section. Drill pipe rotation turns the axial motion of cuttings in annular into the helical motion. Drill pipe rotation can not only reduce the total cuttings concentration in annular, but also increase the average cuttings velocity. Section with 40～60 degree of deviation angle is the most difficult cleaned section, where cuttings concentration and pressure drop are also bigger than the rest sections.

A method was developed for the determination of 19 perfluoroalkyl acids (PFAs) in lamb liver by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) combined with dispersive solid phase extraction. The sample was extracted with acidified acetonitrile, and then cleaned-up by a mixture of N-propylethylenediamine (PSA), C18 and graphitized carbon black (GCB) sorbents. The 19 PFAs were analyzed by HPLC-MS/MS with a C18 chromatographic column, adopting the multiple reaction monitoring (MRM) mode with negative electrospray ionization. The effects of the dosages of hydrochloric acid and the sorbents on the recoveries of the 19 PFAs were studied. For accurate quantitative analysis, the isotope internal standard method was used. The calibration curves were linear with the correlation coefficients over 0.998 in the range of 0.05-20 µg/kg for the 19 PFAs. The limits of detection were 0.004-0.111 µg/kg. The limits of quantification were 0.012-0.370 µg/kg. The mean recoveries of the 19 PFAs at spiked levels of 0.5, 1.0, 2.0 µg/kg were in the range from 80% to 128% with the relative standard deviations of 0.31%-11.1%. The developed method is rapid, simple, accurate. It is suitable for the determination of the 19 PFAs in large quantities of lamb liver samples.

No abstract