Old Lesson 17B 1 1 Well Drilling Engineering Pressure Drop Calculations API Recommended Practice 13D Dr DO QUANG KHANH 2 Contents The API Power Law Model The Rotational Viscometer A detailed Exampl[.]
Well Drilling Engineering Pressure Drop Calculations API Recommended Practice 13D Dr DO QUANG KHANH 1 Contents The API Power Law Model The Rotational Viscometer A detailed Example - Pump Pressure Pressure Drop in the Drillpipe Pressure Drop in the Bit Nozzles Pressure Drop in the Annulus Wellbore Pressure Profiles Power Law Model K = consistency index n = flow behaviour index τ=K γn Linear Plot SHEAR STRESS τ psi SHEAR RATE, γ , sec-1 Fluid Flow in Pipes and Annuli LOG (PRESSURE) (psi) LOG (VELOCITY) (or FLOW RATE) Fluid Flow in Pipes and Annuli Laminar Flow Turbulent LOG (SHEAR STRESS) (psi) LOG ( SHEAR RATE ), n ( RPM or sec −1 ) Rotating Sleeve Viscometer Rotating Sleeve Viscometer (RPM * 1.703) VISCOMETER RPM SHEAR RATE 100 ANNULUS 5.11 170.3 300 600 DRILL STRING 511 1022 sec -1 BOB SLEEVE API RP 13D API RP 13D, June 1995 for Oil-Well Drilling Fluids API RP 13D recommends using only FOUR of the six usual viscometer readings: Use 3, 100, 300, 600 RPM Readings The and 100 RPM reading are used for pressure drop calculations in the annulus, where shear rates are, generally, not very high The 300 and 600 RPM reading are used for pressure drop calculations inside drillpipe, where shear rates are, generally, quite high Example: Pressure Drop Calculations Example Calculate the pump pressure in the wellbore shown on the next page, using the API method The relevant rotational viscometer readings are as follows: R3 = (at RPM) R100 = 20 (at 100 RPM) R300 = 39 R600 = 65 (at 300 RPM) (at 600 RPM) Pressure Drop Calculations PPUMP Q = 280 gal/min ρ = 12.5 lb/gal PPUMP = ∆PDP + ∆PDC + ∆PBIT NOZZLES + ∆PDC/ANN + ∆PDP/ANN + ∆PHYD 10