API RP 13M:2004 pdf download

API RP 13M:2004 pdf download.Recommended Practice for the Measurement of Viscous Properties of Completion Fluids.
8.3 Viscoelastic fluids
8.3.1 Introduction
For proper rheological characterization of this type of fluid, the fluid shall wet the walls of the measuring chamber and remain within the annular gap.
8.3.2 Apparatus
The properties of viscoelastic fluids shall be measured in a pressurized viscometer with a relatively wide gap.
Pressurization of the viscometer minimizes the effect of entrained air and reduces the Weissenberg effect
(bob climb). Multiple-point measurements may be suitable for determining the rheological behaviour of fluids.
For proper viscometric and rheological characterization, the following criteria shall be met.
a) Flow regime in the annular gap is laminar.
b) Slippage of the fluid at the walls within the gap is negligible.
c) The fluid exhibits essentially time-independent behaviour during any given measurement.
8.3.2.1 Pressurized concentric-cylinder viscometer, having the dimensions shown in Figure 3.
8.3.2.1.1 Calibration
Measure the temperature of the fluid being tested according to the manufacturer’s specified calibration procedure which shall be traceable to a national/international standard such as ISO, ASTM, DIN or equivalent.
Measure the rotor speed according to the manufacturer’s specified tachometer calibration procedure which shall be traceable to a national/international standard such as ISO, ASTM, DIN or equivalent.
Use one of the following calibration methods:
a) preferred method;
Verify system using a standardized Newtonian calibration fluid traceable to a national/international standard such as ISO, ASTM, DIN or equivalent. A calibration oil viscosity shall be selected to encompass the shear rate/shear stress envelope to be evaluated.
b) alternative torque-only calibration.
Measure according to the manufacturer’s specified calibration procedure (e.g. hanging weight), which shall be traceable to an international/national standard such as ISO, ASTM, DIN or equivalent.
8.3.2.1.2 Operation
8.3.2.1.2.1 Instrument preparation
Pre-heat thermal bath (if equipped) to test temperature. All temperatures in this document refer to actual
temperature of the fluid.
8.3.2.1.2.2 Procedure
The following procedures shall be followed.
a) Loading, pressurizing and heating the fluid
Load the fluid to be evaluated into the viscometer immediately after the last component is added according to the mixing procedure. Place 52 cm3 of fluid into the viscometer. This volume is sufficient to fully cover the bob. Pressurize the system with nitrogen to a minimum of 2,76 MPa (400 psi) and immediately start shearing at 100 s1. When shearing of the fluid starts, the elapsed time is defined as zero (,= 0) and heating of the fluid is begun. All actions in this paragraph shall be completed within 45 s.
Optional: ambient temperature shear ramp [described in 8.3.2.1.2.2 b)]. elapsed time is defined as zero (t = 0) immediately after completing this ramp, and fluid heating is begun.
At 20 mm elapsed time, higher than 3 °C (+ 5 °F) the remainder of the test,
the fluid temperature shall be no lower than 5 % below (base = 0 °C) and no above the desired test temperature. In addition, at 30 mm elapsed time, and for the fluid temperature shall be within ± 3 °C (± 5 °F) of the test temperature.
b) Application of shear rate ramps
The fluid shall be sheared at a constant 100 s initially and between shear rate ramps.
The time reported for each shear rate ramp is the elapsed t = 20 mm, shear rate ramps shall begin every 15 mm up to i = continuing up to 4 h 5 mm, ramps shall begin every 30 mm. ramps begin is at the discretion of the operator, however these
time before the ramp begins. Starting at 2 h 5 mm. Beginning at t = 2 h 35 mm and After 4 h 5 mm, the elapsed time before shall be reported.
The specified shear rates for all shear rate ramp are 25 s1, 50 s, 75 s1 and 100 s1. The shear rates during a ramp shall occur in the specified sequence, however the sequence of rates may be either montonically increasing or decreasing. Following each change in shear rate, the fluid shall be allowed to equilibrate for 25 s. This is followed by 5 s of data collection. Each new shear rate shall be attained within the first 5 s after completing data collection at the previous shear rate. When a sequence of increasing shear rates is used, a 40-s equilibration period shall be allowed before collecting data at a shear rate of 25 s. Then proceed as described above. Table I shows the viscometer speed, in revolutions per minute, corresponding to each shear rate based on the specified viscometer geometry.
c) Data reporting
For each shear rate during a shear rate ramp, record viscosity data at least once per second and report the arithmetic average of the data obtained. At all other times, report viscosity data at least once per minute.
8.3.2.1.3
Calculations
Viscometric calculations shall be made according to the manufacturer’s recommended calculaflon procedure.
For rheological calculations, see Clause 9.