Determination of the rheological parameters of the drilling fluid

Operating procedure for drilling fluid performance test


Operating Procedure for Drilling Fluid Performance Test

Determination of the Rheological Parameters of the Drilling Fluid

The rheological parameters of drilling fluid include apparent viscosity, plastic viscosity, dynamic shear stress (yield value), initial cutting, final cutting, flow index (the strength of non-Newtonian properties of reaction drilling fluid, general drilling fluid n value is less than 1, the smaller n, the stronger non-Newtonian, the greater the denaturation, the n range of drilling fluid is between 0.70~0.45), consistency coefficient (thinning degree of reaction drilling fluid), water eye viscosity (extreme high shear viscosity), Carson shear force, etc. The above parameters can be determined by a Fan's six-speed rotational vistometer.

ZNN-D6 six-speed rotational viscometer: drilling fluid in the annular space between two concentric cylinder, through the variable speed drive outer cylinder at constant speed, the outer cylinder through the measured liquid on the inner cylinder, with the torsion spring connecting the inner cylinder rotate a corresponding Angle, according to Newton's law, the size of the corner is proportional to the viscosity of the liquid, so the measurement of the liquid viscosity to the inner cylinder corner. The needle reading reflected in the dial is calculated as the drilling fluid viscosity and shear force. The measuring part is composed of torsion spring assembly, dial assembly, inner and outer cylinder, the support part adopts bracket lifting, without stop can be changed,

Specification: Viscosity measurement range: to Newtonian fluid 0~300mPa.s

                                                                        to the non-Newtonian fluid, 0~150mPa.s

1. Check and Check Before Startup

1. Turn on the power, the indicator light on, check the instrument for leakage.

2. Check that the instrument is level.

3. Gently turn the inner cylinder of 5 small boxes by hand to check whether the instrument rotation is sensitive. Turn a small case to swing back and forth more than 5 times is sensitive, do not swing the instrument can not be used, need to check and repair.

4. Turn the instrument with 3 r/min or 6 r/min for 3min in summer and 5min in winter, and check whether the instrument is running and the speed is constant.

5. Use 600 r/min to check whether the instrument swings. When the outer cylinder swings obviously, change the direction of the outer cylinder bayonet and tighten the outer cylinder

6. Turn at 300 r/min to check whether the zero position of the dial pointer swings. If the pointer is not at the zero position, it should be checked according to the instrument manual.

2. Determine

1. After the instrument check, filter the tested drilling fluid with the funnel viscosity gauge screen, and then heat it to the required temperature, and stir for more than 10min. For well site measurement, the sampling time shall be minimized (if possible) and the drilling fluid temperature shall be as close as possible to the drilling fluid temperature (the temperature difference shall not exceed 6℃). The sampling location should be indicated on the report form.

2. Inject the sample into the sample cup to the dial line (350 mL) and place it on the tray with the rising level within the cup to the dial line.

3. Measure and record the temperature of the drilling fluid.

4. After rotating the drum at 600 r/min until the reading value on the dial is constant (the required time depends on the performance of the drilling fluid), read and record the dial reading at 600 r/min. Record the readings on the dial, at 300 r/min, 200 r/min, 100 r/min, 6 r/min and 3 r/min in the same method.

5. The drilling fluid sample was stirred at 600 r/min for 10s bell. After stopping the stirring, set the drilling fluid sample to stand for 10s bell, determine the maximum reading after 3 r/min speed starting rotation, and calculate the initial shear force (10s shear force) in Pa.

6. The drilling fluid sample was stirred at 600 r/min for 10s, then let for 10min. The maximum reading after 3 r/min speed started rotation, and the final shear force (10min shear force) was calculated in Pa.

7. After testing, turn off the power supply, release the tray, and remove the sample cup.

8. Gently rotate the left cylinder to remove the outer cylinder, rotate counterclockwise and vertically downward force to remove the inner cylinder (generally do not remove the inner cylinder, directly clean with water brush).

9. Clean the instrument and dry, good on the inner and outer tube.


Primary cut (G10 s) =0.5 Φ 3 (Pa)

Final cut (G10 min) =0.5 Φ 3 (Pa)

Apparent viscosity (AV) =1 / 2 (Φ 600) (mPa.s)

Plasmotic viscosity (PV) = Φ 600- Φ 300 (mPa.s)

Dynamic tangent stress (YP) = (Φ 300-PV) / 2 (Pa)

Pseudplastic fluid: Fluidity index (n) = 3.322 lg (Φ 600 / Φ 300)

Consistency coefficient (K) =0.511 [Φ 300 / (511) n] (

Viscosity of water eyes (η) = {1.20 (Φ 6001 / 2- Φ 1001 / 2)} 2 (mPa.s)

Carson dynamic shear force (τ c) = {15.6 (Φ 1001 / 2- Φ 6001 / 2)} 210-3 (Pa)

4. matters need attention

1. During the measurement, the engraved line of the rotating cylinder must be just flooded by the measured drilling fluid. The shear force determination is the maximum value at 3 r/min of rotation.

2. The injected sample amount and the immersion depth of the head must be strictly controlled, otherwise the measurement results will be wrong due to the "boundary effect" of the head.

3. When unloading the inner and outer cylinder, it should be gently unloaded, and avoid collision or excessive force. Clean the inner tube and block the cone hole with your fingers to avoid getting the stolen goods and liquid into the cavity.

4. Because the spacing between the inner and outer cylinders is very small, large solid phase particles and large bubbles will interfere with the determination, and the existence of a large number of small bubbles will distort the determination results. Therefore, defoaming should be carried out before determination, and can be added if necessary.

5. The measurement must be carried out successively from high speed to low speed, and can not be reversed. For most drilling fluids, especially the drilling fluids with large touch degeneration, the results measured in different orders are not repeated.

Qingdao Haitongda Special Instrument Co.,Ltd.

Qingdao Haitongyuanda Special Instrument Co.,Ltd.



Registered Address



No.320, Jiushui East Road,Licang district

Qingdao City,Shandong Province,China

Postal Address

No.10Huaan Road,Chengyang district

Qingdao City,Shandong Province,China