**3.4. Mud filtration properties**

56 New Technologies in the Oil and Gas Industry

1. The aged mud samples were agitated for 2 minutes using the Hamilton Beach Mixer. 2. The clean, dry mud balance cup was filled to the top with the newly agitated mud. 3. The lid was placed on the cup and the balance was washed and wiped clean of

4. The balance was placed on a knife edge and the rider moved along the arm until the

5. The mud weight was read at the edge of the rider towards the mud cup as indicated by

7. The mud was poured into the mud cup of the rotary viscometer shown in Diagram 4, and the rotor sleeve was immersed exactly to the fill line on the sleeve by raising the

9. The speed selector knob was first rotated to the stir setting, to stir the mud for a few seconds, and it was rotated at 600RPM, waiting for the dial to reach a steady reading,

10. The above process was repeated for 300 RPM, 200 RPM, 100 RPM, 60 RPM, 30 RPM and

12. The speed selector knob was then rotated to to stir the mud sample for a few seconds,

then it was rotated to gel setting and the power was immediately shut off.

8. The power switch located on the back panel of the viscometer was turned on.

overflowing mud while covering the hole in the lid.

the arrow on the rider and was recorded. 6. Steps 2 to 5 were repeated for the other samples.

the 600 RPM reading was recorded.

11. Steps 7 to 10 were repeated for other samples.

cup and arm were balanced as indicated by the bubble.

platform. The lock knot on the platform was tightened.

**3.1. Density** 

**3.2. Viscosity** 

6 RPM.

**Figure 4.** Rotational Viscometer

**3.3. Gel strength** 


**Figure 5.** API Filter Press


#### **3.5. Hydrogen ion concentration (pH)- Colorimetric paper method**


### **4. Toxicity test**

29. After the oil based mud samples have been formulated, each is then tested on a growing plant (that is on beans seedling), to see the effects on the plant growth and the living organisms in the soil. Bean seed was planted and exposed to 100ml of three different mud samples, with the following base fluids; diesel, canola and jatropha, the growth rate was measured, and the number of days of survival.

#### **4.1. Results of density measurements**

The results as obtained from measurements of density using the mud balance are contained in Table 2 below.


**Table 2.** Mud density values

Mud density ρ is calculated using eqn *Ben Oil Water m Ben Oil Water M MM V VV*  e.g for Jatropha

58 New Technologies in the Oil and Gas Industry

valve was carefully opened.

side of the dispenser.

recorded.

**4. Toxicity test** 

in Table 2 below.

22. At the end of 30 minutes the volume of filtrate collected was measured. The air flow through the pressure regulator was shut off by turning the T-screw in a counterclockwise direction. The valve on the pressure source was then closed and the relief

24. The filter cake was measured using a vernier caliper, and the measurements were

27. After the color of the test paper stabilized, the color of the upper side of the paper, which had not contacted the mud, was matched against the standard color chart on the

29. After the oil based mud samples have been formulated, each is then tested on a growing plant (that is on beans seedling), to see the effects on the plant growth and the living organisms in the soil. Bean seed was planted and exposed to 100ml of three different mud samples, with the following base fluids; diesel, canola and jatropha, the

The results as obtained from measurements of density using the mud balance are contained

**Diesel** 8.26 8.261 0.01 119.1 **Algae** 7.81 7.815 0.005 126.5 **Jatropha** 8.32 8.326 0.06 154.5 **Moringa** 8.30 8.307 0.007 149.3 **Canola** 8.47 8.470 0 150.6

*m*

**CALCULATED DENSITY (ppg)** 

*Ben Oil Water*

*M MM V VV*

**ERROR Barite (g)** 

23. The assembly was then dismantled, and the mud was removed from the cup.

25. The above procedures were carried out for the other mud samples.

26. A short strip of pH paper was placed on the surface of the sample.

growth rate was measured, and the number of days of survival.

28. Steps 26 and 27 were carried out on other samples.

**4.1. Results of density measurements** 

**SAMPLE MEASURED** 

**Table 2.** Mud density values

**DENSITY (ppg)** 

Mud density ρ is calculated using eqn *Ben Oil Water*

**3.5. Hydrogen ion concentration (pH)- Colorimetric paper method** 

$$\rho\_{m,l} = \frac{0.110231 + 0.38040768 + 0.76742464}{0.0924608 + 0.0528344 + 0.005079769585} = 8.326 \text{ ppg}$$

From the above table, the error differences between the calculated and measured densities all lie below 0.1, thus the readings obtained using the mud balance have a high accuracy. It also showed that the denser the base oil, the higher the amount of barite needed to build.

### **4.2. Viscosity and gel strength results**

Viscosity readings obtained from the experiment carried out on the rotary viscometer are contained in Table 3.

The dial reading values (in lb/100ft2) are tabulated against the viscometer speeds in RPM.

Viscosity values are calculated with equations

Apparent viscosity= Dial Reading at 600RPM (θ600)/2


**Table 3.** Viscometer Readings for Diesel, Jatropha and Canola OBM's


**Table 4.** Plastic Viscosities, Apparent Viscosities, Gel Strength,

Diesel OBM had the highest apparent viscosity, followed by Moringa, then Jatropha, Canola and algae OBM's

**Figure 6.** Viscometer Plot for Diesel OBM

**Figure 7.** Viscometer Plot for Jatropha OBM

**Figure 8.** Viscometer Plot for Moringa OBM

**Figure 9.** Viscometer Plot for algae OBM

**Figure 6.** Viscometer Plot for Diesel OBM

**Figure 7.** Viscometer Plot for Jatropha OBM

**Figure 8.** Viscometer Plot for Moringa OBM

**Figure 10.** Viscometer Plot for Canola OBM

**Figure 11.** Combined viscometer plot for Diesel, Algae, and jatropha OBM's

It can be seen that the plots on Figures 6 to 11, generated from the dial readings of all the mud samples are similar to the Bingham plastic model. This goes to prove that the muds have similar rheological behaviour.

However, not all the lines of the plot are as straight as the Bingham plastic model. This can be explained by a number of factors such as: possible presence of contaminants, and the possibility of behaving like a different model such as Herschel Bulkley.

A Bingham plastic fluid will not flow until the shear stress τ exceeds a certain minimum value τy known as the yield point9 (Bourgoyne et al 1991). After the yield has been exceeded, the changes in shear stress are proportional to changes in shear rate and the constant of proportionality is known as the plastic viscosity µp.

From Figures, the yield points of the different muds can be read off. The respective yield points are the intercepts on the vertical (shear stress) axes.

For reduced friction during drilling, algae OBM gives the best results, followed by Jatropha OBM then moringa OBM.

This means Diesel OBM offers the greatest resistance to fluid flow. Algae, Jatropha, Moringa and Canola OBM's pose better prospects in the sense that their lower viscosities will mean less resistance to fluid flow. This will in turn lead to reduced wear in the drill string10.

#### **4.3. Mud filtration results**

The filtration tests were carried out at 350 kPa due to the low level of the gas in the cylinder.

The mud cakes obtained from the API filter press exhibited a slick, soft texture.

From Table 5 and Figures 12 to 15, we can infer that Diesel OBM had the highest rate of filtration and spurt loss. Comparing this to a drilling scenario, this means that the mud cake from Diesel OBM is the most porous, and the thickest.

From these inferences, we can see that Algae, Jatropha, Moringa and Canola OBM's are better in filtration properties than Diesel OBM as inferred from thickness and filtration volumes.

**Figure 12.** Filtration Volumes for Diesel, Algae, Jatropha and Moringa OBM's

**Figure 13.** Filtration Volumes for Diesel, Jatropha and Canola OBM's

OBM then moringa OBM.

**4.3. Mud filtration results** 

However, not all the lines of the plot are as straight as the Bingham plastic model. This can be explained by a number of factors such as: possible presence of contaminants, and the

A Bingham plastic fluid will not flow until the shear stress τ exceeds a certain minimum value τy known as the yield point9 (Bourgoyne et al 1991). After the yield has been exceeded, the changes in shear stress are proportional to changes in shear rate and the constant of

From Figures, the yield points of the different muds can be read off. The respective yield

For reduced friction during drilling, algae OBM gives the best results, followed by Jatropha

This means Diesel OBM offers the greatest resistance to fluid flow. Algae, Jatropha, Moringa and Canola OBM's pose better prospects in the sense that their lower viscosities will mean

The filtration tests were carried out at 350 kPa due to the low level of the gas in the cylinder.

From Table 5 and Figures 12 to 15, we can infer that Diesel OBM had the highest rate of filtration and spurt loss. Comparing this to a drilling scenario, this means that the mud cake

From these inferences, we can see that Algae, Jatropha, Moringa and Canola OBM's are better in filtration properties than Diesel OBM as inferred from thickness and filtration volumes.

less resistance to fluid flow. This will in turn lead to reduced wear in the drill string10.

The mud cakes obtained from the API filter press exhibited a slick, soft texture.

**Figure 12.** Filtration Volumes for Diesel, Algae, Jatropha and Moringa OBM's

possibility of behaving like a different model such as Herschel Bulkley.

proportionality is known as the plastic viscosity µp.

points are the intercepts on the vertical (shear stress) axes.

from Diesel OBM is the most porous, and the thickest.

**Figure 14.** Mud Cake Thicknesses for Diesel, Algae, Canola OBM's

**Figure 15.** Mud Cake Thicknesses for Diesel, Jatropha and Canola OBM's


**Table 5.** Mud Filtration Results

Problems caused as a result of excessive thickness include4:


The problems as a result of excessive filtration volumes include4:

