Chapter 5
asphaltene content is more oil-wet. At the same layer, sample with N/В ratio 0.7
has higher asphaltene content in solid than that with N/В ratio 4.0.
Table 5.7 Asphaltene content of solid in different layers of emulsion
|
Emulsion sample |
Asphaltene % of solid | ||
|
Oil layer |
Rag layer |
Bottom of water layer | |
|
N∕B 4.0 and 200 ppm 6057 |
32 |
20 |
14 |
|
N∕B 4.0, 200 ppm 6057 and |
29 |
20 |
15 |
|
N∕B 0.7 and 200 ppm 6057 |
37 |
28 |
20 |
5.10. Remarks on emulsion separation
Based on bottle test, with demulsifier, almost complete separation of oil and
water could be achieved without solids in emulsion, and no rag layer formed. This
reveals that solid in bitumen froth has key effect on emulsion stability.
Comparison of separation results show that emulsion with dilution ratio 4.0 is
less stable than that with dilution ratio 0.7. In emulsion sample with dilution ratio
4.0, residual water and solid in oil are lower and the rag layer is almost eliminated.
The reason could be the viscosity and density difference of diluted bitumen with
N∕B 0.7 and 4.0. Based on Stokes’ Law, sedimentation rate of water in diluted
bitumen with N/В ratio 4.0 is 8.1 times faster than that with N/В ratio 0.7. It is
recommended to break the rag layer in emulsion at dilution ratio 4.0.
185