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Surface chemistry and rheological properties of API bentonite drilling fluid: pH effect, yield stress, zeta potential and ageing behaviour
- Source :
- Journal of Petroleum Science and Engineering. 146:561-569
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- API bentonite, a key ingredient of drilling muds, displayed a negative zeta potential across the whole pH range of 2.5–12.3. It contained two very rheological active ingredients, sodium montmorillonite or Na+Mt (40.4%) and needle-shape sepiolite (16%). Due to the interplay of these two ingredients, the rheological behaviour displayed by the API bentonite suspensions is quite different to other bentonite suspensions. The gel displayed a very low or no yield stress at low acidic pH and a maximum yield stress at pH 8–12. Magnesium leaching from sepiolite at low pH and its hydrolysis plays a role in affecting the rheological properties at high pH. Yield stress and ageing behaviour was observed in suspensions with at least 3 wt% solids. The Herschel-Bulkley (HB) model described the flow behaviour of these gels. Both the HB yield stress and viscosity at a fixed shear rate of the 7 wt% gel peaked at pH 8.5 and were smallest at pH 5.2. The ageing or structural recovery behaviour is most pronounced at high pH for the most concentrated gels. Both the Leong and Nguyen-Boger ageing models described the structural recovery behaviour well. The recovery of the recently discovered very open honeycomb structure formed by Na+MT gel, after breakdown by shear was invoked to explain the ageing behaviour.
- Subjects :
- Thixotropy
Chemistry
Sepiolite
Mineralogy
020101 civil engineering
02 engineering and technology
021001 nanoscience & nanotechnology
Geotechnical Engineering and Engineering Geology
0201 civil engineering
Shear rate
Viscosity
chemistry.chemical_compound
Fuel Technology
Montmorillonite
Chemical engineering
Rheology
Bentonite
Zeta potential
0210 nano-technology
Subjects
Details
- ISSN :
- 09204105
- Volume :
- 146
- Database :
- OpenAIRE
- Journal :
- Journal of Petroleum Science and Engineering
- Accession number :
- edsair.doi...........c5c3134323f95accab9e4ab40714ab21
- Full Text :
- https://doi.org/10.1016/j.petrol.2016.07.016