Impact of additives with opposing effects on the rheological properties of bentonite drilling mud: Flow, ageing, microstructure and preparation method

Mingyong Du, Pengfei Liu, Peta L. Clode, Jishan Liu, Bashirul Haq, Yee Kwong Leong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Drilling fluids are formulated with a range of additives to achieve the desired functional properties including specific rheological properties. Its rheology, a critical property, is sensitive to the chemicals used in its formulation and the environment encountered during drilling. The flow and time-dependent behaviour of bentonite slurries were evaluated under the influence of KCl and P2O74− or MgCl2 and P3O105− at specific concentrations. The multi-charge phosphate anions weakened the gel and its ageing behaviour at low KCl or MgCl2 content. At high KCl concentration, the sequence of salt addition in the gel preparation has a significant effect on the gel strength and stability. The gel was very strong when the platelets were allowed to exfoliate before the salt addition. When the delamination was hindered, a weak and at time an unstable gel was produced as a result of low platelet concentration. The gels prepared by both methods displayed time-independent behaviour at high KCl concentration. The ageing behaviour was described well by the Leong model. The cryo-SEM images revealed different microstructures and particle interaction configurations between gels with low and high salt concentration containing 0.5 dwb% P2O74−. The phosphate-based additives adsorbed at the platelet edge and weakened the platelet-platelet attraction at the network junctions. The opposing effect of Mg2+ at 0.01M to the effect of 0.5 dwb% dwb% P3O105− on the rheological properties of the bentonite gel is weak.

Original languageEnglish
Article number107282
JournalJournal of Petroleum Science and Engineering
Volume192
DOIs
StatePublished - Sep 2020

Bibliographical note

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

  • Bentonite drilling fluid
  • Ground water chemicals
  • Preparation method
  • Rheology
  • Shale stability

ASJC Scopus subject areas

  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology

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