Effect of casing surface roughness on the removal efficiency of non-aqueous drilling fluids

Zhidong Zhang, George W. Scherer, Robert K. Prod'Homme, Myoungsung Choi

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


The primary function of natural gas well cementing is to provide downhole zonal isolation. However, the residual non-aqueous drilling fluid in cement and on the surface of the casing can weaken the bond of hardened cement to the casing. In this paper, the amount of remaining drilling fluid both in cement and on the casing is quantified by the fluorescent dye method, which is verified by other two methods, mass difference and laser scanning. The essential factor - surface roughness that can significantly affect the amount of residual drilling fluid - is investigated. Results show good correlations between the thickness of the remaining drilling fluid and the surface roughness. The comparison of mud removal efficiency of two commercial spacers indicates that microemulsion can remove more drilling fluid than the common spacer, as pointed out in the literature; however, microemulsion is also apt to remain on the casing and thus reduce the bonding between cement and the casing.

Original languageEnglish (US)
Pages (from-to)155-165
Number of pages11
JournalJournal of Natural Gas Science and Engineering
StatePublished - Mar 1 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Energy Engineering and Power Technology
  • Geotechnical Engineering and Engineering Geology
  • Fuel Technology


  • Cement spacer
  • Fluorescent dye
  • Oil field cementing
  • Removal efficiency
  • Residual mud thickness
  • Wettability


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