Crude oil–brine–rock interactions in tight chalk reservoirs: An experimental study

Samira Mohammadkhani, Benaiah U. Anabaraonye, Armin Afrough, Rasoul Mokhtari, Karen Louise Feilberg

Research output: Contribution to journalArticleResearchpeer-review

5 Citations (Scopus)

Abstract

We present a systematic study of crude oil–brine–rock interactions in tight chalk cores at reservoir conditions. Flooding experiments are performed on outcrops (Stevns Klint) as well as on reservoir core plugs from Dan field, the Ekofisk and Tor formations. These studies are carried out in core plugs with reduced pore volumes, i.e., short core samples and aged with a dynamic ageing method. The method was evaluated by three different oil compositions. A series of synthetic multi-component brines and designed fluid injection scenarios are investigated; injection flow rates are optimized to ensure that a capillary-dominant regime is maintained. Changes in brine compositions and fluid distribution in the core plugs are characterized using ion chromatography and X-ray com-puted tomography, respectively. First, we show that polar components in the oil phase play a major role in wettability alteration during ageing; this controls the oil production behavior. We also show that, compared to seawater, both formation water and ten-times-diluted seawater are better candi-dates for enhanced oil recovery in the Dan field. Finally, we show that the modified flow zone indi-cator, a measure of rock quality, is likely the main variable responsible for the higher oil recoveries observed in Tor core samples.

Original languageEnglish
Article number5360
Number of pages19
JournalEnergies
Volume14
Issue number17
DOIs
Publication statusPublished - Sep 2021
Externally publishedYes

Keywords

  • Chalk
  • Core flooding
  • Crude oil–brine–rock interactions
  • Low salinity water
  • Short core plug

Programme Area

  • Programme Area 3: Energy Resources

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