Novel insights into mechanisms of oil recovery by low salinity water injection

Mehran Sedah Sohrabi, Pedram Mahzari, Seyed Amir Farzaneh, John Robert Mills, P. Tsolis, Shaun Ireland

Research output: Chapter in Book/Report/Conference proceedingConference contribution

29 Citations (Scopus)

Abstract

The underlying mechanism of oil recovery by low salinity water injection (LSWI) is still unknown. It would, therefore, be difficult to predict the performance of reservoirs under LSWI. A number of mechanisms have been proposed in the literature but these are controversial and have largely ignored crucial fluid/fluid interactions. Our direct flow visualization investigations have revealed that a physical phenomenon takes place when certain crude oils are contacted by low salinity water leading to a spontaneous formation of micelles which can be seen in the form of micro-dispersions in the oil phase. In this paper, we present the results of a comprehensive study that includes experiments at different scales designed to systematically investigate the role of the observed crude oil/brine interaction and micelle formation in the process of oil recovery by LSWI. The experiments include; direct flow (micromodel) visualization, crude oil characterization, coreflooding, and spontaneous imbibition experiments. We establish a clear link between the formation of these micelles, the natural surface active components of crude oil, and the improvement in oil recovery due to LSWI. We present the results of a series of spontaneous and forced imbibition experiments carefully designed using reservoir cores to investigate the role of the micro-dispersions in wettability alteration and oil recovery. To further assess the significance of this mechanism, in a separate exercise, we eliminate the effect of clay by performing a LSWI experiment in a clay-free core. Absence of clay minerals is expected to significantly reduce the influence of the previously proposed mechanisms for oil recovery by LSWI. Nevertheless, we observe significant additional oil recovery compared to high salinity water injection in the clay-free porous medium. The additional oil recovery is attributed to the formation of micelles stemming from the crude oil/brine interaction mechanism described in this work and our previous related publications. Compositional analyses of the oil produced during this coreflood experiment indicates that the natural surface active compounds of the crude oil had been desorbed from the rock surfaces during the LSWI period of the experiment when the additional oil was produced. The results of this study present new insights into the fundamental mechanisms involved in oil recovery by LSWI and new criteria for evaluating the potential of LSWI for application in oil reservoirs. The fluid/fluid interactions revealed in this research applies to oil recovery from both sandstone and carbonate oil reservoirs.

Original languageEnglish
Title of host publicationSPE Middle East Oil and Gas Show and Conference, MEOS, Proceedings
PublisherSociety of Petroleum Engineers
Pages2491-2508
Number of pages18
ISBN (Print)9781613993439
DOIs
Publication statusPublished - 2015
Event19th Middle East Oil and Gas Show and Conference 2015 - Manama, Bahrain
Duration: 8 Mar 201511 Mar 2015

Conference

Conference19th Middle East Oil and Gas Show and Conference 2015
Abbreviated titleMEOS 2015
CountryBahrain
CityManama
Period8/03/1511/03/15

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Fuel Technology

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  • Cite this

    Sohrabi, M. S., Mahzari, P., Farzaneh, S. A., Mills, J. R., Tsolis, P., & Ireland, S. (2015). Novel insights into mechanisms of oil recovery by low salinity water injection. In SPE Middle East Oil and Gas Show and Conference, MEOS, Proceedings (pp. 2491-2508). Society of Petroleum Engineers. https://doi.org/10.2118/172778-MS