Improved Oil Recovery by Low Salinity Waterflooding: Surface Chemistry and SCAL Studies - Improved Oil Recovery by Low Salinity Waterflooding: Surface Chemistry and SCAL Studies

Improved Oil Recovery by Low Salinity Waterflooding: Surface Chemistry and SCAL Studies

Project Manager: Ole Torsæter, Professor, NTNU

Post-doc/scholar: Nanji Hadia

Project duration: 2008-08-01 to 2011-07-31

Technical contact person in StatoilHydro : Medad T. Tweheyo

Division head: Lars Høier

Project number: 6345

Objective:

The objective of this project is to investigate scopes of low salinity water injection as an improved oil recovery method by SCAL studies and its linkage to the surface chemistry of reservoir rocks. The combination of SCAL and surface chemistry can provide an improved understanding of possible mechanisms of oil recovery during low salinity waterflooding. This information will be useful while addressing the challenges during modelling of low salinity waterflooding process. The future work in the project includes coreflooding experiments using acid and base free Heidrun crude oil to study the effects of acidic and basic components on oil recovery during low salinity waterflooding. Further it has been planned to study the in-situ change in wettabilities during low salinity waterflooding process. Moreover, it has also been planned, if time permits, to perform cryo-SEM study to get an insight into the mechanism of oil displacement by low salinity water.

Status:

Coreflooding experiments were performed to evaluate the effect of wettability on oil recovery during low salinity waterflooding (LSW) as secondary and tertiary recovery processes. Experiments were performed on Berea core plugs with four different wettability conditions ranging from water- to oil- wet. Three synthetic brines viz., SB, 10% SB and 1% SB, of different salinities were used for injection. 10% SB and 1% SB brines were low salinity brines. The results suggest that the neutral wet condition provides the maximum oil recovery for all the salinities considered for secondary and tertiary recovery processes. It was also observed that oil recovery increases with decrease in the salinity of injection brine when LSW is used as secondary recovery process. It was also observed that for water-wet (WW) cores, with decrease in salinity the differential pressure across the core was increased and hence the effective permeability of the core was decreased. For other wettability conditions, the differential pressures were observed to be minimum and maximum for 10% and 1% salinity brines, respectively. Further, clay fines were not observed in the effluents by naked eyes.

Publications: 1 publication

Ashraf, A., Hadia, N. J., Torsæter, O, and Tweheyo, M.T. “Laboratory Investigation of Low Salinity Waterflooding as Secondary Recovery Process: Effect of Wettability”, Paper SPE 129012 to be presented at Oil Gas India Conference to be held at Mumbai India. 20-22 January, 2010.