Improved Oil Recovery by Low Salinity Waterflooding: Surface Chemistry and SCAL Studies - Annual report 2008

Biannual Report VISTA 2008

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

Project director:                Øye Gisle, Ugelstad Laboratory, Trondheim
PhD Scholar:                Farooq Umer
Project Duration:                01-10-07 ------ 30-09-10
Technical Contact Person in Statoil        Tweheyo Medad
Divisional Head:           
Project Number:           

Objet:
The purpose of this project is to investigate the surface chemistry of typical reservoir surfaces where Low Salinity Waterflooding can be used for improved oil recovery, and link this to SCAL studies. This combination will provide advanced understanding of the LSW mechanisms that will be useful when addressing the challenges encountered in flooding processes. The investigation of surface chemistry of reservoir surface will be divided into the following tasks: Task 1: To elucidate how variables such as pH, ion valency, ion concentration and temperature will affect the surface properties (potential distribution and contact angles) of selected model systems and reservoir samples using model brines as well as desalinated sea water. The zeta potentials will be determined, while direct titration experiments will be carried out in order to determine the surface potential. Task 2: Components from crude oil will adsorb onto the reservoir surface. The reservoir samples will be washed in solvent (toluene), and the effluent will be analysed with HPLC. This will provide information about the composition of the adsorbed layer. Task 3: To which extent the particles characterised in the previous tasks will influence the stability of o/w emulsions.

Status:
Crude Oil containing low asphaltene contents produced a stable and small contact angles [CA] as well as low Interfacial tension [IFT]. Changes the surface properties of silica crystals from hydrophilic to hydrophobic have not very large effect on the CA of different oils, where as this change have large effect on the CA of different saline water in the presence of model oils. Change in salinity has no profound effect on the CA measurements. IFT is comparatively low at pH 9 and highest at pH 7. Work related to characterization of solid surfaces is done in contract work and submitted to Statoil. During the 2nd task, asphaltene is adsorbed on silica surface & desorbed by different saline water. In case of Na+, best results are achieved by successive addition of 3.5% - 4000 – 1500 ppm Na and no desorption effect can be seen by injection of 750-350 ppm Na & water. Successive injection of 3.5% and 1500 ppm Ca also produced the best result. Addition of 3.5%-4000 & 1500 ppm Ca has no effect on desorption.

Publications:
Experimental work for two publications is finished. Writing is in progress.


Trondheim, 02.02.2009



Umer Farooq                                Gisle Øye
PhD                                    Project Manager