The Challenge

Several hypotheses regarding the mechanism involved with reduced salinity waterflood oil recovery have been proposed, but further research is need to fully understand the mechanism. Oilfield fluids contain a complex mixture of different components including oil, water, clay and sand. Here, clay and model silica (“sand”) particles were suspended in organic solvents (“oil”) in the presence of salt and water to model an oilfield fluid.

The Solution

Sophisticated physical chemistry techniques were needed to detect water layers at the particle interface. The research team performed small angle X-ray scattering using beamline I22 at Diamond to measure very thin water layers on the surface of the particles at the Angstrom level. Complementary neutron scattering measurements were also performed at ISIS and the ILL in Grenoble. Small angle scattering experiments helped the team to detect and characterise thin water layers surrounding both sand-like and clay-like particles. As the ionic strength of the water falls (lower salinity), the size of the water layer changes.

The Benefits

The conclusions provide support for the mechanism by which BP believe low salinity waterflooding is able to enhance oil recovery. Further work to deepen this understanding is being performed, this technique provides an avenue to understand how to control the process.