“Smart Water” Flooding in Carbonates and Sandstones: A New Chemical Understanding of the EOR-potential - Tor Austad, University of Stavanger

Abstract:

Provided water is accessible, most of the sandstone oil reservoirs are water flooded to maximize oil recovery. More than 50 % of the proven oil resources are, however, present in carbonate reservoirs. Even though carbonate reservoirs are regarded to be more complicated to water flooding due to lower water wetness, low permeability, and natural fractures, large carbonate reservoirs both in the North Sea and in the Middle East are today successfully flooded with seawater.

During the last 15 years, new research has pointed out how important the wetting condition of the porous medium is for obtaining good displacement of the oil by the injected water. The initial wetting condition of an oil reservoir, which has been established during millions of years, may not be at the optimum for oil displacement by water. When injecting a "Smart Water" with different ion composition than the initial formation water, it is possible to modify the wetting condition of the reservoir in a favorable way, which can have dramatic effects on oil recovery, especially in carbonates. In order to take benefit of "Smart Water" it is important to have a good knowledge of the chemical process taking place at the rock surface.

New chemical understanding about water based EOR by wettability modification both in carbonates and sandstones will be presented, and the EOR-potential will be verified. The conditions for maximizing the EOR-effect by "Smart Water" will be discussed from lab experiments and field tests. Economically, it is important that oil reservoirs are flooded with the most optimum water from the very beginning.

PS! The one idea that I want the members to take away from the lecture is: "The oil recovery is not independent on the type of water injected. The effects on oil recovery can be dramatic, especially for carbonates."

Biography:

Tor Austad is a Professor in reservoir chemistry at the U. of Stavanger, Norway, and he has served as a consultant for different oil companies and research institutes. He holds MS and PhD degrees in physical chemistry from U. of Bergen. He has been connected to petroleum education and research for more than 35 years. He served as member and chairman of the Petroleum and Chemistry groups of the Norwegian Research Council, NFR, during 1983-1989. He has published more than 100 journal papers in addition to a large number of presentations on international symposia and supervised 15 PhD students. He has participated in national EOR-programs (SPOR 1986-1992, RUTH 1992-96), and he got the SPOR research price.

Experience in research activities within: Traditional physical chemistry/reaction kinetics; PVT-properties of reservoir fluids; Surface chemistry related to EOR; water based EOR by wettability alteration in carbonates and sandstones. Austad recently received the Norwegian Petroleum Directorate, NPD, IOR reward for 2010.