PETROMAKS2-Stort program petroleum

To increase oil production after primary recovery has ended, secondary and tertiary recovery methods have to be applied. The secondary methods are mainly based on injecting fluids to increase reservoir pressure, while in tertiary methods the mobility of t he fluids is increased by heating, injection of surfactants, or flooding with carbon dioxide. The wettability of the reservoir influences the residual oil saturation, the relative permeability and capillary pressure, and it is therefore a very important p roperty of reservoir rocks. For enhanced oil recovery using secondary and tertiary recovery methods it is therefore important to accurately characterize the reservoir with respect to wettability, and also to understand the underlying mechanisms behind the varying wettability properties. Nuclear Magnetic Resonance (NMR) spectroscopy is a technique with unfulfilled potential for providing wettability data with more details, and can be used to gain increased understanding of liquid-surface interactions in reservoir rock core materials. The sensitivity and specificity of the existing low-field NMR methods for wettability characterization can be improved through the use of novel multidimensional-NMR measurements of relaxation and diffusion. We present two low-field NMR methods that we believe can be used for this purpose. High-field MAS-NMR is an under-utilized method for investigating the liquid-surface interactions that influence the observed wettablility properties. By investigating novel approaches t o proper sample preparations, we believe that high-field MAS-NMR can become a valuable technique for wettability investigations. Our approach is to combine the use of low-field NMR and high-field NMR methods in order to establish an improved experimental procedure for characterizing reservoir rock core wettability that is less time consuming, more detailed, and that leads to an increased understanding of the underlying mechanisms that determine the wettability.