Towards faster Amott index measurement: Amott Express Technique

Wettability of oil reservoirs is a crucial parameter influencing hydrocarbon recovery. The Amott and USBMindex are commonly used to evaluate the wettability of reservoir rocks. However, traditional methods oftenrequire cell loading/unloading operations between different phases of the experiment, which imposeshandling and therefore more errors and uncertainties. In this paper we present the Amott Express technique,which uses a single cell designed to be compatible with Nuclear Magnetic Resonance (NMR) imaging toperform all stages of the experimental cycle from spontaneous imbibition to forced secondary drainage. Theuse of D2O brine instead of conventional H2O brine allows the monitoring of oil saturation changes duringthe different phases. NMR provides a precise evaluation of saturation variations along the rock sampleenabling the calculation of a far more precise Amott index, as it helps to deal with the presence of capillaryend effects. Another benefit is reducing the experimental duration due to less handling and using viscoussweeping for forced steps. The proof of feasibility of the Amott Express is confirmed with the resultsobtained on a reservoir rock sample. In addition, keeping the same rock inlet throughout the corefloodsallows the approximation of inlet pressure to Capillary pressure, which is then associated with inlet facesaturation (evaluated thanks to NMR). This approach provides Pc curves for each step, allowing theevaluation of the USBM index. The Amott Express Technique offers a practical and reliable solution forobtaining Amott and USBM indices while minimizing errors and uncertainties associated with cellexchange.