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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

3D Visualisation of Trapped Hydrocarbons in Carbonates from the Pore Scale: Exploring the Residual Hydrocarbon Phase after Secondary and Tertiary Flooding

Mark Knackstedt1; Munish Kumar1; Tim Senden1; Rob Sok2

(1) Australian National University, Canberra, ACT, Australia.

(2) Digital Core Laboratories, Canberra, ACT, Australia.

At the conclusion of flooding in an oil- or gas-bearing carbonate reservoir, a significant fraction of the original hydrocarbon in place remains in the swept region as trapped residual phase. In addition to the amount of trapped phase, its microscopic distribution within the pore space of a reservoir rock is important to gain a better understanding of recovery mechanisms and for the design and implementation of improved or enhanced recovery processes. Despite the importance of the pore scale structure and distribution of residual oil, little quantitative information is currently available. This study presents a robust method to obtain this critical information.

Residual saturation visualization is undertaken in core material at the pore scale via microtomographic imaging. We utilize a new technique for imaging the pore-scale distribution of fluids in reservoir cores in three dimensions. The method allows reservoir core material to be imaged after different stages of flooding; e.g. after secondary and tertiary floods. Core flooding can also be performed under different wettability conditions, saturation states and flooding rates.

Although considerable attention has been paid to the subject of residual oil structure, the amount of quantitative experimental information on the structure of the residual oil phase in reservoir core material is limited. The detailed structure of the residual trapped phase is described. This information is correlated to pore structural information from the 3D image data (pore geometry, connectivity), mineralogy and rock type. These results provide an important platform for the testing and calibration of pore scale modelling efforts for multiphase flow.

This detailed pore scale information of the residual oil saturation is crucial to the design and implementation of improved recovery processes and can be related to conditions required for mobilization of residual oil. Oil recovery mechanisms are directly tested and the differences in the habitat of the residual fluids under different conditions are directly quantified.