Porosity Measurement Using Image Analysis Techniques

Spontaneous imbibition is perhaps the most important phenomenon in oil recovery from fractured and low permeability tight gas reservoirs.  Air-water spontaneous imbibition experiments were conducted using low permeability heterogenous limestone core plugs. The interfacial tension was changed by adding differing amounts of alcohol to water.  It was observed that the true residual saturation of gas is very small for all cases.  A much larger pseudo-residual saturation was achieved early in the imbibition stage but gas continued to be produced at extremely low rates until the true saturation was reached.  The gas-air spontaneous imbibition performance was modelled using a mathematical model where the porous medium is represented as a bundle of equal but turtous capillary tubes. Input data for this model was obtained from thin sections using a state of the art image processing system and a computerized microscope. It was observed that the model succesfully explained the imbibition process in samples where pores with varying circularity were present.  Average number of pore throats meeting at one pore in the pore skeleton (coordination number) was less than six for all cases. 

Related Publications

• 1.      Hatiboglu, C.U., Karaaslan U, and Akın S.: “Spontaneous Imbibition in Low Permeability Carbonates” 2003 International Symposium of the Society of Core Analysts, 21-24 Sept., 2003, Pau, France.
• 2.      Hatiboğlu, C.U. and Akın S.: “A new computerized moving stage for optical microscopes”, Computers & Geosciences, 30, 5, 471-481, 2004.
• 3.      Hatiboglu, C.U., Karaaslan U, and Akın S.: “Spontaneous Imbibition in Low Permeability Carbonates” Energy Sources, 27, 839-846, 2005.