Ian F. Macdonald 

BEng, Daltech, Dalhousie (formerly TUNS or Nova Scotia Technical College); PhD, Wisconsin 

The  first software to reconstruct the pore structure of an actual porous medium in computer memory using data from serial sections of a sample of the medium has been developed and used to reconstruct the pore structure of a relatively homogeneous porous medium (Berea sandstone). The porous medium has been characterized - that is, pore geometry (pore body size distribution and pore throat size distribution)and the topology of the pore network (pore coordination number distribution) have been determined for the reconstructed medium. 

Current objectives include:

i) extending the three-dimensional reconstruction techniques to apply to a sample containing solidified wetting and nonwetting phases (brine-oil) following an immiscible displacement process in order to determine the distribution of the wetting and nonwetting phases within the reconstructed medium,
ii) characterizing the 3-D properties more fully by investigating the existing data bank to establish and characterize the actual shapes of the irregular pore bodies and of the larger pore throats,
iii) improving the 3-D reconstruction software to do better at estimating pore throat size distributions, and iv) investigating the strengths and weaknesses of our reconstruction approach versus the alternate approaches to reconstruction subsequently developed by other researchers with the aim of developing improved software. Several of these studies will be integrated with the stochastic modeling studies described below.

A stochastic procedure using probability functions and autocorrelation functions obtained simply and rapidly from two-dimensional data has been being used to create three-dimensional model pore structures. The models have similar 2-D properties to the actual medium, and we provided the first validation at the 3-D level by reconstructing and characterizing the models using the reconstruction software described above, and comparing the results with those for the reconstructions from serial section data of the actual medium.The three-dimensional pore structure data from the stochastic modeling and reconstruction have been input into network models by other researchers at Waterloo in a  project to develop a computer enhanced core analysis for the petroleum industry. Improvements are required in this first generation reconstruction and stochastic modeling software for its potential to be realized.

Current objectives include:

i) improving the stochastic modeling software to incorporate additional 2-D accessible statistical functions so that the model media adequately predict a wider range of 3-D properties of the medium, and
ii) using our 3-D reconstruction and modeling capability in an attempt to develop new 2-D methods of reliably estimating 3-D properties (probably involving the new unbiased stereological tools like the disector) which are less computer intensive than the full 3-D approach.

• H.Q. Zhao and I.F. Macdonald, "An Unbiased and Efficient      Procedure for 3-D Connectivity Measurement as Applied to      Porous Media", J. Microscopy, 172, 157-162(1993). 

•  M.J. Kwiecien, I.F. Macdonald, and F.A.L. Dullien,      "Three-Dimensional Reconstruction of Porous Media from Serial    Section Data", J. Microscopy 159, 343-359(1990). 

•  I.F. Macdonald, G.D. Yadav, I. Chatzis, and F.A.L. Dullien,      "Two-Phase Flow in Porous Media: Obtaining Sharp Digitized     Images of Serial Sections for Subsequent Quantitative Analysis",     J. Microscopy, 150, 191-198 (1988). 

• I.F. Macdonald, P.M. Kaufmann and F.A.L. Dullien,     "Quantitative Image Analysis of Finite Porous Media. II. Specific     Genus of Cubic Lattice Models and Berea Sandstone", J.      Microscopy, 144, 297-316 (1986). 

• I.F. Macdonald, P.M. Kaufmann and F.A.L. Dullien,      "Quantitative Image Analysis of Finite Porous Media. I.      Development of Genus and Pore Map Software", J. Microscopy,     144, 277-296 (1986).