Pore-scale numerical modeling of petrophysical properties with applications to hydrocarbon-bearing organic shale
| dc.contributor.advisor | Torres-Verdín, Carlos | |
| dc.contributor.advisor | Sepehrnoori, Kamy, 1951- | |
| dc.creator | Shabro, Vahid | en |
| dc.date.accessioned | 2014-01-21T21:21:34Z | en |
| dc.date.accessioned | 2017-05-11T22:41:08Z | |
| dc.date.available | 2017-05-11T22:41:08Z | |
| dc.date.issued | 2013-12 | en |
| dc.date.submitted | December 2013 | en |
| dc.date.updated | 2014-01-21T21:21:34Z | en |
| dc.description | text | en |
| dc.description.abstract | The main objective of this dissertation is to quantify petrophysical properties of conventional and unconventional reservoirs using a mechanistic approach. Unconventional transport mechanisms are described from the pore to the reservoir scale to examine their effects on macroscopic petrophysical properties in hydrocarbon-bearing organic shale. Petrophysical properties at the pore level are quantified with a new finite-difference method. A geometrical approximation is invoked to describe the interstitial space of grid-based images of porous media. Subsequently, a generalized Laplace equation is derived and solved numerically to calculate fluid pressure and velocity distributions in the interstitial space. The resulting macroscopic permeability values are within 6% of results obtained with the Lattice-Boltzmann method after performing grid refinements. The finite-difference method is on average six times faster than the Lattice-Boltzmann method. In the next step, slip flow and Knudsen diffusion are added to the pore-scale method to take into account unconventional flow mechanisms in hydrocarbon-bearing shale. The effect of these mechanisms is appraised with a pore-scale image of Eagle Ford shale as well as with several grain packs. It is shown that neglecting slip flow in samples with pore-throat sizes in the nanometer range could result in errors as high as 2000% when estimating permeability in unconventional reservoirs. A new fluid percolation model is proposed for hydrocarbon-bearing shale. Electrical conductivity is quantified in the presence of kerogen, clay, hydrocarbon, water, and the Stern-diffuse layer in grain packs as well as in the Eagle Ford shale pore-scale image. The pore-scale model enables a critical study of the [delta]LogR evaluation method commonly used with gas-bearing shale to assess kerogen concentration. A parallel conductor model is introduced based on Archie's equation for water conductivity in pores and a parallel conductive path for the Stern-diffuse layer. Additionally, a non-destructive core analysis method is proposed for estimating input parameters of the parallel conductor model in shale formations. A modified reservoir model of single-phase, compressible fluid is also developed to take into account the following unconventional transport mechanisms: (a) slip flow and Knudsen diffusion enhancement in apparent permeability, (b) Langmuir desorption as a source of gas generation at kerogen surfaces, and (c) the diffusion mechanism in kerogen as a gas supply to adsorbed layers. The model includes an iterative verification method of surface mass balance to ensure real-time desorption-adsorption equilibrium with gas production. Gas desorption from kerogen surfaces and gas diffusion in kerogen are the main mechanisms responsible for higher-than-expected production velocities commonly observed in shale-gas reservoirs. Slip flow and Knudsen diffusion marginally enhance production rates by increasing permeability during production. | en |
| dc.description.department | Petroleum and Geosystems Engineering | en |
| dc.format.mimetype | application/pdf | en |
| dc.identifier.uri | http://hdl.handle.net/2152/22902 | en |
| dc.language.iso | en_US | en |
| dc.subject | Pore-scale model | en |
| dc.subject | Finite-difference | en |
| dc.subject | Shale-gas | en |
| dc.subject | Hydrocarbon-bearing shale | en |
| dc.subject | Electrical resistivity | en |
| dc.subject | Permeability | en |
| dc.subject | FIB-SEM | en |
| dc.subject | Lattice-Boltzmann method | en |
| dc.subject | Knudsen diffusion | en |
| dc.subject | Langmuir desorption | en |
| dc.subject | Diffusion in kerogen | en |
| dc.subject | Organic matter | en |
| dc.title | Pore-scale numerical modeling of petrophysical properties with applications to hydrocarbon-bearing organic shale | en |