Estimation of conductivity for nanoporous materials
| DWPI Title: Method for operating computer system to calculate electrical conductivity in clay mineral in shaly sand in oil and gas industry, involves calculating ion conductivities for species of counterions from self-diffusion coefficients |
| Abstract: Methods and systems for estimating conductivity of clay mineral systems, and for applying the estimates in larger-scale analysis. Conductivity of the clay may be estimated by constructing a molecular model of an anhydrous charge-neutral clay, and then assigning a charge density by substitution of ions in the model of the clay structure. Counterions are inserted for charge neutrality, and water molecules are added to the model to reflect a selected level of hydration. Following assignment of force-field coefficients, molecular dynamics simulation provides data from which diffusion coefficients can be estimated. Application of the Nernst-Einstein relationship to the diffusion coefficients of the counterions provides the ion conductivity of the clay system. This conductivity can be used to derive a formation factor, and can be applied in direct numerical simulation analysis. |
| Use: Method for operating a computer system to calculate electrical conductivity in a clay mineral in shaly sand in an oil and gas industry. |
| Advantage: The method enables performing molecular-level analysis to enable accurate analysis of nanoscale formation components beyond capability of conventional approaches such as archie's Relationship. |
| Novelty: The method involves assigning force field parameters to molecular representation in combination with boundary conditions. A computer system (20) is operated to perform molecular dynamics simulation of equations of motion over simulation time interval and determine positional coordinates of counterions in the representation at times during the simulation time interval. Self-diffusion coefficients for species of counterions are calculated from the positional coordinates at the times. Ion conductivities are calculated for species of counterions from the self-diffusion coefficients. |
| Filed: 12/10/2014 |
| Application Number: US14566520A |
| Tech ID: SD 13388.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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