Accommodating non-Darcian effects of slip flow and Knudsen diffusion on gas flow for use in reservoir simulations

A non-transitory, computer-readable medium storing one or more instructions for integrating slip flow and Knudsen diffusion (SFKD) into a reservoir simulation, the instructions being executable by a computer system to perform operations comprising:

• adjusting a rock sample to a set of different pressures, the rock sample being representative of rocks located at a reservoir being simulated in the reservoir simulation;
• causing application, to the rock sample at each of the different pressures of the set, gases using single-component and bulk-phase gas viscosity values;
• receiving measurements, for at each of the different pressures of the set, of respective permeability values of the rock sample, the permeability values being a function of the single-component and the bulk-phase gas viscosity values;
• performing, based on the measuring, SFKD adjustments to each gas component value of a reservoir gas, the adjustments representing composite SFKD effects for realistic gas mixtures for the reservoir gas;
• determining for each adjusted gas component of the reservoir gas, porosities including mean free paths for a range of temperatures and pressures encompassing conditions for both reservoir simulation input and the measured permeability values;
• determining a characteristic pore radius for the rock sample using the measured permeability values and the determined porosities;
• determining using the measured permeability values, viscosity adjustment factors for a predefined range of temperatures and pressures;
• determining using the viscosity adjustment factors, adjusted gas viscosities for the realistic gas mixtures for the reservoir gas, the gas viscosities being adjusted for the predefined range of temperatures and pressures and the measured permeability values;
• executing, by a reservoir simulator, the reservoir simulation using the adjusted gas viscosities, the reservoir simulation having an increased accuracy relative to a reservoir simulation that does not capture SFKD effects;
• based on executing the reservoir simulator, generating a prediction for an amount of production from one or more existing fractured wells at the reservoir;
• based on the prediction, selecting one or more locations in the reservoir;
• and
• updating production operations at the reservoir by causing performance of hydraulic fracturing at the one or more locations.

A computer-implemented system, comprising:

• one or more sensors configured to measure permeability values for rock samples;
• one or more processors;
• and
• a non-transitory computer-readable storage medium coupled to the one or more processors and storing programming instructions for integrating slip flow and Knudsen diffusion (SFKD) into a reservoir simulation, instructions being for execution by the one or more processors, the programming instructions instructing the one or more processors to perform operations comprising:
• adjusting a rock sample to a set of different pressures, the rock sample being representative of rocks located at a reservoir being simulated in the reservoir simulation;
• causing application, to the rock sample at each of the different pressures of the set, gases using single-component and a bulk-phase gas viscosity values;
• receiving measurements from the one or more sensors for at each of the different pressures of the set, respective permeability values of the rock sample the permeability values being a function of the single-component and the bulk-phase gas viscosity values;
• performing, based on the measuring, SFKD adjustments to each of the gas component gas viscosity value and the bulk gas viscosity value of a reservoir gas, the adjustments representing composite SFKD effects for realistic gas mixtures for the reservoir gas;
• determining for each adjusted gas component of the reservoir gas, porosities including mean free paths for a range of temperatures and pressures encompassing conditions for both reservoir simulation input and the measured permeability values;
• determining a characteristic pore radius for the rock sample using the measured permeability values and the determined porosities;
• determining using the measured permeability values, viscosity adjustment factors for a predefined range of temperatures and pressures;
• determining using the viscosity adjustment factors, adjusted gas viscosities for the realistic gas mixtures for the reservoir gas, the gas viscosities being adjusted for the predefined range of temperatures and pressures and the measured permeability values;
• and
• executing, by a reservoir simulator, the reservoir simulation using the adjusted gas viscosities, the reservoir simulation having an increased accuracy relative to a reservoir simulation that does not capture SFKD effects;
• based on executing the reservoir simulator, generating a prediction for an amount of production from one or more existing fractured wells at the reservoir;
• based on the prediction, selecting one or more locations in the reservoir;
• and
• updating production operations at the reservoir by causing performance of hydraulic fracturing at the one or more locations.