Generation of isotherm datasets for reservoir volumetric estimation

A non-transitory computer-readable medium storing instructions, that, when executed by a processor, cause the processor to perform operations, the operations comprising:

• running a molecular dynamics simulation of a fluid-rock model of a first reservoir system at a plurality of pressures, wherein the fluid-rock model comprises a fluid that is at least partially adsorbed in the first reservoir system at one or more pressures of the plurality of pressures;
• determining a plurality of isothermal density profiles of the fluid in the first reservoir system, in association with the plurality of pressures using a result of the molecular dynamics simulation, wherein determining the plurality of isothermal density profiles comprises:
• defining a plurality of layers comprising a first layer defined adjacent to a pore wall and a second layer that is defined adjacent to the first layer, such that the first layer is between the second layer and the pore wall;
• and
• determining respective densities of the respective plurality of layers based on a number of molecules that are in the respective plurality of layers;
• determining a first gas accumulation of the fluid in the first reservoir system for the plurality of isothermal density profiles, wherein the first gas accumulation is at least partially a function of a pore surface area of a sample of the first reservoir system, wherein:
• the sample was captured from a wellbore of the first reservoir system;
• and
• the first gas accumulation of the fluid that is determined is used for one or more of exploration or production efforts;
• and
• determining, using the molecular dynamics simulation, a first plurality of gas accumulation versus pressure curves based at least partially upon the first gas accumulation and at least one of pressure, temperature, composition, or pore surface area as inputs to the molecular dynamics simulation, wherein each of the first plurality of gas accumulation versus pressure curves corresponds to a different pore surface area;
• wherein determining the plurality of isothermal density profiles further comprises:
• defining a volume operator having a dimension that is less than a diameter of one of the molecules of the fluid;
• determining the number of molecules at distance intervals from the pore wall, wherein the distance intervals have a width substantially equal to the dimension of the volume operator;
• and
• determining one of the plurality of isothermal density profiles, in association with one of the plurality of pressures, based on the number of molecules determined for each of the distance intervals;
• and
• wherein the layers have a width along a pore half-length that is larger than the dimension of the volume operator, and wherein the first layer is between the second layer and the pore wall along the pore half-length.

A computing system comprising:

• one or more processors;
• and
• a memory system comprising one or more computer-readable media storing instructions that, when executed by at least one of the one or more processors, cause the computing system to perform operations, the operations comprising:
• running a molecular dynamics simulation of a fluid-rock model of a first reservoir system at a plurality of pressures, wherein the fluid-rock model comprises a fluid that is at least partially adsorbed in the first reservoir system at one or more pressures of the plurality of pressures;
• determining a plurality of isothermal density profiles of the fluid in the first reservoir system, in association with the plurality of pressures using a result of the molecular dynamics simulation, wherein determining the plurality of isothermal density profiles comprises:
• defining a plurality of layers comprising a first layer defined adjacent to a pore wall and a second layer that is defined adjacent to the first layer, such that the first layer is between the second layer and the pore wall;
• and
• determining respective densities of the respective plurality of layers based on a number of molecules that are in the respective plurality of layers;
• determining a first gas accumulation of the fluid in the first reservoir system for the plurality of isothermal density profiles, wherein the first gas accumulation is at least partially a function of a pore surface area of a sample of the first reservoir system, wherein:
• the sample was captured from a wellbore of the first reservoir system;
• and
• the first gas accumulation of the fluid that is determined is used for one or more of exploration or production efforts;
• and
• determining, using the molecular dynamics simulation, a first plurality of gas accumulation versus pressure curves based at least partially upon the first gas accumulation and at least one of pressure, temperature, composition, or pore surface area as inputs to the molecular dynamics simulation, wherein each of the first plurality of gas accumulation versus pressure curves corresponds to a different pore surface area
• wherein determining the plurality of isothermal density profiles further comprises:
• defining a volume operator having a dimension that is less than a diameter of one of the molecules of the fluid;
• determining the number of molecules at distance intervals from the pore wall, wherein the distance intervals have a width substantially equal to the dimension of the volume operator;
• and
• determining one of the plurality of isothermal density profiles, in association with one of the plurality of pressures, based on the number of molecules determined for each of the distance intervals;
• and
• wherein the layers have a width along a pore half-length that is larger than the dimension of the volume operator, and wherein the first layer is between the second layer and the pore wall along the pore half-length.