Modeling gas desorption in a subsurface reservoir
Systems and methods for modeling gas desorption in a subterranean reservoir include measuring a gas sorption parameter using a crushed core sample from the subterranean reservoir; computing a gas storage capacity of the subterranean reservoir at an initial reservoir pressure based on the gas sorption parameter; generating a three-dimensional (3D) distribution of total organic carbon (TOC) in the subterranean reservoir; estimating a 3D distribution of original adsorbed gas in place of the subterranean reservoir by correlating the gas storage capacity with the 3D distribution of TOC; and predicting the amount of gas desorbed from the subterranean reservoir as the reservoir is depleted.
1. A method for modeling gas desorption in a subterranean reservoir, the method comprising:
measuring a gas sorption parameter using a crushed core sample from the subterranean reservoir;
computing a gas storage capacity of the subterranean reservoir at an initial reservoir pressure based on the gas sorption parameter;
generating a three-dimensional (3D) distribution of total organic carbon (TOC) in the subterranean reservoir;
estimating a 3D distribution of original adsorbed gas in place of the subterranean reservoir by correlating the gas storage capacity with the 3D distribution of TOC; and
predicting the amount of gas desorbed from the subterranean reservoir as the reservoir is depleted.
2. The method of claim 1 , further comprising:
defining a desorption pressure at which gas in the subterranean reservoir begins to desorb.
3. The method of claim 2 , wherein, the desorption pressure is user-defined for each cell in the 3D distribution of original adsorbed gas in place.
4. The method of claim 2 , wherein the subterranean reservoir is under saturated.
5. The method of claim 2 , wherein the subterranean reservoir is saturated.
6. The method of claim 2 , wherein the desorption pressure is estimated based on the measuring.
7. The method of claim 1 , wherein the predicting comprises using an isotherm scaled by comparing a Langmuir isotherm with the 3D distribution of original adsorbed gas in place.
8. The method of claim 1 , further comprising producing hydrocarbons from the subterranean reservoir.
9. One or more non-transitory machine-readable storage devices storing instructions for modeling gas desorption in a subterranean reservoir, the instructions being executable by one or more processing devices to cause performance of operations comprising:
accessing, from a data store, values of a measured gas sorption parameter for the subterranean reservoir;
computing a gas storage capacity of the subterranean reservoir at an initial reservoir pressure based on the values of the measured gas sorption parameter;
generating a three-dimensional (3D) distribution of total organic carbon (TOC) in the subterranean reservoir;
estimating a 3D distribution of original adsorbed gas in place (OAGIP) of the subterranean reservoir by correlating the gas storage capacity with the 3D distribution of TOC; and
predicting the amount of gas desorbed from the subterranean reservoir as the reservoir is depleted.
10. The non-transitory machine-readable storage devices of claim 9 , wherein the operations further comprise:
defining a desorption pressure at which gas in the subterranean reservoir begins to desorb.
11. The non-transitory machine-readable storage devices of claim 10 , wherein, the desorption pressure is user defined for each cell in the 3D distribution of OAGIP.
12. The non-transitory machine-readable storage devices of claim 10 , wherein the subterranean reservoir is under saturated.
13. The non-transitory machine-readable storage devices of claim 10 , wherein the subterranean reservoir is saturated.
14. The non-transitory machine-readable storage devices of claim 10 , wherein the desorption pressure is estimated based on a measured gas sorption property.
15. The non-transitory machine-readable storage devices of claim 9 , wherein the predicting comprises using an isotherm scaled by comparing a Langmuir isotherm with the 3D distribution of original adsorbed gas in place.
16. A system for modeling gas desorption of a subterranean reservoir, the system comprising:
at least one processor; and
a memory storing instructions that, when executed by the at least one processor, cause the at least one processor to perform operations comprising:
accessing, from a data store, values of a measured gas sorption parameter for the subterranean reservoir;
computing a gas storage capacity of the subterranean reservoir at an initial reservoir pressure based on the values of the measured gas sorption parameter;
generating a three-dimensional (3D) distribution of total organic carbon (TOC) in the subterranean reservoir;
estimating a 3D distribution of original adsorbed gas in place (OAGIP) of the subterranean reservoir by correlating the gas storage capacity with the 3D distribution of TOC; and
predicting the amount of gas desorbed from the subterranean reservoir as the reservoir is depleted.
17. The system of claim 16 , wherein the operations further comprise:
defining a desorption pressure at which gas in the subterranean reservoir begins to desorb.
18. The system of claim 17 , wherein, the desorption pressure is user-defined for each cell in the 3D distribution of original adsorbed gas in place.
19. The system of claim 17 , wherein the subterranean reservoir is under saturated.
20. The system of claim 16 , wherein the predicting comprises using an isotherm scaled by comparing a Langmuir isotherm with the 3D distribution of original adsorbed gas in place.