Caprock analysis methods and systems
AssigneeSaudi Arabian Oil Company
InventorsHui-Hai Liu, Jilin Jay Zhang
Life of this patent
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Abstract
A method of analyzing a caprock of an aquifer includes determining, using a laboratory measurement device, a threshold hydraulic gradient of the caprock at which brine flows vertically in the caprock. The method further includes determining a breakthrough pressure of the caprock, wherein the breakthrough pressure reflects a difference between a CO2 pressure in the aquifer and a brine pressure in the caprock. The method further includes calculating, via a computing system that includes one or more hardware processors, an effective breakthrough pressure of the caprock based on the threshold hydraulic gradient and the breakthrough pressure, wherein the effective breakthrough pressure accounts for non-Darcy flow of the brine within the caprock.
Claims8
A method of analyzing a caprock positioned above an aquifer, the method comprising:
- determining, using a laboratory measurement device and according to a steady-state flow protocol, a threshold hydraulic gradient of the caprock at which brine flows vertically in the caprock;
- determining a breakthrough pressure of the caprock, wherein the breakthrough pressure comprises a difference between a CO2 pressure in the aquifer and a brine pressure in the caprock;
- determining, using a field characterization device, a thickness of the caprock as a difference between a top surface of the caprock and a bottom surface of the caprock that defines an interface between the caprock and the aquifer;
- collecting, using a field collection device, a sample of the caprock from a bottom end region of the caprock for analysis;
- and
- calculating, via a computing system that comprises one or more hardware processors, an effective breakthrough pressure of the caprock based on the threshold hydraulic gradient and the breakthrough pressure, wherein the effective breakthrough pressure accounts for non-Darcy flow of the brine within the caprock,
- wherein the breakthrough pressure is calculated, via the computing system, based on a CO2-brine interfacial tension, a CO2 contact angle in the caprock, and a radius of a pore threshold in the caprock.
A caprock analysis system for analyzing a caprock positioned above an aquifer, the caprock analysis system comprising:
- a laboratory measurement device configured to measure, according to a steady-state flow protocol, a threshold hydraulic gradient of the caprock at which brine flows vertically in the caprock;
- a device configured to determine a breakthrough pressure of the caprock, wherein the breakthrough pressure comprises a difference between a CO2 pressure in an aquifer beneath the caprock and a brine pressure in the caprock;
- a field characterization device configured to determine a thickness of the caprock as a difference between a top surface of the caprock and a bottom surface of the caprock that defines an interface between the caprock and the aquifer;
- a field collection device configured to collect a sample of the caprock from a bottom end region of the caprock for analysis;
- and
- a computing system operable to calculate an effective breakthrough pressure of the caprock based on the threshold hydraulic gradient and the breakthrough pressure, wherein the effective breakthrough pressure accounts for non-Darcy flow of the brine within the caprock,
- wherein the device comprises one or more hardware processors of the computing system, and
- wherein the breakthrough pressure is calculated, via the computing system, based on a CO2-brine interfacial tension, a CO2 contact angle in the caprock, and a radius of a pore threshold in the caprock.
Dependencies are inferred from the claim text.