Caprock Integrity Assessment via Helium Concentration Deviations

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Solution Overview

Problem

The integrity of caprocks in geologic sequences is uncertain for hydrogen storage or sequestration, as they have not been tested for gas confinement over geological periods, and hydrogen's smaller molecule size allows greater penetration, making existing methods inadequate for assessing caprock defects.

Innovation Solution

A method utilizing helium concentration as an indicator for potential hydrogen leakage is employed. Helium, with similar penetration ability to hydrogen, is measured in subsurface fluids collected above, within, and below the caprock. Deviations in helium concentration between wells indicate caprock defects, allowing for the assessment of caprock integrity and suitability for hydrogen storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional caprock assessment methods are used, then existing knowledge from methane storage is applied, but hydrogen leakage risk increases due to hydrogen's smaller molecule size and greater penetration ability

Engineering Contradiction:

Improvecaprock integrity for hydrogen storageVSAvoidhydrogen leakage through caprock defects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses helium as an intermediary substance to assess caprock integrity. Helium, being a small inert gas molecule similar in size to hydrogen, serves as a proxy to detect potential leakage pathways that would also allow hydrogen to escape. By measuring helium concentrations in subsurface fluids and comparing them across multiple wells, the method identifies caprock defects without directly testing hydrogen permeability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a model system using helium that replicates the penetration behavior of hydrogen through caprock. Since helium and hydrogen have similar molecular sizes and penetration abilities, assessing helium distribution patterns provides a copy or proxy measurement of how hydrogen would behave, allowing indirect evaluation of caprock suitability for hydrogen storage.

Inventive Principle:

Principle #26Copying

2Measurement precision

If multiple wells are drilled to assess caprock integrity, then measurement accuracy improves through comparative analysis, but drilling costs and time increase

Engineering Contradiction:

Improvehelium concentration measurement for defect detectionVSAvoidtime required to drill multiple wells and collect samples

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent employs a grid pattern of multiple wells drilled to specific depths above, within, and below the caprock. This excessive sampling approach ensures comprehensive coverage of the caprock structure, allowing detection of even localized defects. By drilling more wells than the minimum single well, the method achieves superior measurement precision through spatial comparison of helium concentrations across the formation.

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method effectively assesses caprock defects by identifying helium concentration deviations, thereby determining the integrity and suitability of geologic sequences for hydrogen storage, preventing unnecessary investment in unsuitable formations.

Implementation Method 1

These quantities of helium may then gradually migrate upward within geologic sequences until being captured with other gaseous species below a suitable caprock

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

These quantities of helium may then gradually migrate upward within geologic sequences until being captured with other gaseous species below a suitable caprock

Methodology Applied

Scientific EffectAdvection: Advection

Implementation Method 3

Quantities of helium, and in particular the helium-4 isotope, may originate in subsurface formations from the radioactive decay of uranium and thorium into alpha particles

Methodology Applied

Scientific EffectRadioactive decay: Radioactive Decay

Data Source

PatentUS20250116647A1Methods of assessing a caprock in a geologic sequence for caprock defects

Publication Date: 2025.04.10 SAUDI ARABIAN OIL CO

AI summary

A method of assessing a caprock for caprock defects comprises drilling a first well into a geologic sequence, the geologic sequence comprising a first subsurface formation, the caprock positioned above the first subsurface formation, and a second subsurface formation positioned above the caprock; sampling subsurface fluids of the geologic sequence for helium concentration within the second subsurface formation, within the caprock, and within the first subsurface formation; drilling a second well into the geologic sequence a pre-determined distance away from the first well; sampling the subsurface fluids for the helium concentration within the second subsurface formation, within the caprock, and within the first subsurface formation through the second well; determining whether a deviation exists between the helium concentration at the first well and at the second well, the deviation indicating the caprock defect is present; and halting further drilling into the geologic sequence upon determining the caprock defect is present.