Residual Hydrocarbon Evaluation for Post-Mature Marine Source Rocks

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Solution Overview

Problem

The evaluation of residual hydrocarbon in post- to over-mature marine source rocks is challenging due to the lack of immature and sub-mature source rock samples, leading to inaccurate assessment of shale oil and gas resources, as existing methods rely on subjective critical conditions and differ significantly across scholars and geological environments.

Innovation Solution

An evaluation method is developed that establishes hydrocarbon generation, expulsion, and retention models for post- to over-mature source rocks by creating profiles based on pyrolysis experiments and fluid inclusion analysis, allowing for the calculation of hydrocarbon retention intensity and residual hydrocarbon without relying on immature to sub-mature samples.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If empirical critical conditions (Ro=0.4%, 0.5%, 0.6%) are used to determine hydrocarbon generation, then the evaluation process is simplified, but the accuracy and scientific rigor of residual hydrocarbon assessment deteriorates

Engineering Contradiction:

Improveevaluation process simplicityVSAvoidresidual hydrocarbon assessment accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the evaluation parameters from empirical Ro values to experimentally determined critical conditions (Roce and Rogen) obtained through pyrolysis experiments and fluid inclusion analysis. This allows accurate determination of hydrocarbon generation and expulsion thresholds specific to each source rock type, resolving the contradiction between simplicity and accuracy by establishing a standardized experimental approach that yields precise, rock-specific parameters.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If immature and sub-mature source rock samples from other basins or strata are used to compensate for lack of samples, then the evaluation can proceed, but the reliability deteriorates due to differences in depositional environment, organic facies, and enrichment conditions

Engineering Contradiction:

Improveevaluation capabilityVSAvoidresidual hydrocarbon prediction accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent enables source rocks to evaluate their own hydrocarbon potential by conducting pyrolysis experiments and fluid inclusion analysis directly on the mature source rock samples themselves. This self-service approach eliminates the need to borrow samples from other basins or strata, ensuring that the evaluation is based on the actual geological characteristics of the target source rocks, thereby maintaining both productivity and reliability.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If subjective definitions of critical conditions are used, then different scholars can conduct evaluations, but the universality and scientific rigor of the evaluation model deteriorates

Engineering Contradiction:

Improveevaluation accessibilityVSAvoidcritical condition determination accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent replaces the subjective, human-based determination of critical conditions with objective experimental measurements. Pyrolysis experiments and fluid inclusion analysis provide quantifiable, reproducible data that automatically determine Roce and Rogen values, eliminating subjective bias while maintaining evaluation accessibility through standardized experimental protocols that can be universally applied.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11499957B1Evaluation method for residual hydrocarbon of post- to over-mature marine source rocks

Publication Date: 2022.11.15 INSTITUTE OF GEOLOGY AND GEOPHYSICS CHINESE ACADEMY OF SCIENCES

AI summary

An evaluation method for residual hydrocarbon of post- to over-mature marine source rocks includes the following steps: establishing a hydrocarbon generation potential evolution profile and a hydrogen index evolution profile of post- to over-mature source rocks; determining a critical condition for hydrocarbon expulsion of the source rocks, and inverting original hydrocarbon generation potential of the source rocks; inverting a critical condition for hydrocarbon generation of the source rocks; establishing a hydrocarbon generation, expulsion and retention model for the source rocks; determining a hydrocarbon generation rate, a hydrocarbon expulsion rate and a hydrocarbon retention rate of the source rocks; and calculating a hydrocarbon retention intensity and residual hydrocarbon of the source rocks. The evaluation method establishes an evaluation model for residual hydrocarbon of post- to over-mature source rocks without relying on immature to sub-mature samples.