Pulse-Decay Shale Gas Flow Analysis for Dual-Continuum Reservoirs

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Solution Overview

Problem

Existing methods for characterizing and modeling shale gas flow in subterranean reservoirs, particularly in tight shale formations, are limited by their inability to accurately account for dual-continuum behavior and require the same volume of upstream and downstream reservoirs, leading to inefficiencies in experimental time and accuracy.

Innovation Solution

A new approach is introduced to estimate the mass transfer coefficient using pulse-decay permeability (PDP) measurements with different volumes of upstream and downstream reservoirs, allowing for the characterization of dual-continuum behavior and improved determination of gas flow properties in shale formations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the same volume of upstream and downstream reservoirs is used in PDP measurements, then the mass transfer coefficient can be determined using existing methods, but the experimental time is increased

Engineering Contradiction:

Improvemass transfer coefficient determinationVSAvoidexperimental time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies asymmetry by allowing different volumes for the upstream and downstream reservoirs in the PDP measurement system. This breaks the traditional symmetry constraint (Vu = Vd) and enables more flexible experimental configurations that reduce experimental time while maintaining accurate mass transfer coefficient determination through the modified analytical method

Inventive Principle:

Principle #4Asymmetry

2Measurement precision

If existing PDP measurement methods are used, then permeability characterization is achieved, but dual-continuum behavior cannot be accurately characterized

Engineering Contradiction:

Improvepermeability characterizationVSAvoiddual-continuum behavior characterization

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies segmentation by dividing the reservoir system into two distinct continua (matrix continuum and fracture continuum) with separate properties and flow behaviors. This segmentation enables the dual-continuum model to accurately characterize complex reservoir systems where both matrix permeability and fracture permeability play significant roles, going beyond single-continuum limitations

Inventive Principle:

Principle #1Segmentation

3Device complexity

If traditional single-continuum models are used, then analysis is simplified, but accuracy in tight shale formations is reduced

Engineering Contradiction:

Improveanalysis complexityVSAvoidshale gas flow characterization

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies the composite materials principle by combining two continuum models (matrix and fracture) into a dual-continuum system. This composite approach integrates the characteristics of both low-permeability matrix regions and high-permeability fracture regions, providing a more accurate representation of tight shale formation behavior than either continuum model alone

Inventive Principle:

Principle #40Composite materials

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 enhances the accuracy and efficiency of shale gas recovery by enabling the estimation of mass transfer coefficients in dual-continuum systems, reducing experimental time and improving the characterization of gas flow in subterranean reservoirs.

Implementation Method 1

pressure transient data to characterize the dual-continuum behavior

Methodology Applied

Scientific EffectPressure transient: Pressure Gradient

Implementation Method 2

pulse-decay permeability (PDP) measurements for the characterization and modeling of subterranean shale gas flow

Methodology Applied

Scientific EffectPermeability: Permeation

Implementation Method 3

introduced the mass transfer coefficient between the two continua for the matrix

Methodology Applied

Scientific EffectMass transfer: Diffusion

Implementation Method 4

dual-continuum behavior of the source rock formation

Methodology Applied

Scientific EffectDual-continuum flow: Two-Phase Flow

Data Source

PatentUS12529638B2Systems and methods for analyzing natural gas flow in subterranean reservoirs

Publication Date: 2026.01.20 SAUDI ARABIAN OIL CO

AI summary

Systems and methods for analyzing and modeling natural gas flow in subterranean shale reservoirs. In some embodiments, methodologies and techniques for determining and modeling natural gas flow in shale formations using methodologies and techniques capable of determining natural gas properties related to dual-continuum flow, permeability, and pressure within a subterranean shale reservoir. In some embodiments, the natural gas properties are determined by subjecting a subterranean shale reservoir sample to pulse-decay analysis. In certain embodiments, the methodologies and techniques described may be used in various reservoirs exhibiting macroporosity and microporosity, such as fractured reservoirs and carbonate reservoirs composed of reservoir fluids.