Dual-Continuum Shale Gas Flow Analysis via Pulse-Decay
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Solution Overview
Problem
Current methods for characterizing and modeling shale gas flow in subterranean reservoirs, particularly in tight formations, face limitations in accurately identifying and analyzing dual-continuum flow behaviors, which are crucial for enhancing natural gas recovery.
Innovation Solution
A method involving pulse-decay and dual-continuum test systems to determine mass transfer coefficients by creating pressure pulses across a reservoir sample, isolating it, and measuring pressure data to characterize flow characteristics, specifically addressing dual-continuum flow in shale formations with both fast and slow pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulse-decay methods are used for characterizing shale gas flow, then basic permeability measurements can be obtained, but accurate identification and analysis of dual-continuum flow behaviors cannot be achieved
Solution Approach 1:
The patent divides the reservoir into two distinct continua (matrix and fracture systems) and develops separate flow equations for each, allowing independent characterization of fast and slow flow pathways. This segmentation enables accurate dual-continuum flow analysis by treating each continuum with appropriate boundary conditions and flow regimes.
Solution Approach 2:
The patent introduces an intermediary mass transfer coefficient that couples the matrix and fracture continua, representing the mass exchange between the two systems. This intermediary parameter enables the connection between separate continuum models while maintaining measurement feasibility through standard pulse-decay apparatus.
2Reliability
If traditional single-continuum models are applied to shale reservoirs, then simplified analysis can be performed, but accurate prediction of production capabilities in tight formations with dual-continuum flow is compromised
Solution Approach 1:
The patent develops dynamic flow equations that account for time-dependent mass transfer between matrix and fracture continua. The model captures transient flow behavior during pressure depletion, allowing accurate prediction of production rates at different time stages while adapting to changing flow conditions in tight shale formations.
Solution Approach 2:
The patent introduces key parameters including matrix permeability, fracture permeability, and mass transfer coefficient that can be determined from pulse-decay tests. These parameters enable quantitative characterization of dual-continuum flow properties and improve production prediction reliability by capturing the essential physics of tight reservoir behavior.
3Measurement precision
If conventional permeability measurement methods are used, then basic flow properties can be determined, but mass transfer coefficients for dual-continuum flow cannot be accurately estimated
Solution Approach 1:
The patent performs preliminary pressure equalization of the matrix and fracture continua before initiating the pulse-decay test. This preliminary action ensures that the initial conditions are well-defined and that subsequent pressure changes can be accurately attributed to mass transfer between continua, facilitating precise coefficient determination.
Solution Approach 2:
The patent uses real-time pressure monitoring during the pulse-decay test to detect the characteristic dual-phase pressure response. By analyzing the feedback from pressure measurements at multiple locations and times, the model can iteratively determine mass transfer coefficients that best match the observed pressure behavior, enabling accurate parameter estimation.
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 approach allows for the accurate estimation of mass transfer coefficients and improved characterization of shale gas flow, enhancing the prediction of production capabilities and recovery efficiency in subterranean reservoirs.
Implementation Method 1
creating a plurality of pressure pulses across the reservoir sample
Implementation Method 2
determining a mass transfer coefficient from the dual-continuum test data
Data Source
AI summary
The present invention relates to methods for analyzing and modeling natural gas flow in subterranean shale reservoirs. In preferred 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 herein may be used in various reservoirs exhibiting macroporosity and/or microporosity, such as fractured reservoirs and carbonate reservoirs composed of reservoir fluids.