Shale Fluid Production Model Using Acoustic Wave Dynamics
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Solution Overview
Problem
Conventional models based on Darcy's law fail to explain the rapid production of oil and gas from shale reservoirs, as they predict impractically long times for fluid migration due to low permeability and high viscosity, contradicting the observed booming shale production.
Innovation Solution
A method and system that estimate and control fluid production from shale reservoirs by modeling drainage rates proportional to fluid viscosity and independent of pore radius and permeability, using a damped acoustic wave model for fluid drainage, which deviates from traditional fluid dynamics theories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Darcy's law models are used to estimate fluid production from shale reservoirs, then the models predict extremely long migration times (over 70 years for one meter), but this contradicts the observed rapid shale production boom where large quantities are produced within one year
Solution Approach 1:
The patent changes the fundamental parameters of the flow model by introducing a power-law relationship where flow rate is proportional to the nth power of the pressure gradient (with n > 1), rather than the linear relationship in Darcy's law. This parameter change allows the model to capture the non-Darcian flow behavior in ultra-tight shale formations, enabling finite and practical migration times while maintaining model reliability against observed production data
Solution Approach 2:
The patent replaces the conventional Darcy's law mechanical flow model with a new theoretical framework that incorporates power-law flow behavior and acoustic wave phenomena. This substitution introduces a fundamentally different mechanical description of fluid movement through nano-pores, replacing the diffusive Darcy model with a wave-based model that predicts finite propagation speeds consistent with observed rapid production
2Productivity
If Darcy's law is applied to ultra-tight shale matrix with permeability as low as one nano-darcy, then the predicted fluid migration speed becomes infinitesimally small, but actual shale reservoirs demonstrate high production rates
Solution Approach 1:
The patent modifies the flow velocity parameter relationship by introducing a power-law exponent n > 1, which changes how pressure gradient translates to flow velocity. In ultra-tight shale, this parameter change allows the model to predict finite migration speeds that are many orders of magnitude faster than Darcy's law, while still being constrained by the low permeability, thus reconciling high productivity with low permeability conditions
Solution Approach 2:
The patent incorporates acoustic wave phenomena that introduce periodic oscillatory behavior to the fluid flow process. These pressure waves create periodic acceleration and deceleration of fluid movement, enabling finite average migration speeds through the nano-pore network that are consistent with observed rapid production rates, rather than the infinitesimally slow continuous diffusion predicted by Darcy's law
3Productivity
If conventional porous media flow theory is used, then the model cannot explain oil production from shale due to high shear viscosity, but the patent demonstrates that oil can be produced efficiently from shale reservoirs
Solution Approach 1:
The patent changes the viscosity dependency parameter in the flow model, making the flow rate directly proportional to viscosity rather than inversely proportional. This parameter inversion, combined with the power-law pressure gradient relationship, allows the model to predict that higher viscosity oils can be produced at practical rates from shale, contrary to conventional wisdom that low permeability combined with high viscosity makes production impossible
Solution Approach 2:
The patent replaces the conventional viscous flow model with an acoustic wave-based model that fundamentally changes how viscosity affects flow. In this new mechanical framework, viscosity becomes a damping parameter for acoustic waves rather than a resistive force, allowing viscous oils to be produced through wave-driven mechanisms that overcome the limitations of conventional porous media flow theory
Data Source
AI summary
Disclosed are methods and systems for modeling and controlling production of an oil and/or gas, for example from a shale reservoir. The modeling includes receiving data associated with a fluid reservoir, including a viscosity of a fluid in the reservoir and a radius of a pore in the reservoir, and not including a permeability of the reservoir. The resulting model includes a reservoir fluid drainage rate that is proportional to the fluid viscosity and a reservoir fluid drainage speed that is independent of the pore radius. The model may be used to control a pump which pumps a fluid into and/or out of the reservoir.