Acoustic Permeability Estimation Through Mudcake Layers
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Solution Overview
Problem
The presence of impermeable substances like mudcake in boreholes hinders accurate permeability measurements of earth formations, as existing methods struggle to account for the separation between borehole fluid and the porous formation, leading to reduced accuracy in hydrocarbon exploration and production.
Innovation Solution
A method and apparatus that utilize acoustic waves in the borehole fluid to estimate permeability by measuring pressure attenuation over time, leveraging theoretical models to account for the presence of impermeable mediums like mudcake, and employing an acoustic source and sensor system to generate and detect these waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic waves are used to measure permeability in boreholes, then measurement capability is provided, but the presence of impermeable mudcake reduces measurement accuracy
Solution Approach 1:
The patent uses borehole fluid as an intermediary medium to transmit acoustic waves between the acoustic source/sensor and the earth formation. The fluid couples the acoustic energy through the mudcake layer, allowing the measurement of formation permeability despite the impermeable barrier. The fluid acts as a mediator that enables acoustic energy transmission where direct contact would be blocked by mudcake.
Solution Approach 2:
The patent replaces direct mechanical contact methods with acoustic wave propagation through fluid. Instead of requiring direct mechanical coupling between the measurement tool and the formation, acoustic waves travel through the borehole fluid, interact with the formation across the mudcake interface, and return information about formation properties without direct mechanical penetration through the impermeable layer.
2Reliability
If impermeable substances build up on borehole walls, then borehole stability is maintained, but permeability measurement accuracy deteriorates
Solution Approach 1:
The patent converts the harmful effect of mudcake (impermeable barrier blocking measurements) into a useful measurement mechanism. By analyzing how acoustic waves attenuate and propagate through the mudcake-fluid-formation system, the method can actually determine formation permeability properties. The mudcake layer becomes part of the measurement pathway rather than an obstacle, allowing permeability estimation through the complex interaction of acoustic waves with the layered structure.
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 precise estimation of earth formation permeability even in the presence of impermeable layers, enhancing the accuracy of hydrocarbon exploration and production by effectively modeling and measuring acoustic wave attenuation through the mudcake layer.
Implementation Method 1
generating at least one acoustic wave in a borehole fluid acoustically coupled to the earth formation
Implementation Method 2
measuring a pressure attenuation of the at least one acoustic wave over time in the borehole fluid using an acoustic sensor
Data Source
AI summary
The present disclosure relates to methods and apparatuses for evaluating a porous earth formation. The method may include: generating an acoustic wave in a borehole fluid (820); measuring an attenuation of the acoustic wave (830); and estimating a permeability of an earth formation acoustically coupled to the borehole fluid using the estimated attenuation and a theoretical attenuation (850). The method may also include estimating a theoretical attenuation for the borehole fluid (840) using acoustic properties of the borehole fluid. The apparatus for performing the method may include: an acoustic source, an acoustic sensor, and a processor configured to estimate the attenuation of an acoustic wave generated by the acoustic source.