Solid Acoustic Couplers for Downhole Logging
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Solution Overview
Problem
Drilling in underbalanced conditions with high gas presence in the wellbore leads to significant attenuation of acoustic signals, resulting in missing or noisy data that hampers accurate determination of rock properties and directional adjustments during hydrocarbon drilling.
Innovation Solution
The use of solid acoustic couplers that reduce signal attenuation by transmitting soundwaves through a gas-filled annulus, allowing for more effective acoustic coupling between the drill string and the geologic formation, thereby improving the signal-to-noise ratio and enabling real-time geo-steering adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drilling is performed in underbalanced conditions with high gas presence, then drilling efficiency and wellbore stability are improved, but acoustic signal attenuation increases significantly
Solution Approach 1:
The patent introduces solid acoustic couplers as intermediary elements between the acoustic sources/receivers and the formation. These couplers physically contact the formation through the gas-filled annulus, serving as a mediator that transfers acoustic energy more efficiently than gas alone, thereby reducing signal attenuation while maintaining underbalanced drilling conditions
Solution Approach 2:
The patent changes the physical state and properties of the coupling medium by using solid couplers instead of relying on gas transmission. This parameter change from gas-phase to solid-phase coupling fundamentally alters the acoustic transmission characteristics, reducing attenuation without changing the underbalanced drilling regime
2Measurement precision
If solid acoustic couplers are used to reduce signal attenuation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The solid acoustic couplers serve multiple functions simultaneously: they provide acoustic coupling to reduce attenuation, they maintain drill string centralization in the wellbore, and they enable mechanical contact with the formation. This multi-functionality reduces the need for separate devices, thereby limiting the increase in overall system complexity while achieving improved measurement precision
3Adaptability or versatility
If acoustic signals are transmitted through gas-filled annulus, then drilling operations can proceed in underbalanced conditions, but signal-to-noise ratio deteriorates
Solution Approach 1:
The solid acoustic couplers act as intermediaries that bridge the gap between the acoustic sources/receivers and the formation through the gas-filled annulus. They provide a preferred acoustic pathway with lower attenuation, enabling clear signal transmission while maintaining the adaptability to drill in underbalanced conditions with gas presence
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 solution enhances the accuracy of rock property determination and drilling direction adjustments by reducing signal attenuation, allowing for more precise targeting of hydrocarbon-bearing layers even in underbalanced conditions with high gas presence.
Implementation Method 1
Reflected soundwaves are carried from the geologic formation to the set of solid acoustic couplers at least in part through the portions of the gas released into the wellbore during the drilling. The reflected soundwaves transmitted by the set of solid acoustic couplers are less attenuated compared to the reflected soundwaves transmitted through the portions of the gas
Data Source
AI summary
A deviated or horizontal wellbore is drilled in a geologic formation with a multiphase fluid including a gas by a rotating drill bit positioned at a downhole end of a drill string. Portions of the gas are released into the wellbore during the drilling. During the drilling, soundwaves are emitted into the geologic formation from within the wellbore by a set of acoustic emitters attached to the drill string. The received reflected soundwaves are transmitted by the set of solid acoustic couplers to a set of acoustic sensors contacting the solid acoustic couplers. The reflected soundwaves are received by the acoustic sensors. Rock properties of the geologic formation are determined based on the less attenuated reflected soundwaves transmitted to the acoustic sensors by the solid acoustic couplers. A drilling direction of the wellbore is adjusted based on the determined rock properties.