Pump-Down Sensor Buoyancy Control for Downhole Monitoring
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Solution Overview
Problem
Conventional downhole sensors in the oil and gas field face limitations in real-time monitoring during processes like fracking due to interference and require larger borehole clearances, while optical fiber cables offer limited parameter monitoring capabilities, necessitating alternative sensing systems that can measure multiple parameters and communicate in real time with minimal borehole size.
Innovation Solution
Pump-down sensor devices using distributed or quasi-distributed fiber-optic sensing systems that deploy untethered sensor devices through a pipe, converting measured parameters into acoustic signals transmitted via optical fibers, with flow baffles for buoyancy control, allowing deployment on demand and retrieval without increasing borehole diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional downhole sensors are permanently installed on casing or tubing, then real-time monitoring capability is improved, but the required borehole clearance increases
Solution Approach 1:
The sensor device is deployed inside a delivery catheter that is pumped through the borehole. The sensor device nests within the catheter during deployment, allowing the entire assembly to pass through smaller clearances than a self-contained sensor of equivalent functionality would require.
Solution Approach 2:
The patent replaces traditional mechanical sensor mounting systems (attached to casing or tubing) with a fluid-driven delivery system. The sensor device is carried by pumping fluid through the catheter, eliminating the need for mechanical attachment structures that would increase clearance requirements.
2Measurement precision
If wireline logging is used for downhole measurements, then measurement capability is improved, but interference with completion and stimulation processes occurs
Solution Approach 1:
The sensor device is deployed and retrieved using the existing pumping infrastructure already in place for completion and stimulation operations. The same pumps used to inject fracturing fluid or cement are utilized to deploy and retrieve the sensor, eliminating the need for separate wireline operations that would interfere with these processes.
Solution Approach 2:
The patent uses hydraulic pumping to deploy and retrieve the sensor device through the borehole. This allows measurements to be taken during fluid injection operations without requiring separate wireline logging trips, enabling simultaneous operation with completion and stimulation processes.
3Area of stationary object
If optical fiber cables are used for sensing, then borehole size is reduced, but the number and types of measurable parameters are limited
Solution Approach 1:
The sensor device incorporates multiple sensor types (acoustic, temperature, pressure, vibration) within a single compact unit. This multi-functional sensor can measure various downhole parameters simultaneously, overcoming the limitation of optical fiber's single-parameter sensing capability while maintaining compatibility with the reduced borehole size enabled by optical fiber deployment.
Solution Approach 2:
The patent combines multiple sensing capabilities (acoustic sensors, temperature sensors, pressure sensors, vibration sensors) into a single integrated sensor device. This merged sensor package provides comprehensive downhole parameter measurement while maintaining the small form factor required for optical fiber-based deployment.
4Ease of operation
If sensor devices are pumped downhole through pipe, then deployment flexibility is improved, but buoyancy control becomes necessary
Solution Approach 1:
The sensor device incorporates buoyancy control by adjusting the density of the device relative to the pumping fluid. This is achieved by using materials with specific densities or by incorporating adjustable buoyancy elements, allowing the device to be neutrally buoyant during pumping operations and then return to the surface when pumping stops.
Solution Approach 2:
The patent uses buoyant materials (such as foam or air-filled chambers) to counterbalance the weight of the sensor device. This anti-weight mechanism allows the device to be easily pumped downhole with minimal pumping force and then naturally return to the surface when the pumping force is removed, simplifying both deployment and retrieval operations.
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
Enables real-time downhole measurement and communication of multiple parameters with minimal borehole size, facilitating continuous monitoring and efficient deployment and retrieval of sensor devices, thereby enhancing operational efficiency and reducing drilling costs.
Implementation Method 1
an electro-acoustic transmitter (e.g., a piezoelectric transducer) that converts an electronic signal encoding the measured parameter(s) into an acoustic signal encoding the measured parameter(s)
Implementation Method 2
The acoustic signal is transmitted to and picked up by an optical fiber that can be interrogated from the surface
Implementation Method 3
one or more flow baffles, e.g., made of syntactic foam, that are configured for a specified buoyancy of the sensor device relative to its weight
Data Source
AI summary
Disclosed are pump-down sensor devices that operate in conjunction with a fiber-optic sensing system to take downhole measurements and communicate them to the surface while moving untethered through a borehole. A pump-down sensor device in accordance with various embodiments includes one or more flow baffles configured for a specified buoyancy, and an electronics module for measuring one or more downhole parameters and transmitting an acoustic signal encoding the measured parameter(s). The acoustic signal can be detected using the fiber-optic sensing system. Additional embodiments are disclosed.