Fiber Optic Wellbore Sensing for Frac Height and Integrity
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Solution Overview
Problem
Current methods for monitoring and optimizing hydraulic fracture processes in unconventional wells are inefficient and costly, relying on trial-and-error approaches and inaccurate surface measurements, lacking direct data on in-situ hydraulic fracture dimensions and fluid movement, which limits the understanding of production requirements and reservoir behavior.
Innovation Solution
A system comprising downhole tools with extendable arms and sensors, including conductivity, strain, and pressure sensors, deployed in both vertical and horizontal sections of the well to collect real-time data on frac height, fluid movement, and casing strain, enabling accurate monitoring and optimization of hydraulic fracture processes without requiring significant changes to existing procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If surface measurements and simulations are used to determine downhole parameters, then the complexity of downhole equipment is reduced, but the measurement precision and accuracy of frac height and fluid movement data deteriorate
Solution Approach 1:
The patent replaces traditional mechanical cable-based pressure and temperature sensors with fiber optic sensing technology. This substitution eliminates the need for physical cables running through the wellbore, reducing mechanical complexity while enabling distributed sensing along the entire length of the well. The fiber optic system provides accurate measurements of frac height, fluid movement, and formation deformation without the limitations of cable-based systems.
Solution Approach 2:
The patent transitions from point-based measurements at the surface or at discrete depths to continuous distributed measurements along the entire wellbore length. By using distributed fiber optic sensing, the system captures data across multiple dimensions (spatial distribution along the well), enabling precise determination of frac height and fluid movement that cannot be achieved with traditional surface measurements or discrete downhole gauges.
2Loss of information
If cable-based pressure and temperature sensors are deployed outside the casing, then some downhole information can be obtained, but the reliability deteriorates due to risk of cable perforation and failure
Solution Approach 1:
The patent replaces vulnerable electrical cables with fiber optic sensing technology. Fiber optic cables are immune to electrical interference, corrosion, and mechanical damage that plagues traditional cable-based systems. The distributed sensing capability along the entire fiber length provides continuous monitoring without requiring physical connections or power supply to individual sensor points, eliminating failure modes associated with cable perforation and electrical connections.
3Productivity
If the number of clusters and horizontal section length are increased to improve production, then productivity increases, but the cost and inefficiency worsen due to trial-and-error approaches
Solution Approach 1:
The patent implements real-time feedback through distributed fiber optic sensing that continuously monitors pressure, temperature, and strain during the fracturing process and production phase. This feedback enables operators to observe actual frac height, fluid movement patterns, and formation response, allowing for optimization of clustering density and horizontal section length based on measured performance rather than trial-and-error approaches. The system provides the data needed to determine the optimal balance between productivity and cost efficiency.
4Loss of information
If tiltmeters and microseismic monitoring are used to obtain fracture data, then some fracture process information is obtained, but the measurement precision of formation deformation deteriorates due to surface location limitations
Solution Approach 1:
The patent moves the sensing capability from the surface dimension to the subsurface dimension by deploying fiber optic sensing along the entire wellbore length. This dimensional shift places sensors in direct contact with the formation environment, enabling precise measurement of formation deformation, frac height, and fluid movement at the actual location of interest rather than inferring these parameters from surface measurements. The distributed nature of the sensing provides spatial resolution that neither surface tiltmeters nor microseismic monitoring can achieve.
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
The system provides accurate, real-time data for frac evaluation, optimizing hydraulic fracture stimulation and increasing hydrocarbon production efficiency, reducing costs and extending well life by enabling better understanding and control of frac processes and fluid movement.
Implementation Method 1
strain sensors mounted on a second predetermined subset of the set of extendable arms 11
Implementation Method 2
pressure sensors (which can be disposed inside and/or outside of tools 40,50)
Implementation Method 3
at least one sensor 20 comprising a conductivity sensor configured to collect resistivity data from reservoir 111
Implementation Method 4
where a fiber optic string is used instead of an electrical cable. The fiber optic can be used to determine distributed temperature and distributed strain (sound) downhole
Data Source
AI summary
A system for deploying sensors throughout a vertical section and a horizontal section of an unconventional well comprises a mandrel comprising a set of extendable arms; a conductivity sensor mounted on a first predetermined subset of the set of movable arms; a strain sensor mounted on a second predetermined subset of the set of movable arms; a first downhole tool configured to be placed in the horizontal section of the unconventional well; a second downhole tool placed in a vertical section of the well, the first downhole tool and the second downhole tool adapted to operate simultaneously; a navigation package; a real time communications short hop data communicator; a data communicator; a downhole power source; and a surface system configured to collect and process data obtained in the well. The system can be used to provide data to evaluate conditions in the well and its reservoirs as well as frac height and frac width.