Downhole Fluid Detector Using Fluorescent Tracers
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Solution Overview
Problem
In secondary oil and gas well production, 'short circuits' between injection and production wells reduce hydrocarbon displacement efficiency due to preferential flow paths, leading to reduced recovery and revenue, as existing analysis techniques struggle with distinguishing between multiple flow paths and identifying the source and path of communication.
Innovation Solution
A method and apparatus using a downhole fluid detector with visible and ultraviolet light sources and an optical receiver to capture images of fluid flows in a wellbore, distinguishing between hydrocarbon fluids and tracer fluids, allowing for quantification and identification of communication paths, and enabling remedial actions to correct short circuits without damaging hydrocarbon-producing intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If production logging techniques are used to identify short circuits, then fluid flow paths can be inferred, but the ability to precisely distinguish between multiple flow paths and identify their sources is limited
Solution Approach 1:
The patent applies fluorescent tracers that emit different colors under ultraviolet illumination to distinguish between injected fluids and formation fluids. This allows visual differentiation of multiple flow paths and their sources, directly resolving the limitation of conventional production logging in identifying specific fluid origins and path characteristics.
2Ease of operation
If multiple flow paths exist between injection and production wells, then fluid communication is established, but analysis becomes confused and difficult to interpret
Solution Approach 1:
By assigning different fluorescent tracers with distinct emission characteristics to different injection wells or flow paths, the system enables clear visual and quantitative differentiation of multiple simultaneous flow paths. This eliminates the confusion in analysis by providing distinct spectral or color signatures for each path.
Solution Approach 2:
Fluorescent tracers act as intermediaries that are introduced with injected fluids to mark and trace their paths. These tracers provide a detectable signal that facilitates the identification and analysis of flow paths without interfering with the actual fluid flow or reservoir processes.
3Productivity
If injected fluids flow quickly through short circuits, then fluid communication is established, but hydrocarbon displacement efficiency is reduced
Solution Approach 1:
The system enables preliminary identification of short circuits through fluorescent tracer detection before significant displacement efficiency loss occurs. By detecting the presence and concentration of tracers in produced fluids, operators can identify preferential flow paths early and take corrective actions such as well isolation or injection pattern modification to prevent extensive energy waste.
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 solution effectively identifies and corrects short circuits, preventing extensive cycling of injected fluids, reducing revenue loss, and enhancing hydrocarbon recovery by accurately differentiating between hydrocarbons and injected fluids, thereby improving production profile analysis and profile control in mature zones.
Implementation Method 1
generating light in a visible spectrum from a light source in a production wellbore; generating light in an ultraviolet spectrum from the light source in the production wellbore
Implementation Method 2
capturing at least one image of a combined flow of the first fluid and the second fluid in at least one of the visible spectrum and the ultraviolet spectrum with an optical receiver in the production wellbore
Data Source
AI summary
In one general implementation, a method for identifying fluids in a wellbore includes generating light in a visible spectrum from a light source in a production wellbore; generating light in an ultraviolet spectrum from the light source in the production wellbore; receiving a first fluid in the production wellbore from a subterranean zone; receiving a second fluid in the production wellbore from the subterranean zone; capturing at least one image of a combined flow of the first fluid and the second fluid in at least one of the visible spectrum and the ultraviolet spectrum with an optical receiver in the production wellbore; and distinguishing, at least in part through the image, the first fluid from the second fluid in either or both the visible and ultraviolet spectrums.