Wellbore Plug Position Tracking Using Pressure Pulse Reflections
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Solution Overview
Problem
Existing cementing operations face challenges in accurately monitoring the positions of wiper plugs and drillpipe darts within a casing string due to uncertainties such as borehole rugosity, pump rate fluctuations, and deviations from nominal casing geometry, leading to difficulties in achieving uniform cement sheath placement and real-time monitoring.
Innovation Solution
The method involves generating pressure pulses as cementing plugs pass through casing joints with positive upsets, recording these pulses with a pressure transducer, and processing the data using cepstral analysis to determine the position of the plugs in real-time by calculating reflection times and velocities, utilizing a casing tally for depth correlation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional cementing operations are performed without real-time monitoring, then the operation can proceed with standard equipment and procedures, but the position of wiper plugs and drillpipe darts cannot be accurately determined, leading to uncertainties in cement sheath placement
Solution Approach 1:
The patent replaces complex mechanical monitoring systems with a pressure-based detection system. Pressure pulses are generated and detected to determine plug positions, substituting mechanical measurement methods with a simpler pressure sensing approach that provides accurate real-time positioning without requiring complex device assemblies
Solution Approach 2:
The patent introduces pressure pulses as an intermediary medium to transmit information about plug positions. These pressure waves serve as a mediator between the plugs/darts and the detection system, enabling indirect but accurate measurement of object positions through pressure wave propagation and reflection characteristics
2Reliability
If real-time monitoring of plug positions is implemented, then accurate positioning and informed operational decisions can be made, but additional equipment and data processing requirements increase system complexity
Solution Approach 1:
The patent implements a feedback mechanism where pressure pulse responses are continuously monitored and processed to provide real-time information about plug positions. This feedback loop enables operators to make informed decisions during cementing operations, improving reliability by allowing dynamic adjustments based on actual plug locations rather than relying on pre-calculated positions
Solution Approach 2:
The patent replaces complex mechanical positioning systems with pressure wave-based detection. By using pressure pulses and their reflection characteristics, the system achieves reliable position determination through simpler sensing equipment and data processing compared to traditional mechanical measurement systems
3Difficulty of detecting and measuring
If standard casing joints are used without positive upsets, then the casing string can be assembled with conventional components, but pressure pulses cannot be generated when plugs pass through, preventing position detection
Solution Approach 1:
The patent applies local quality by introducing positive upsets at specific locations within the casing joints rather than modifying the entire casing string. These localized geometric features are strategically placed to generate pressure pulses when plugs pass through, providing detectable signals without requiring comprehensive modification of all casing components
Solution Approach 2:
The patent modifies the geometric parameters of casing joints by introducing positive upsets - small dimensional changes in the joint geometry that create pressure pulse generation points. These parameter changes are minimal and localized, maintaining ease of manufacture while fundamentally enabling the pressure-based detection functionality
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 monitoring and accurate positioning of cementing plugs, allowing operators to make informed decisions on displacement progress and cement sheath uniformity during cementing operations.
Implementation Method 1
A droppable object is placed inside the casing string, and a fluid is pumped behind the droppable object, causing the droppable object to travel through the interior of the casing string and pass through the at least one casing joint that comprises at least two positive upsets having a size of at least 3 mm, but smaller than that which would prevent passage of the droppable object through the inside of the casing string, thereby generating a pressure pulse.
Implementation Method 2
The pressure data are recorded by a pressure transducer, and transmitted to the pressure data acquisition system.
Data Source
AI summary
The position of a droppable object (e.g., a cementing plug or drillpipe dart) in a cased wellbore may be determined in real time during a cementing operation. A pressure data acquisition system is installed at a wellsite and a pressure transducer is installed at the wellhead. As the droppable object travels through casing it encounters regions with a positive or a negative change of inner cross-sectional dimension. The droppable object generates a pressure pulse as it passes through the regions. The pressure pulse and associated reflections are detected by the pressure transducer, and the signals are processed mathematically to determine the position of the droppable object. Special casing joints may be installed that comprise positive dimensional upsets that have a size of at least 3 mm. Such upsets may ensure the generation of pressure pulses of sufficient magnitude for detection by the pressure transducer.