Droppable Object Positioning via Pressure Spectrogram Analysis
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Solution Overview
Problem
Conventional methods for monitoring the position of cementing plugs and drillpipe darts during cementing operations are inaccurate due to borehole rugosity, pump rate fluctuations, and uncertainties in casing geometry, leading to challenges in real-time tracking and displacement volume calculations.
Innovation Solution
The method involves recording pressure and fluid flow rate data to generate a pressure spectrogram, which is converted into pulses to determine the correct depth of droppable objects like cementing plugs and drillpipe darts within the casing string, using a data acquisition system and pressure transducers to match these pulses with casing tally pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional volumetric methods are used to monitor droppable object position, then the monitoring system is simple, but the measurement precision is poor due to borehole rugosity, pump rate fluctuations, and casing geometry uncertainties
Solution Approach 1:
The patent replaces conventional volumetric calculation methods with acoustic wave-based detection. Pressure transducers detect acoustic waves generated by droppable objects, and signal processing algorithms determine object positions. This substitution of mechanical/volumetric methods with acoustic field methods resolves the contradiction by providing high measurement precision through wave detection while maintaining practical system complexity through surface-based sensors.
Solution Approach 2:
The patent introduces acoustic waves as an intermediary medium to detect droppable object positions. The acoustic waves propagate through the fluid in the casing, reflect off or are generated by the droppable objects, and are detected by pressure transducers. This intermediary acoustic field enables precise position measurement without direct mechanical contact or complex internal sensors, resolving the contradiction between precision and complexity.
2Productivity
If real-time monitoring of droppable objects is implemented, then the productivity of cementing operations is improved, but the device complexity increases due to additional sensors and data processing requirements
Solution Approach 1:
The patent employs droppable objects that generate their own acoustic signals as they move through the casing. The objects themselves serve as signal sources, eliminating the need for external active transmitters or complex interrogation systems. This self-service approach enables real-time monitoring that improves productivity while limiting device complexity, as the monitoring system only requires passive detection capabilities rather than active signaling infrastructure.
Solution Approach 2:
The patent implements real-time feedback by continuously monitoring acoustic wave patterns and updating droppable object position calculations as new data arrives. This feedback mechanism allows operators to make immediate decisions about cementing operations based on current object positions, improving productivity. The system processes signals in real-time rather than requiring complex post-processing, balancing the feedback capability with manageable device complexity.
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 approach enables real-time monitoring of droppable objects, allowing operators to make immediate decisions on displacement and fluid volumes, reducing errors associated with traditional volumetric methods and improving the accuracy of cement placement.
Implementation Method 1
A pressure pulse is generated as the droppable object passes through the region with the change in inner cross-sectional dimension. The pressure transducer detects the pressure pulse and transmits pressure data to the pressure data acquisition system.
Implementation Method 2
A pressure pulse is generated as the droppable object passes through the region with the change in inner cross-sectional dimension
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, a pressure transducer is installed at the wellhead and a flowmeter is placed to measure fluid displacement rate. The fluid displacement causes the droppable object to travel through the casing towards a target position. During displacement the pressure data and flow-rate data are transmitted to a pressure data acquisition system and a flowmeter, respectfully. The pressure and flow-rate data are processed mathematically to obtain pressure pulses, pulse reflections or both. The fluid flow rate data and pressure data are processed by generating a pressure spectrogram converted to pulses. The pulses are then matched with casing tally pulses, thus allowing correction of the droppable object depth.