Multi-Sensor Workflow for Gas Flow Evaluation in Casing Strings
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Solution Overview
Problem
Current methods for evaluating cement bonding in wellbores with multiple casing strings lack integration of sensor measurements, failing to effectively identify and characterize fluid flow paths between casings and the wellbore wall, particularly in deep water applications, where the absence of cement or a defective bond can lead to fluid migration and contamination of hydrocarbon zones.
Innovation Solution
An integrated workflow method utilizing pulsed neutron, noise, Doppler, and temperature sensors to create semi-descriptive borehole models that predict the location, velocity, and radial distance of gas flow paths between concentric casing strings, without requiring new tool hardware, by analyzing data from these sensors and correlating their measurements to determine the presence and characteristics of gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sonic tools or ultrasonic tools are used to evaluate cement bonding, then cement bond evaluation is possible, but the ability to effectively identify and characterize fluid flow paths in multiple casing strings is insufficient
Solution Approach 1:
The patent combines multiple sensor systems (acoustic sensors, temperature sensors, flow sensors, and sonic/ultrasonic sensors) into a single integrated tool string. This merging allows the system to simultaneously perform cement bond evaluation and fluid flow path characterization in multiple casing strings, resolving the contradiction between measurement precision for cement bonding and adaptability for flow path identification.
Solution Approach 2:
The integrated sensor system is designed to perform multiple functions: evaluating cement bonding between casing strings and formation, identifying fluid flow paths, characterizing flow rates, and detecting leaks or channels. This multi-functional approach enables the same tool to address both cement bond evaluation and fluid flow characterization, particularly in complex multi-casing configurations.
2Device complexity
If only one system of sensors is used to infer fluid flow parameters, then the evaluation method is simple, but the characterization of subsequent interfaces in multiple casing strings is precluded
Solution Approach 1:
The patent merges multiple sensor systems (acoustic, temperature, flow, and sonic/ultrasonic sensors) into a single integrated tool string. This combination enables the system to characterize multiple cement-casing interfaces in multi-casing strings simultaneously, overcoming the limitation of single-sensor systems while maintaining manageable complexity through integrated data processing.
Solution Approach 2:
The patent introduces an integrated data processing system that acts as an intermediary, correlating measurements from multiple sensor types to characterize fluid flow paths and cement bonds at multiple interfaces. This intermediary processing layer enables multi-interface characterization by synthesizing data from the sensor array, effectively translating complex multi-sensor inputs into comprehensive flow path identification.
3Measurement precision
If current methods are used for the characterization of the first casing-cement bond, then the first interface is evaluated, but subsequent interfaces in multiple casing strings cannot be evaluated
Solution Approach 1:
The integrated sensor system is designed with universal applicability to evaluate any casing-cement interface, whether it is the first interface or subsequent interfaces in multi-casing strings. The system can characterize cement bonds and fluid flow paths at multiple depths and interfaces by moving the tool string to different positions, providing versatile evaluation capability across all interfaces.
Solution Approach 2:
The patent employs a dynamic evaluation approach where the tool string can be moved to different depths and positions within the wellbore to evaluate multiple interfaces. The system dynamically adapts its measurement and characterization capabilities to assess each specific interface (first casing-cement bond, subsequent interfaces) according to its unique conditions, enabling comprehensive multi-interface evaluation.
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 allows for accurate characterization of gas flow paths and cement interfaces, enabling precise identification of gas presence and flow rates between casing strings, thereby preventing fluid migration and ensuring the integrity of hydrocarbon production zones.
Implementation Method 1
obtain data from a pulsed neutron sensor, a noise sensor, a Doppler sensor, and a temperature sensor
Implementation Method 2
calculate a second distance of the flow path from the tool string and a first velocity of a gas flow in the flow path using a noise log borehole model and the data obtained from the noise sensor
Implementation Method 3
operate the Doppler sensor to obtain Doppler log (DL) data from the wellbore, calculate a third distance of the flow path from the tool string and a second velocity of the gas flow in the flow path using a Doppler borehole model and the DL data
Implementation Method 4
calculate a fourth distance of the flow path from the tool string and a third velocity of the gas flow in the flow path using a temperature borehole model and the data obtained from the temperature sensor
Data Source
AI summary
A distance of a gas flow path and a velocity of the gas flow therein are calculated using pulsed neutron data and noise data. The gas saturation and distance to flow path obtained from the pulsed neutron data and gas velocity and distance to flow path obtained from the noise data are compared with each other to obtain a first calculated distance and a first calculated velocity. The distance and the velocity of the gas flow are calculated using Doppler data. The distance and velocity values are compared with the first calculated distance and first calculated velocity to obtain a second calculated distance and velocity values. The distance and the velocity of the gas flow are calculated using temperature data. The distance and velocity values are compared with the second calculated distance and velocity to determine a distance of a cement interface and a velocity of a gas flow therein.