Downhole Sensor Nesting in SAGD Production Tubing
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Solution Overview
Problem
In steam assisted gravity drainage (SAGD) systems, existing methods for measuring downhole parameters are prone to damage and require frequent work-over procedures, leading to increased costs and time due to externally connected sensors on the short production tubing string, which are often damaged during maintenance and replacement.
Innovation Solution
Positioning downhole sensors within the long production tubing string allows for the detection and transmission of downhole parameters without the need to pull sensory apparatus to the surface during work-over procedures, reducing the frequency and cost of replacing sensors, optical fibers, and external connectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If downhole sensors are externally connected to the short production tubing string, then downhole parameters can be detected, but the sensors are prone to damage and require frequent work-over procedures
Solution Approach 1:
The sensor system is nested within the long production tubing string, which itself is positioned within the production well. This nested arrangement protects the sensors from external damage during work-over procedures while maintaining their ability to detect downhole parameters. The long tubing string acts as a protective container for the sensing apparatus.
Solution Approach 2:
The sensors are extracted from the short production tubing string and relocated to the long production tubing string. This extraction removes the sensors from the problematic environment where they were previously vulnerable to damage during work-over procedures, thereby improving their reliability and reducing maintenance frequency.
2Measurement precision
If sensors are positioned on the short production tubing string, then downhole parameters can be measured, but replacement costs and work-over times increase
Solution Approach 1:
The sensor system is nested within the long production tubing string structure, allowing continuous downhole parameter measurement while protecting the sensors from damage. This nested configuration eliminates the need to retrieve sensors during routine work-over procedures, significantly reducing work-over time while maintaining measurement capabilities.
3Loss of information
If externally connected sensors are used on the short production tubing string, then downhole monitoring is achieved, but sensor and connector damage occurs frequently
Solution Approach 1:
The sensors are nested within the long production tubing string, which provides physical protection against harmful factors such as mechanical damage, thermal stress, and chemical exposure. This nested configuration maintains downhole parameter monitoring while shielding the sensors from damaging environmental conditions.
Solution Approach 2:
The sensors are extracted from the vulnerable external position on the short tubing string and relocated to the protected environment within the long tubing string. This extraction removes them from harmful external factors while preserving their monitoring function.
Data Source
AI summary
The present invention provides a system and method for measuring downhole parameters within a SAGD system. The system includes one or more downhole sensors that are positioned at least within a heel portion of a long production tubing string. Positioning the system within the long production tubing string avoids pulling the sensors to surface each time that the short production tubing string is worked over. The system comprises a ported sub that is threadably connected as part of the long production tubing string. When the tubing string is in a desired position, the ported sub is near the heel portion of the production well. The system further comprises a pumpable sleeve that carries the instrument line downhole into the ported sub. When the pumpable sleeve lands in the ported sub, the instrument line detects information regarding downhole parameters at the heel portion of the production well.