Downhole Explosive State Assessment via Sensor Sub
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Solution Overview
Problem
Existing wellbore perforating technologies face performance and safety concerns due to time-temperature limitations of explosive perforating charges and detonating cords, leading to incomplete firing and potential safety hazards during retrieval.
Innovation Solution
A method that assesses the downhole state of explosives in a perforating gun using downhole measurements of pressure, acceleration, and temperature, predicting performance and determining whether the gun has undergone detonation, strong deflagration, or weak deflagration, allowing for informed operational decisions and safety responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explosive perforating charges and detonating cord are used in perforating guns, then effective perforation can be achieved, but incomplete firing may occur due to time-temperature limits causing degradation and instability
Solution Approach 1:
The patent applies preliminary action by measuring temperature and calculating thermal decomposition before firing the perforating gun. This allows assessment of explosive stability prior to detonation, enabling operators to determine whether the explosives have degraded beyond safe or effective thresholds, thus preventing incomplete firing due to pre-degradation.
Solution Approach 2:
The patent implements feedback by continuously monitoring downhole temperature and calculating thermal decomposition of explosives both before and after firing. This feedback mechanism provides real-time information on explosive state, allowing operators to assess firing completeness and make informed decisions about wellbore safety and subsequent operations.
2Length of moving object
If perforating guns are deployed deep into wellbores, then access to target formation is achieved, but temperature exposure increases causing explosive degradation
Solution Approach 1:
The system performs preliminary temperature measurement and thermal decomposition calculation before the perforating gun reaches the target depth. This allows assessment of cumulative temperature exposure during conveyance, enabling operators to determine if explosives have degraded to a point where firing would be ineffective or unsafe.
Solution Approach 2:
The system provides continuous temperature monitoring and thermal decomposition feedback during the conveyance and firing process. This enables real-time assessment of temperature-induced degradation, allowing operators to understand the relationship between depth, temperature exposure, and explosive stability.
3Productivity
If firing attempts are made on degraded explosives, then perforation may be attempted, but safety hazards arise from incomplete firing and partially-fired components
Solution Approach 1:
The patent applies preliminary action by calculating thermal decomposition before firing attempts. This allows operators to identify degraded explosives in advance and make informed decisions to abort firing attempts or implement special safety procedures, preventing the creation of unsafe partially-fired conditions.
Solution Approach 2:
The system provides feedback on explosive degradation state both before and after firing. By measuring temperature and calculating thermal decomposition, the system enables operators to assess whether a firing attempt was complete or partial, and to implement appropriate safety responses during retrieval operations.
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 method mitigates safety issues by assessing the state of explosives before and after firing, ensuring effective perforation and safe retrieval by identifying incomplete firing events and preventing partially-fired components from causing safety hazards.
Implementation Method 1
detecting a temperature of the wellbore using the sensor sub as the perforating gun and the sensor sub are run into the wellbore
Implementation Method 2
detecting an acceleration of the perforating gun and a pressure and a temperature of the wellbore
Implementation Method 3
detecting an acceleration of the perforating gun
Implementation Method 4
calculating a first amount of thermal decomposition undergone by the detonable components of the perforating gun based on the detected temperature of the wellbore
Implementation Method 5
comparing the detected acceleration, pressure, and temperature to benchmark energetic responses for both detonation and deflagration events
Implementation Method 6
comparing the detected acceleration, pressure, and temperature to benchmark energetic responses for both detonation and deflagration events
Data Source
AI summary
A wellbore perforating apparatus and method according to which a perforating gun and a sensor sub are run into a wellbore toward a downhole location at which the wellbore is to be perforated. Detonable components of the perforating gun are energized to perforate the wellbore at the downhole location. An acceleration of the perforating gun and a pressure and a temperature of the wellbore are detected using the sensor sub during a time interval encompassing the energization of the detonable components. The detected acceleration, pressure, and temperature are compared to benchmark energetic responses for both detonation and deflagration events. Based on this comparison, a decision can be made as to whether an incubation period is needed to allow a reaction of the detonable components to weaken before retrieving the perforating gun from the wellbore.