Downhole ROP Calculation Using Triggered Radiation Source
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Solution Overview
Problem
Existing downhole drilling systems face challenges in accurately determining the rate of penetration (ROP) due to limited space near the drill bit, which hinders the placement of neutron sources and sensors, leading to delayed detection of formation changes.
Innovation Solution
An apparatus and method that utilize a first sensor close to the drill bit to detect formation properties, a radiation source to excite the formation, and a second sensor positioned at a known distance to calculate ROP based on the time duration and distance between the radiation source and sensor activation, allowing for real-time ROP determination without requiring the radiation source and sensor to be close to the drill bit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the neutron source and gamma sensors are placed close to the drill bit to quickly detect formation changes, then the detection speed improves, but the device complexity increases due to space constraints in the BHA
Solution Approach 1:
The system divides the detection function into two separate components: a first sensor placed close to the drill bit for quick formation change detection, and a second sensor placed at a known distance for ROP calculation. This segmentation allows each sensor to be optimally positioned for its specific function without compromising the other.
Solution Approach 2:
The first sensor acts as an intermediary that detects formation property changes and triggers the radiation source. This intermediary mechanism allows the system to respond quickly to formation changes while maintaining a simpler overall device architecture by separating the trigger function from the ROP measurement function.
2Measurement precision
If the radiation source and sensor are placed close to the drill bit, then the ROP calculation accuracy improves, but the reliability decreases due to exposure to harsh downhole conditions
Solution Approach 1:
The system segments the sensor placement strategy by positioning the first sensor close to the drill bit for accurate formation change detection, while placing the second sensor at a distance for reliable ROP calculation. This segmentation allows the second sensor to operate in more favorable conditions, improving overall system reliability.
Solution Approach 2:
The first sensor performs preliminary detection of formation property changes and triggers the radiation source accordingly. This preliminary action allows the second sensor to measure ROP based on pre-triggered events, maintaining accuracy while reducing the second sensor's exposure to harsh conditions.
3Productivity
If the radiation source is continuously activated to maintain detection capability, then the productivity improves, but the loss of energy increases
Solution Approach 1:
The radiation source is activated periodically based on formation property changes detected by the first sensor, rather than continuously. This periodic activation maintains detection capability while significantly reducing energy consumption compared to continuous operation.
Solution Approach 2:
The first sensor provides feedback about formation property changes to the processing unit, which then controls the radiation source activation. This feedback mechanism ensures the radiation source is activated only when needed, optimizing both productivity and energy efficiency.
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 ROP calculation, improving drilling automation, accuracy in wellbore trajectory control, and extending the lifetime of drilling equipment by allowing the radiation source and sensor to be placed away from the drill bit, reducing exposure to harsh conditions.
Implementation Method 1
a radiation source configured to, when triggered, emit radiation to excite a part of the formation
Data Source
AI summary
An apparatus and method for downhole measurement during operation of a drilling system is disclosed. The apparatus (30) comprises: a first sensor (302) configured to detect a property of a subsurface formation (200); a radiation source (304) configured to, when triggered, emit radiation to excite a part (220) of the formation; a processing unit (308) configured to trigger the radiation source if a change of the property of the formation is detected; a second sensor (306) positioned at a known distance from the radiation source and operably connected to the processing unit, the second sensor is configured to detect said excited part of the formation and is more distant from a drill bit (104) of the drilling system than the radiation source is; the processing unit is further configured to, after the excited part of the formation is detected, calculate a rate of penetration of the drill bit based on the following: a time duration between the radiation source is triggered and the excited part of formation is detected, and the distance between the radiation source and the second sensor.