Fiber Optic Current Sensor for Wellbore Ranging Precision
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Solution Overview
Problem
Traditional surveying techniques for determining the relative location of wellbores in steam assisted gravity drainage (SAGD) operations suffer from a widening cone of uncertainty, especially as wellbores lengthen, making precise placement challenging due to unknown current magnitude and distribution along the target wellbore in electromagnetic ranging systems.
Innovation Solution
Deployment of fiber optic current sensors along the target wellbore to measure the current magnitude and distribution, allowing for accurate determination of the relative location of the target wellbore from the drilling wellbore by utilizing fiber optic interrogation systems and responsive cores such as magnetically or electrostrictively responsive materials to detect magnetic and electric field changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional surveying techniques are used for ranging, then the equipment and methods are simple and well-established, but the measurement precision deteriorates as wellbores become longer due to widening cone of uncertainty
Solution Approach 1:
The patent replaces traditional mechanical surveying equipment (inclinometers, gyroscopes) with electromagnetic sensing technology. An electromagnetic sensor system measures the electromagnetic field generated by current flowing through the target wellbore casing, enabling precise ranging measurements that are not degraded by wellbore length. This substitution of measurement physics fundamentally resolves the precision degradation issue.
Solution Approach 2:
The patent introduces an electromagnetic field as an intermediary carrier for measurement information. By flowing current through the target wellbore casing to generate an electromagnetic field, and measuring this field with sensors in the drilling wellbore, the system creates an indirect measurement path that bypasses the limitations of direct mechanical surveying methods.
2Measurement precision
If electromagnetic ranging systems are used with estimated current magnitude, then the system complexity is reduced, but the measurement precision deteriorates due to unknown current distribution
Solution Approach 1:
The patent merges two previously separate functions into a single integrated system: (1) the current injection system that flows current through the target wellbore casing, and (2) the electromagnetic field measurement system that detects the field generated by this current. By combining these functions and using the known current magnitude from the injection system, the patent eliminates the need for separate current estimation, thereby improving ranging accuracy without proportionally increasing overall system 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
Enables precise determination of the distance and direction between wellbores, improving the accuracy of well placement and efficiency of SAGD operations by providing real-time, rotationally invariant measurements of current along the wellbore, thus enhancing the precision and safety of drilling trajectories.
Implementation Method 1
a fiber optic sensor disposed adjacent the conductive member to measure current on the conductive member
Implementation Method 2
an electromagnetic field sensing instrument disposed in the second wellbore to measure an electromagnetic field emanating from the conductive member
Implementation Method 3
responsive cores such as magnetically or electrostrictively responsive materials to detect magnetic and electric field changes
Implementation Method 4
responsive cores such as magnetically or electrostrictively responsive materials to detect magnetic and electric field changes
Data Source
AI summary
A wellbore ranging system and method utilized between first and second wellbores includes an electromagnetic field sensing instrument disposed in the second wellbore, a conductive casing in the first wellbore, an electric current source exciting current flow in the conductive member, and a fiber optic sensor disposed adjacent the conductive member. The current flow along the conductive member results in a magnetic field which is measured by the sensing instrument. The fiber optic sensor includes a core that is responsive to the magnetic field in which it is disposed. The responsive core alters the optical property of an optical wave guide forming the sensor, which altered optical property can be utilized to measure the magnitude of the electrical current at the position of the sensor. The magnitude of the current and the measured magnetic field can be utilized to determine a range between the first and second wellbores.