Electromagnetic Wellbore Ranging Using Casing Excitation
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Solution Overview
Problem
Current methods for determining the relative location of wellbores in steam assisted gravity drainage (SAGD) processes are inefficient, requiring multiple teams and equipment in both wellbores, and previous technologies for single-wellbore solutions have low current transfer efficiency, leading to inaccurate positioning and reduced process efficiency.
Innovation Solution
A system and method using a conductive body in the target wellbore with a drill string carrying a measurement-while-drilling system, an electric current supply to excite an alternating current flow, and an electromagnetic field sensing instrument in the second wellbore to measure the magnetic field and radial gradients, optimizing sensor placement and current injection for precise distance and direction determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two separate teams and equipment are deployed in both wellbores for ranging, then measurement capability is improved, but operational complexity and cost increase
Solution Approach 1:
The invention extracts the ranging measurement capability from the target wellbore equipment and concentrates it entirely in the drilling wellbore. The magnetic field sensor and signal processing equipment are placed only in the drilling wellbore, while the target wellbore serves only as a passive magnetic source, eliminating the need for equipment teams in both wellbores.
Solution Approach 2:
The target wellbore casing serves multiple functions: it acts as the structural wellbore containment and simultaneously functions as the magnetic field source for ranging measurements. By inducing current in the conductive casing, the same physical structure provides both mechanical and electromagnetic functions.
2Device complexity
If current transfer efficiency is reduced in single-wellbore solutions, then equipment complexity is reduced, but positioning accuracy deteriorates
Solution Approach 1:
The invention changes the electrical parameters by inducing alternating current at optimized frequencies (typically 1-100 Hz) in the target wellbore casing. This frequency selection maximizes magnetic field penetration and signal strength while minimizing interference, thereby improving positioning accuracy without adding complex equipment.
Solution Approach 2:
The invention replaces direct electrical connection or mechanical contact-based ranging methods with electromagnetic field-based measurement. By using magnetic field sensors to detect the alternating magnetic field generated by induced current, the system achieves accurate positioning without requiring physical contact or high current transfer efficiency.
3Productivity
If wellbores are drilled at very small distances, then SAGD process efficiency is improved, but positioning margin requirements increase
Solution Approach 1:
The invention implements real-time feedback by continuously measuring the magnetic field strength and direction as the drilling wellbore progresses. The measured magnetic field parameters are fed back to adjust the drilling trajectory, enabling precise positioning with small margins through active control rather than passive tolerance management.
Solution Approach 2:
The invention performs preliminary ranging measurements during the drilling process itself, allowing trajectory adjustments to be made while the wellbore is still being drilled. This preliminary action prevents the need for large positioning margins by correcting deviations before they become significant errors.
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 precise determination of distance and direction between wellbores with high accuracy and efficiency, reducing operational costs and improving SAGD process effectiveness by enabling precise wellbore placement, even in close proximity, thus enhancing oil extraction.
Implementation Method 1
an electromagnetic field sensing instrument in the second wellbore being drilled, the electromagnetic field sensing instrument being responsive to the electromagnetic field and to radial gradients of the electromagnetic field generated by the electrical current in the target wellbore
Implementation Method 2
an electric current supply disposed to excite a current flow on the target wellbore by a direct electrical connection to the target wellbore
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A system for ranging between two wellbores. The target wellbore includes a conductive body (e.g., casing) disposed within a portion of the target wellbore. A second wellbore includes an electromagnetic field sensing instrument positioned within the wellbore. A current delivered to the conductive body in the target wellbore results in a magnetic field emanating from the target wellbore. The electromagnetic field sensing instrument is utilized to measure an electromagnetic gradient based on the magnetic field, which electromagnetic gradient can be utilized to determine the range between the wellbores.