Azimuthal Formation Measurements for Wellbore Positioning
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Solution Overview
Problem
Current methods for determining the position of a wellbore within subsurface Earth formations are limited by the accuracy and precision of directional sensors and initial models generated from seismic and electromagnetic surveys, leading to uncertainty in maintaining the wellbore trajectory within desired subsurface formations.
Innovation Solution
The method involves generating an initial model of the subsurface structure, drilling a wellbore along a selected trajectory, making azimuthally sensitive formation parameter measurements, and using these measurements to determine distances to formation boundaries, which are then used to adjust and refine the model, thereby improving the precision of wellbore positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional sensors and initial models from seismic surveys are used to determine wellbore position, then the drilling process can be performed, but the accuracy and precision of wellbore positioning is limited
Solution Approach 1:
The patent applies feedback by using azimuthally sensitive formation property measurements to continuously monitor and refine the wellbore position relative to formation boundaries. The measured distances from the wellbore to formation boundaries provide real-time feedback that updates the subsurface model and improves positioning accuracy, allowing operators to adjust the wellbore trajectory to maintain it within desired formations.
Solution Approach 2:
The patent replaces reliance on traditional mechanical directional sensors with azimuthally sensitive formation property measurements. Instead of depending solely on magnetometers and accelerometers that have inherent accuracy limits, the system uses electromagnetic or acoustic measurements that are sensitive to formation properties, providing a different physical basis for positioning that overcomes the limitations of mechanical sensing.
2Measurement precision
If initial models are generated from seismic and electromagnetic surveys, then a subsurface structure model is obtained, but the model accuracy is insufficient for precise wellbore navigation
Solution Approach 1:
The patent uses azimuthal measurements to provide feedback that continuously refines the subsurface model. The measured distances from the wellbore to formation boundaries are compared with the initial model predictions, and the model is updated to reflect actual formation positions. This feedback loop reduces uncertainty and improves model accuracy, allowing for more precise wellbore navigation.
Solution Approach 2:
The patent performs preliminary actions by making azimuthally sensitive formation property measurements at multiple positions along the wellbore before finalizing the updated model. These preliminary measurements provide the data needed to accurately determine distances to formation boundaries, which are then used to refine the model and improve positioning accuracy for subsequent drilling operations.
Data Source
AI summary
A method for determining structure in the Earth's subsurface includes generating an initial model of the structure. The initial model includes at least one layer boundary. A wellbore is drilled along a selected trajectory through the Earth's subsurface in a volume represented by the initial model. At least one formation parameter is measured azimuthally along the wellbore. A distance is determined from the wellbore at selected positions therealong to the at least one layer boundary using the azimuthal formation parameter measurements. The initial model is adjusted using the determined distances. In one example, the parameter is resistivity. In one example, the parameter is acoustic velocity.