Wellbore Trajectory Correction for Non-Circular Survey Legs
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Solution Overview
Problem
Existing wellbore drilling methods using minimum curvature interpolation assume circular arcs between survey stations, leading to inaccuracies in wellbore positioning due to non-circular actual changes in wellbore trajectory, which can result in significant economic losses from stranded hydrocarbon resources.
Innovation Solution
Apply corrections to the measured attitudes at survey stations or interpolate notional stations to ensure modeled well paths accurately reflect the actual change in wellbore position between stations, using additional survey information to minimize positional errors without adding additional data points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum curvature interpolation is used to compute wellbore trajectory between survey stations, then the calculation is simple and efficient, but the positional accuracy deteriorates because the method assumes circular arcs while the actual well path is not circular
Solution Approach 1:
The patent changes the fundamental parameter assumption from circular arc geometry to non-circular arc geometry by using measured inclination and azimuth data at multiple points within the survey interval. This allows the trajectory computation to reflect the actual wellbore path rather than forcing it into a circular arc model, thereby improving positional accuracy while maintaining computational efficiency through the use of standard surveying equations.
Solution Approach 2:
The patent introduces intermediate survey measurements taken at multiple points between the main survey stations as mediators. These intermediate measurements provide additional constraints that allow for more accurate trajectory computation without requiring a complete redesign of the surveying system. The intermediate data acts as a bridge between the simple circular arc model and the complex actual well path.
2Measurement precision
If continuous survey data is collected at many additional points between stationary surveys to improve trajectory accuracy, then the wellbore trajectory computation becomes more accurate, but the operational complexity and data processing requirements increase
Solution Approach 1:
The patent extracts only the essential intermediate measurement data needed for accurate trajectory computation rather than requiring continuous high-frequency surveying. By selecting key intermediate points and using them to constrain the trajectory model, the system achieves high accuracy without the operational burden of continuous surveying at every possible point.
Solution Approach 2:
The patent applies partial action by using a limited number of intermediate survey points rather than continuous surveying. This partial measurement approach provides sufficient constraint for accurate trajectory computation while avoiding the excessive data collection and processing requirements of continuous surveying systems.
Data Source
AI summary
A method of drilling a wellbore to a target includes measuring attitudes at two adjacent survey stations along a wellbore using a downhole surveying tool. An actual change in wellbore position over a survey leg linking the two survey stations is determined. Corrections are applied to the measured attitude at one or both of the survey stations such that a modeled well path joining the survey stations reflects the determined actual change in wellbore positon between the two survey stations.