Log Correlation for Horizontal Wellbore Placement Accuracy
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Solution Overview
Problem
Horizontal drilling in hydrocarbon-bearing formations faces challenges due to the need for precise placement of horizontal boreholes, which is complicated by physical phenomena like faulting and differential compaction, leading to inaccuracies in targeting economically viable zones.
Innovation Solution
A method and system for correlating predicted logs with measured logs during drilling, allowing for real-time adjustments to the drilling direction by using MWD tools and LWD tools to create modeled surfaces that accurately reflect the formation's dip, enabling more precise placement of horizontal wellbores within target zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional drilling methods are used to place horizontal boreholes, then the drilling process can be completed, but the placement accuracy of the horizontal borehole within the target zone is insufficient due to physical phenomena like faulting and differential compaction
Solution Approach 1:
The patent applies preliminary action by creating a predicted log before drilling to establish the expected formation characteristics and target zone locations. This predicted log serves as a pre-planning tool that guides the drilling process, allowing operators to anticipate formation variations due to faulting and differential compaction before encountering them in the field.
Solution Approach 2:
The patent implements feedback by continuously comparing the predicted log with the measured log obtained from MWD and LWD tools during drilling. This real-time correlation allows operators to detect deviations from the planned trajectory and adjust drilling parameters to maintain accurate placement within the target zone, compensating for physical phenomena like faulting and differential compaction.
2Measurement precision
If the true vertical depth of target zones is adjusted as a function of horizontal location to account for faulting and differential compaction, then the accuracy of target zone identification improves, but the complexity of the drilling process increases
Solution Approach 1:
The patent applies universality by using a single integrated system that performs multiple functions: it generates the predicted log, acquires MWD and LWD data during drilling, correlates the logs in real-time, and provides trajectory guidance. This multi-functional approach consolidates what would otherwise require separate processes, managing the complexity of accounting for faulting and differential compaction through one unified workflow.
Solution Approach 2:
The patent uses the log correlation process as an intermediary that bridges the gap between the predicted formation model and the actual measured data. This intermediary step translates complex geological variations into actionable guidance for drill placement, simplifying the decision-making process while maintaining high accuracy in target zone identification.
3Manufacturing precision
If MWD tools and LWD tools are used to create modeled surfaces that reflect formation dip, then the accuracy of wellbore placement improves, but the amount of equipment and data processing required increases
Solution Approach 1:
The patent applies merging by combining MWD and LWD tools into a single integrated drilling system that simultaneously collects both directional drilling data and formation evaluation data. This consolidation allows for real-time creation of modeled surfaces reflecting formation dip without requiring separate equipment deployments, managing the complexity through integrated data acquisition.
Solution Approach 2:
The system applies self-service by using the data collected from MWD and LWD tools to automatically update the predicted log and recalculate optimal drill placement in real-time. The system processes its own data to provide continuous guidance, reducing the need for external intervention and manual analysis while maintaining high precision in wellbore placement.
Data Source
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AI summary
Correlating a measured and predicted log. At least some illustrative embodiments are methods including: plotting values of the measured log with respect to an ordinate axis and an abscissa axis, and the plotting in a first pane; plotting values of the predicted log with respect to the ordinate axis and the abscissa axis; selecting an inflection point of the predicted log; shifting horizontal position of the inflection point relative to the measured log responsive to the pointing device; changing dip of at least one modeled surface in a structural model based the relative location of the inflection point; recalculating the predicted log based on the change in dip, the recalculating creates a modified predicted log; and then plotting the modified predicted log. In some cases, the method may also include adding a fixed X,Y,Z point in the at least one modeled surface based on location of the inflection point.