Geosteering Accuracy via Real-Time Geological Model Updates
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Solution Overview
Problem
Conventional geosteering techniques face uncertainties due to sub-seismic resolution stratigraphy and lack of continuity between adjacent wells, leading to inaccurate well placement and geosteering decisions, especially when relying on 1D resistivity models and seismic data.
Innovation Solution
The method involves creating a parameter matrix using true vertical depth (TVD) and measured depth (MD) coordinates from a geological model, updating it with LWD measurements, and calculating weights for geology, DTBB, and other LWD arrays to reconcile differences and update the geological model in real-time during drilling, enabling more accurate geosteering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional geosteering techniques use 1D resistivity models and seismic data, then the process is simple and computationally efficient, but the accuracy of well placement and geological model resolution is insufficient due to sub-seismic resolution stratigraphy and non-unique inversion
Solution Approach 1:
The patent transitions from 1D resistivity models to 2D and 3D geological models by incorporating lateral continuity constraints and spatial relationships between adjacent wells. This dimensional expansion allows the model to capture sub-seismic resolution stratigraphy and resolve non-unique inversion issues through additional spatial constraints, thereby improving well placement accuracy while managing complexity through systematic model construction.
Solution Approach 2:
The patent creates a composite geological model that integrates multiple data sources including seismic data, offset well logs, and real-time LWD measurements. By combining these diverse data types with different resolution characteristics, the model achieves superior accuracy in well placement while maintaining computational tractability through hierarchical integration of data at different scales.
2Measurement precision
If real-time LWD measurements are integrated into geological models, then the resolution of formation properties and accuracy of geosteering decisions improve, but the computational complexity and data processing requirements increase
Solution Approach 1:
The patent performs preliminary integration of offset well logs and seismic data to establish a pre-well geological model before drilling begins. This preliminary action creates a framework that can be efficiently updated with real-time LWD measurements during drilling, reducing the computational burden of real-time processing while maintaining high resolution of formation properties through the pre-established multi-dimensional model structure.
Solution Approach 2:
The patent implements a feedback mechanism where real-time LWD measurements continuously update the geological model during drilling operations. This feedback loop allows the system to resolve non-unique inversion issues and improve well placement accuracy dynamically, while the iterative nature of the updates manages computational complexity by building upon the pre-established model framework rather than recalculating from scratch.
3Ease of operation
If curtain plots are used for visualizing layered earth resistivity models, then real-time geosteering visualization is achieved, but uncertainties remain due to lack of 2D and 3D model complexity and non-unique resistivity inversion
Solution Approach 1:
The patent merges curtain plot visualization with multi-dimensional geological models that incorporate lateral continuity constraints and data from adjacent wells. This combination maintains the real-time visualization ease of curtain plots while eliminating their limitations by integrating them into a broader 2D/3D modeling framework that resolves non-unique inversion issues and provides more accurate geological interpretation through additional spatial constraints.
Data Source
AI summary
Systems and methods for optimized geosteering include creating a parameter matrix, which comprises a formation property for each pair of true vertical depth (TVD) coordinates from a geological model and measured depth (MD) coordinates from a predefined well trajectory; updating the parameter matrix by replacing the TVD coordinates and the MD coordinates for each parameter entry in the parameter matrix with the TVD coordinates and the MD coordinates for an actual well trajectory; and compiling a distance to bed boundary (DTBB) array and one or more other logging while drilling (LWD) arrays using corresponding measurements at the MD coordinates of the actual well trajectory; and calculating a value for each parameter entry in the updated parameter matrix, which is a sum of a geology array, the DTBB array and the one or more other LWD arrays that are each multiplied by respectively assigned or calculated weights.