Deep Directional Resistivity Logging Workflow for Oil-Water Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Deep directional electromagnetic logging-while-drilling technologies face challenges in complex geological scenarios where 1D multi-layer models are inadequate for accurate real-time interpretation, particularly in determining the oil-water contact (OWC) in dipping formations, due to insufficient information and computational complexity of 2D inversion models.
Innovation Solution
A multi-step workflow is introduced that gradually builds a reliable 1D model using deep directional resistivity measurements, involving measurement sensitivity analysis, local residual weighted averaging, and smoothing post-processing, followed by 2D inversion to accurately determine the OWC position and resistivity, stabilizing the interpretation process and maximizing measurement value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 1D multi-layer model-based inversion is used for real-time interpretation, then the interpretation process is simple and fast, but the accuracy is insufficient in complex geological scenarios with dipping formations
Solution Approach 1:
The patent segments the inversion process into multiple steps: first performing 1D multi-layer model-based inversion to obtain preliminary formation parameters, then using these results as input for 2D inversion to accurately determine OWC position. This segmentation allows the complex 2D inversion to be performed only when needed, balancing accuracy requirements with computational complexity.
Solution Approach 2:
The patent performs preliminary 1D inversion before 2D inversion, using the 1D results as initial inputs for the 2D inversion process. This preliminary action prepares the data in advance, making the subsequent 2D inversion more efficient and accurate while avoiding direct computation of the full 2D problem from scratch.
2Measurement precision
If 2D inversion is performed directly to accurately determine OWC position in dipping formations, then the accuracy is improved, but the computational complexity and processing time increase significantly
Solution Approach 1:
The patent divides the inversion workflow into sequential stages: 1D inversion is performed first for rapid preliminary interpretation, followed by targeted 2D inversion only for complex scenarios. This segmentation reduces overall processing time while maintaining accuracy where needed.
Solution Approach 2:
The 1D inversion serves as a preliminary step that prepares formation parameters and identifies potential complex scenarios. By performing this preliminary action, the system avoids unnecessary full 2D inversions in simple cases, thereby reducing processing time while maintaining the capability for accurate 2D analysis when required.
3Ease of operation
If standard inversion-based answer product is used, then the process is straightforward, but it does not account for flat OWC and dipping formation layers adequately
Solution Approach 1:
The patent implements a dynamic interpretation workflow that adapts to formation complexity. The system automatically transitions from simple 1D inversion to more sophisticated 2D inversion when geological features such as dipping layers or flat OWC are detected, ensuring reliability while maintaining operational simplicity through automated decision-making.
Solution Approach 2:
The patent introduces an intermediary analysis step between 1D and 2D inversion that evaluates formation characteristics and determines the appropriate inversion level. This intermediary acts as a mediator that ensures the right level of complexity is applied, maintaining both workflow simplicity and detection reliability.
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
The workflow effectively enhances the accuracy of OWC positioning and resistivity determination, even in complex formations, by stabilizing the interpretation process and reducing ambiguity, thereby improving the quality of real-time decision-making in well placement.
Implementation Method 1
deep directional electromagnetic logging-while-drilling technology... relying on directional sensitivity measurements
Implementation Method 2
deep directional resistivity measurements... enable detection of boundaries and contacts
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Methods for determining oil-water contact positions and water zone resistivities are provided. In one example, the method may involve performing a 1D inversion on data collected by a resistivity logging tool. Further, the method may involve scanning a resistivity profile of a reservoir generated by the 1D inversion for a boundary position below the resistivity logging tool. Furthermore, the method may involve applying a local residual weighted average on the boundary position to generate an initial estimation of an oil-water contact position and inverting the initial estimation of the oil-water contact to generate water zone resistivity and a modified oil-water contact position. Additionally, the method may involve running a smoothing local post-processing operation to generate a layered model and performing a 2D inversion on the layered model.