EM Telemetry Resistivity Logging via Conductance
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Solution Overview
Problem
In well drilling and logging operations, it is often economically infeasible to run resistivity logging tools, leaving a gap in direct measurements of formation resistivities around the borehole, which are crucial for fluid presence and reservoir evaluation.
Innovation Solution
The use of electromagnetic telemetry signals to generate formation resistivity logs by processing real-time or historical telemetry data, allowing for the determination of resistivity without the need for a traditional resistivity logging-while-drilling tool, by measuring signal levels at different depths and assigning uniform resistivity values to formation intervals based on conductance calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional resistivity logging tools are used, then direct measurements of formation resistivity are obtained, but the cost of drilling operations increases significantly
Solution Approach 1:
The electromagnetic telemetry system, originally designed solely for data transmission during drilling operations, is repurposed to also measure formation resistivity. By using the same transmitter and receiver infrastructure for both telemetry and resistivity logging, the system eliminates the need for separate dedicated resistivity tools, thereby reducing operational costs while maintaining measurement capabilities
Solution Approach 2:
The system uses its own electromagnetic signals, generated for telemetry purposes, to perform resistivity measurements. The transmitted electromagnetic fields interact with the formation and the returning signals are processed to derive resistivity information, allowing the system to serve dual functions without requiring additional external resources or equipment
2Ease of manufacture
If electromagnetic telemetry signals are used to determine resistivity, then the cost of drilling operations is reduced, but the measurement precision and reliability may be compromised
Solution Approach 1:
The patent replaces the need for complex mechanical resistivity logging tools with an electromagnetic field-based measurement system. By using electromagnetic induction and signal processing techniques, the system achieves resistivity measurements through field interactions rather than direct electrical contact, simplifying the hardware requirements while maintaining measurement accuracy
Solution Approach 2:
The system processes electromagnetic signals by transforming them through mathematical operations to extract resistivity information. By changing the parameters being analyzed (from raw signal strength to derived conductance and resistivity values), the system converts ordinary telemetry data into meaningful formation evaluation metrics, maintaining precision without additional equipment
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
Enables the derivation of formation resistivity logs using EM telemetry signals, providing valuable information for reservoir evaluation and fluid tracking without the necessity of a LWD tool, facilitating faster drilling and accurate well placement.
Implementation Method 1
The transmitting antenna generates electromagnetic fields in the surrounding formation, which in turn induce a response in each receiving antenna
Implementation Method 2
Due to geometric spreading and absorption by the surrounding earth formation, the responses in the receiving antennas have different phases and amplitudes
Implementation Method 3
Due to geometric spreading and absorption by the surrounding earth formation, the responses in the receiving antennas have different phases and amplitudes
Data Source
AI summary
A system includes an electromagnetic logging tool that transmits an electromagnetic signal as the tool is conveyed along a borehole through a formation. The system further includes a processing system that measures a first signal level in response to the tool being at a first measured depth, determines a first conductance based on the first signal level, measures a second signal level in response to the tool being at a second measured depth greater than the first measured depth, the second measured depth and the first measured depth defining a formation interval there between, determines a second conductance based on the second signal level, and assigns a uniform resistivity value to the formation interval based on the first conductance and the second conductance.