Near-bit Resistivity Tool for Real-Time Geosteering
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Solution Overview
Problem
Conventional logging tools are inadequate for real-time geosteering due to their inability to accurately measure formation information close to the drill bit, leading to suboptimal well placement and trajectory control in oil and gas drilling.
Innovation Solution
A downhole drilling system incorporating a near-bit resistivity tool and a deep-reading electromagnetic logging tool, along with a gamma ray detector, which uses iterative forward modeling to refine stratigraphic models based on real-time formation data, enabling precise measurement of formation properties and guiding geosteering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional logging tools are used, then the measurement depth is sufficient to detect formation information, but the measurement location is too far from the drill bit to enable real-time geosteering
Solution Approach 1:
The patent segments the measurement system into two distinct tool arrays: a near-bit array with small transmitter-receiver spacing for close-range formation evaluation, and a deep-reading array with large spacing for distant formation detection. This segmentation allows each array to optimize its measurement capabilities for its specific operational range, resolving the contradiction between measurement accuracy and distance from the drill bit.
Solution Approach 2:
The patent introduces a new dimension by placing measurement arrays at different distances from the drill bit along the tool string. This spatial dimensionality allows simultaneous acquisition of both near-bit and deep-reading formation data, enabling comprehensive formation evaluation that addresses both the accuracy and distance requirements.
2Measurement precision
If deep-reading electromagnetic measurement tools are used, then the formation boundary detection capability is improved, but the real-time geosteering capability remains insufficient
Solution Approach 1:
The near-bit measurement array provides preliminary formation evaluation data close to the drill bit, enabling proactive geosteering decisions before the wellbore deviates from the target zone. This preliminary action at the near-bit level complements the deep-reading boundary detection, ensuring both early warning and precise boundary identification capabilities.
Solution Approach 2:
The patent implements a feedback mechanism where real-time formation data from both near-bit and deep-reading arrays are continuously monitored and used to adjust drilling trajectory. The near-bit array provides immediate feedback for trajectory adjustments, while the deep-reading array provides feedback on approaching formation boundaries, together enabling effective real-time geosteering.
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
This system provides more accurate formation information for real-time geosteering, enhancing well placement and trajectory control by combining near-bit and deep-reading measurements to guide the drill bit effectively.
Implementation Method 1
A transmitter in the first antenna array is placed more than 10 meters away from one of the receivers. This transmitter is configured to transmit electromagnetic signals at one of at least four frequencies in the range of 1 kHz and 200 kHz.
Implementation Method 2
A transmitter in the second antenna array is configured to transmit electromagnetic signals at one of at least two frequencies in the range of 0.2 MHz to 4 MHz.
Implementation Method 3
The downhole drilling system also has a gamma ray detector that reads azimuth gamma ray radiations.
Data Source
AI summary
A downhole drilling tool has a deep-reading logging tool, a near-bit resistivity tool, and a gamma ray detector. Formation information logged using the deep-reading logging tool is used to build a preliminary stratigraphic model with a relatively low resolution. The preliminary stratigraphic model is further refined using data logged using the near-bit resistivity tool and/or the gamma ray detector to obtain a refined stratigraphic model with a higher resolution. The model is used to guide geosteering to achieve better well placement and trajectory control.