Instrumented Drill Bit Resistivity Measurement
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Solution Overview
Problem
The invasion of drilling mud into the formation surrounding the borehole affects accurate resistivity measurements, making it challenging to detect strata boundaries and predict hydrocarbon production effectively.
Innovation Solution
An instrumented drill bit assembly with an electromagnetic wave antenna and receivers is used to measure formation resistivity close to the bit, allowing for resistivity determination in the presence of conductive or non-conductive drilling fluids, and tilted antennas enable measurements ahead of the bit, reducing the impact of mud invasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistivity measurements are taken in the borehole, then measurements can be obtained, but drilling mud invasion into the formation contaminates the measurement zone and reduces measurement accuracy
Solution Approach 1:
The patent transitions from traditional borehole-based resistivity measurements to measurements taken at the bit face, utilizing the spatial dimension at the drilling interface. By positioning measurement electrodes on the bit assembly rather than in the borehole, the system measures resistivity at the boundary between the flushed zone and undisturbed formation, effectively avoiding contamination by drilling mud while maintaining measurement capability.
Solution Approach 2:
The patent performs resistivity measurements before the drilling mud can fully invade and contaminate the formation. By conducting measurements at the bit face during or immediately after drilling, the system captures resistivity data from the undisturbed formation zone before the harmful effect of mud invasion propagates to the measurement location.
2Measurement precision
If measurements are taken close to the bit, then mud invasion effects are reduced, but detecting strata boundaries ahead of the bit becomes more difficult
Solution Approach 1:
The patent employs dynamic measurement capabilities that can adapt to different measurement objectives. The bit assembly includes multiple electrodes and measurement systems that can dynamically adjust their measurement zone and detection depth based on the drilling conditions and formation characteristics, enabling both accurate near-bit measurements and effective boundary detection ahead of the bit when needed.
Solution Approach 2:
The system utilizes the spatial dimension at the bit face to simultaneously achieve both goals: measuring resistivity close to the bit to avoid mud invasion effects while also detecting strata boundaries ahead of the bit through appropriately positioned electrodes and measurement zones that extend into the formation ahead of the bit face.
3Measurement precision
If traditional borehole transducers are used, then resistivity can be measured, but the measurement is affected by the flushed zone created by drilling mud filtrate
Solution Approach 1:
The patent extracts the measurement function from the contaminated borehole environment and relocates it to the bit face, where the measurement electrodes can directly contact the formation without interference from drilling mud filtrate. This extraction of the measurement process from the harmful environment preserves the integrity of the formation resistivity information.
Solution Approach 2:
The bit assembly serves as an intermediary platform that bridges the drilling operation and formation measurement. By positioning measurement electrodes on the bit face, the system creates a measurement interface that is free from drilling mud contamination while maintaining direct contact with the formation, thus preserving accurate resistivity information.
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 approach provides accurate and reliable resistivity measurements, enabling better detection of strata boundaries and prediction of hydrocarbon production by minimizing the effects of mud invasion and allowing for resistivity imaging around the borehole.
Implementation Method 1
An instrumented drill bit assembly with an electromagnetic wave antenna and receivers is used to measure formation resistivity close to the bit
Data Source
AI summary
An apparatus for measuring a resistivity of a formation comprising an instrumented bit assembly coupled to a bottom end of the apparatus. At least one first electromagnetic wave antenna transmits an electromagnetic wave signal into the formation. At least one second electromagnetic wave antenna located on the instrumented bit assembly and longitudinally spaced apart from the at least one first electromagnetic wave antenna receives the electromagnetic wave signal transmitted through the formation. Electronic circuitry is operably coupled to the at least one second electromagnetic wave antenna to process the received signal to determine a resistivity of the formation proximate the instrumented bit assembly.