Nucleonic Densitometer for Real-Time Drilling Fluid Density
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Solution Overview
Problem
Current methods for determining wellbore stability and hole cleaning efficiency are not accurate in real-time, especially when dealing with multiphase fluids or air gaps, and rely on assumptions for calculating drilling fluid density, which can lead to issues like influx, fracturing, and caving.
Innovation Solution
The use of nucleonic densitometers placed on the return line to measure the density of the return fluid and cuttings in real-time, allowing for the determination of drilling fluid density, flow rates, and other parameters such as equivalent circulating density and pore pressure, thereby improving the accuracy of wellbore stability assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Coriolis flow meters are used to measure return fluid density and flow rate, then measurement capability is provided, but measurement accuracy deteriorates when multiphase fluid or air gaps are present
Solution Approach 1:
The patent replaces the mechanical Coriolis flow meter with a nuclear densitometer that uses gamma-ray attenuation to measure density. This substitution eliminates the problem of air gaps and multiphase fluid interference because the nuclear method measures the average density of the entire fluid column without requiring direct contact with the fluid, thereby maintaining measurement accuracy and reliability under challenging conditions.
2Quantity of substance
If mass balance scales are used to determine cuttings density, then cuttings quantity measurement is provided, but real-time measurement capability is lost due to reliance on correction factors and assumptions
Solution Approach 1:
The patent performs preliminary measurement of the return fluid density continuously as the fluid flows through the pipeline. By measuring the density of the fluid carrying the cuttings in real-time, the system eliminates the need for subsequent correction factors and theoretical calculations, providing immediate and accurate cuttings quantity data without time delays.
3Stress or pressure
If drilling fluid density is controlled based on assumptions and models, then overburden control is achieved, but accuracy deteriorates due to reliance on formation deposition assumptions and original fluid type
Solution Approach 1:
The patent implements a feedback system where the actual return fluid density is continuously measured by the nuclear densitometer and compared against the target density. This real-time feedback allows operators to adjust the drilling fluid density based on actual conditions rather than assumptions, significantly improving the precision of overburden control and preventing wellbore instability issues.
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 real-time monitoring and adjustment of drilling parameters, enhancing hole cleaning efficiency, preventing wellbore instability, and improving the accuracy of formation property assessments by directly measuring fluid density and cuttings content.
Implementation Method 1
a nucleonic densitometer placed on outside of a return line carrying the return fluid from the wellbore
Data Source
AI summary
An apparatus for determining density of fluid returning from a wellbore (“return fluid”) during drilling of the wellbore being drilled using a drill string having a drill bit at an end thereof is disclosed. The apparatus in one embodiment includes a first nucleonic densitometer placed on outside of a return line carrying the return fluid from the wellbore that includes drilling fluid supplied to the drill string and cuttings cut by the drill bit during drilling of the wellbore and a processor that determines the density the return fluid from measurements provided by first nucleonic densitometer.