Wellbore Fluid Density Measurement Using Gamma-Ray Attenuation
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Solution Overview
Problem
Existing methods for determining the density of drilling fluids in wellbore environments are inaccurate due to continuous changes in fluid composition and pressure-temperature conditions, leading to uncertainties in hydrostatic pressure calculations and operational risks.
Innovation Solution
A method and apparatus for measuring the density of drilling fluids under varying pressure and temperature conditions using a pipe section with integrated densitometers, heat transfer devices, and pressure control systems to establish a PVT model that predicts fluid properties at downhole conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual mud balance measurement is used to determine drilling fluid density, then the measurement process is simple and equipment is readily available, but the measurement precision is limited to about +10kg/m³ and cannot capture continuous variations in fluid composition
Solution Approach 1:
The patent replaces manual mechanical mud balance measurement with an automated gamma-ray densitometry system. The gamma-ray attenuatioin method uses nuclear physics principles to measure density continuously and automatically, achieving precision better than +10kg/m³ while eliminating manual sampling and measurement operations.
Solution Approach 2:
The patent implements continuous online measurement of drilling fluid density through the use of gamma-ray densitometers positioned in the drilling fluid circulation system. This allows continuous monitoring of density variations as fluid composition changes, rather than discrete periodic measurements, enabling real-time detection of composition changes.
2Measurement precision
If density is measured at surface conditions only, then measurement is straightforward, but the density values are inaccurate for downhole conditions due to pressure and temperature variations
Solution Approach 1:
The patent performs preliminary measurements of drilling fluid density at multiple known pressure and temperature conditions using the gamma-ray densitometry system. These preliminary data points are then used to establish PVT correction factors and models that can predict downhole density values, preparing the system in advance for accurate downhole condition assessment.
Solution Approach 2:
The patent systematically varies pressure and temperature parameters during measurement to establish the PVT behavior of the drilling fluid. By measuring density at multiple PVT conditions and fitting these data to empirical models, the system derives correction factors that account for pressure and temperature effects, enabling accurate prediction of downhole density from surface measurements.
3Productivity
If PVT behavior is estimated from component proportions, then calculations are simplified, but uncertainties arise from continuous composition changes that cannot be captured
Solution Approach 1:
The patent implements a feedback mechanism where continuous gamma-ray density measurements are fed into the PVT modeling system. When composition changes are detected through density variations, the system automatically updates the PVT model parameters and recalculates downhole density predictions, ensuring the model remains accurate despite changing fluid composition.
Solution Approach 2:
The patent enables the measurement system to automatically detect composition changes through continuous density monitoring and self-adjust the PVT model parameters without requiring manual intervention. The system serves itself by using its own measurement data to update its predictive models, maintaining reliability while preserving calculation efficiency.
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, continuous, and automated measurement of drilling fluid properties, reducing uncertainties and improving the precision of hydrostatic pressure calculations and operational decisions.
Implementation Method 1
measuring at least one density which is associated with at least one condition of pressure and temperature of the drilling fluid in the pipe section
Implementation Method 2
heat transfer devices
Implementation Method 3
pressure control systems to establish a PVT model
Data Source
AI summary
Methods and an apparatuses are for determining at least one property of a wellbore fluid system. A measurement apparatus having one or more pipe sections is provided, a drilling fluid is communicated through the pipe section, at least one density which is associated with at least one condition of pressure and temperature of the drilling fluid in the pipe section is measured, and the density of the drilling fluid is measured to determine the property of the wellbore fluid system.