Predicting Drilling Fluid Sagging via Oscillatory Rheology
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Solution Overview
Problem
Current methods for predicting and detecting static sagging in drilling fluids are time-consuming, inaccurate, and lack reliable on-site monitoring capabilities, leading to inefficiencies in fluid formulation and potential well control issues during extended reach and deep water drilling operations.
Innovation Solution
The development of systems and methods that predict static sagging tendencies by correlating rheological properties, such as flow point and viscoelastic stress, using advanced rheological measurements like oscillatory amplitude sweep and creep-recovery tests, allowing for real-time monitoring and optimization of drilling fluid formulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If static sagging tests are conducted using conventional HPHT aging cells for 7 days or more, then measurement accuracy is improved, but time consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by conducting oscillatory rheology measurements before aging to establish baseline viscoelastic properties (G', G''). These preliminary measurements enable prediction of sagging behavior without waiting for the full 7-day aging period, thus reducing testing time while maintaining accuracy through the predictive correlation between pre-aging rheological properties and post-aging sagging performance.
Solution Approach 2:
The patent replaces the mechanical/physical aging process (7-day HPHT aging requiring direct observation) with rheological measurements (oscillatory tests measuring G' and G''). This substitution allows prediction of sagging tendencies through viscoelastic property analysis, dramatically reducing the time required from weeks to hours while maintaining measurement accuracy through established correlations.
2Ease of operation
If conventional viscosity measurements at low shear rate are used to indicate barite sagging, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent changes the measurement parameter from conventional viscosity (shear-based) to viscoelastic properties (storage modulus G' and loss modulus G'' from oscillatory tests). This parameter change enables more accurate sagging prediction because viscoelastic properties directly reflect the fluid's ability to suspend barite particles, overcoming the limitations of viscosity measurements which show poor correlation with actual sagging behavior.
3Ease of operation
If indirect methods such as density checking or standpipe pressure monitoring are used to detect sagging, then ease of operation is improved, but reliability deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring rheological properties (G', G'') and using these measurements to predict and assess sagging tendencies. This feedback mechanism provides direct information about fluid stability and sagging risk, replacing indirect methods that require inference and interpretation, thereby improving reliability while maintaining ease of operation through automated measurement and prediction systems.
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 rapid prediction of sagging behavior within hours instead of days, reducing product development time, improving measurement efficiency, and enabling real-time decision-making to prevent well control issues, thus enhancing drilling fluid stability and reducing chemical footprints.
Implementation Method 1
predicting at least one flow point of a drilling fluid within an oscillatory rheological measurement range from about 0.1 Hz to about 100 Hz, and/or predicting at least one viscoelastic stress of the drilling fluid within an oscillatory rheological measurement range from about 0.1 Hz to about 100 Hz
Implementation Method 2
characterize, analyze and/or monitor sag in drill or well fluids... based on monitored particle distribution of a fluid mixture as the fluid mixture changes due to gravity
Data Source
AI summary
Systems and methods measure one or more rheological properties and/or parameters of a fluid and establish at least one correlation between the measured one or more rheological properties and/or parameters. The systems and methods may correlate the measured one or more rheological properties and/or parameters to static aging results to establish the at least one correlation between the one or more rheological properties and/or parameters of the fluid. The systems and methods may predict at least one sagging tendency of the fluid based on the established at least one correlation and may measure and/or monitor static sagging of the fluid based on the predicted at least one sagging tendency of the fluid. The systems and methods may guide fluid treatment of the fluid or produce a mud system based on the predicted at least one sagging tendency of the fluid.