Wellbore Annulus Flow Classification for Hole Cleaning Pressure Control
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Solution Overview
Problem
Current methods for monitoring and controlling bottom hole pressure in drilling operations, especially in narrow mud windows and Managed Pressure Drilling, face challenges due to high cuttings concentration and friction losses, which can lead to pressure loss and blockages in the wellbore, requiring improved prediction and estimation of flow patterns and cuttings concentration.
Innovation Solution
The use of dimensionless parameters to classify flow patterns as stationary bed, dispersed, or transitional flows, allowing for accurate modeling of pressure gradients and cuttings concentration, and the implementation of a computing system to estimate and control drilling fluid flow rates based on these classifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow rate of the drilling fluid is low, then the concentration of cuttings in the annulus increases, but pressure loss increases due to high cuttings concentration
Solution Approach 1:
The patent applies parameter changes by using dimensionless parameters (such as the particle Froude number and Reynolds number) to characterize and predict flow patterns. By changing and monitoring these parameters, the system can identify transitions between flow regimes (e.g., from dispersed flow to stationary bed flow) and adjust operating conditions to maintain optimal pressure loss while ensuring effective hole cleaning at different flow rates
2Productivity
If the flow rate of the drilling fluid is high, then friction loss increases, but pressure loss increases due to high friction effects
Solution Approach 1:
The patent employs feedback mechanisms by continuously monitoring flow rate, pressure loss, and dimensionless parameters to detect changes in flow pattern. This feedback allows the system to adjust the flow rate dynamically to maintain optimal drilling conditions, balancing hole cleaning effectiveness with pressure loss management in real-time
3Reliability
If the concentration of cuttings in the annulus is high, then hole cleaning effectiveness improves, but pressure loss increases
Solution Approach 1:
The patent replaces direct mechanical measurement of cuttings concentration and flow pattern with a field-based approach using dimensionless parameters. By substituting complex mechanical measurements with calculations based on measurable quantities (flow rate, pressure gradient, fluid properties), the system can predict flow patterns and cuttings concentration indirectly, enabling optimization without direct intervention in the flow mechanics
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 enables more accurate prediction and control of pressure gradients and cuttings concentration, reducing pressure loss and blockages, thereby enhancing drilling efficiency and safety by considering both hole cleaning and pressure profile jointly.
Implementation Method 1
The flow within such a flow conduit may include multiple phases. The phases include a liquid phase (e.g., drilling fluid) and a particle phase (e.g., cuttings formed by a drill bit of the drill string during drilling)
Implementation Method 2
Pressure loss in the wellbore may be due to the effects of cuttings and/or friction effects. When the flow rate of the drilling fluid is high, friction loss may become high, which can also lead to high pressure loss
Implementation Method 3
The dimensionless parameters include a first dimensionless parameter corresponding to an effect of turbulence on the flow and a second dimensionless parameter corresponding to an effect of gravity on the flow
Implementation Method 4
The dimensionless parameters include a first dimensionless parameter corresponding to an effect of turbulence on the flow
Data Source
AI summary
A system includes a processor. The processor estimates a pattern of a flow of a mixture of drilling fluid and cuttings in an annulus of a wellbore. The flow is estimated as a stationary bed flow, a dispersed flow, or a transitional flow relative to the stationary bed and dispersed flows. The processor estimates parameters based on the estimated pattern of the flow, and determines a plurality of dimensionless parameters including a first dimensionless parameter corresponding to an effect of turbulence on the flow and a second dimensionless parameter corresponding to an effect of gravity on the flow, based on the estimated parameters. The processor characterizes the pattern of the flow as the stationary bed flow, the dispersed flow, or the transitional flow, based on the dimensionless parameters, and models the flow based on the estimated pattern if it is determined that the characterized pattern matches the estimated pattern.