Downhole Pressure Estimation via Pump Harmonics
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Solution Overview
Problem
Current methods for estimating downhole pressure in hydraulic fracturing, especially in horizontal wells, are inaccurate due to the inability to measure pressure directly and the destruction of pressure gauges by high-rate proppant-laden fluids, leading to uncertain pressure drop predictions and subsequent net pressure calculations.
Innovation Solution
A method and apparatus that estimate pressure head by detecting pump harmonics outside the well using a detector, such as a microseismic array or distributed fibre-optic vibration sensor, allowing for real-time pressure head determination without the need for downhole sensors, even in high-rate and long horizontal well treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure gauge is placed inside the propagating fracture to measure pressure directly, then measurement precision is improved, but the pressure gauge will be destroyed by high-rate proppant-laden fluid
Solution Approach 1:
The patent uses an intermediary approach by placing the pressure gauge in a monitoring well adjacent to the treatment well rather than directly in the propagating fracture. The pressure gauge measures pressure in the monitoring well, which communicates pressure information from the treatment well through the formation, thereby avoiding direct exposure to destructive proppant-laden fluid while still obtaining pressure measurement data
Solution Approach 2:
The patent creates a copy of the pressure measurement environment by using a separate monitoring well that replicates the pressure conditions of the treatment well. The pressure gauge measures pressure in this copied environment, which reflects the actual fracture pressure without the harmful elements present in the original treatment well
2Reliability
If pressure is measured in a monitoring well to avoid gauge destruction, then device reliability is improved, but measurement precision deteriorates when there is no pressure communication between wells
Solution Approach 1:
The patent changes the measurement location parameter from the treatment well to an adjacent monitoring well, and further changes to multiple monitoring wells at different locations. By selecting monitoring wells with appropriate pressure communication characteristics, the system maintains measurement precision while ensuring gauge reliability
3Ease of operation
If pressure drop is predicted for horizontal wells using multiphase flow models, then ease of operation is improved, but measurement precision deteriorates due to uncertainty in predicting complex multiphase flow conditions
Solution Approach 1:
The patent replaces complex multiphase flow mechanical modeling with a simpler acoustic wave propagation model. By treating the pressure wave as an acoustic signal traveling through the fluid column, the system avoids the complexities of multiphase flow dynamics while achieving accurate pressure head estimation through acoustic travel time measurements
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
Provides accurate and real-time pressure head estimates, enabling better control of hydraulic fracturing operations and improved fracture modeling by eliminating the need for downhole pressure gauges and improving the accuracy of pressure drop predictions in challenging well conditions.
Implementation Method 1
the pump or pumps pumping fluid into the well generate vibrations that are transmitted through the fluid at an harmonic frequency
Implementation Method 2
a detector that is not in contact with the fluid detects the vibrations and measures the energy of the received vibrations at the harmonic frequency
Data Source
AI summary
A method for estimating downhole pressure in wells during a treatment procedure. A pressure head in a treatment well may be determined without requiring downhole sensors. The method for measuring downhole pressure may be used in long horizontal wells. By improving the accuracy of such pressure head estimates and providing the data substantially in real time, the data can also be used to control the treatment being applied to the well. The pressure head may be determined by detecting pump harmonics at a detector, typically positioned outside of the well and/or not in direct contact with the fluid in the well. The detector may be a microseismic array.