Hydraulic Fracture Closure Pressure Determination via Pulse Propagation
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Solution Overview
Problem
Current methods for determining hydraulic fracture closure pressure are inconvenient and not commonly used under field conditions due to the need for complex equipment setups, such as maintaining a constant withdrawal rate during injection/withdrawal tests.
Innovation Solution
A method that involves creating a mathematical simulation model of pressure pulse propagation within the wellbore and fracture, sending pressure pulses, recording responses, and extrapolating the ratio of simulated average fracture width to zero-width to determine closure pressure, using existing fracturing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If injection/withdrawal tests are used to determine closure pressure, then closure pressure can be determined through pressure decay rates, but complex equipment setups are required to maintain constant withdrawal rate
Solution Approach 1:
The method uses the existing fracturing pump itself to generate the pressure pulses needed for measurement, rather than requiring separate injection/withdrawal equipment. The pump's normal operation provides the test signals, eliminating the need for additional complex equipment setups while maintaining measurement capability
Solution Approach 2:
The method extracts only the essential measurement function from the complex injection/withdrawal test setup. By analyzing pressure pulses naturally occurring during fracturing operations, it separates the closure pressure determination from the need for constant rate maintenance equipment, keeping only what is necessary for the measurement
2Productivity
If pressure pulses are sent during fracturing operations, then closure pressure can be determined in real-time without stopping operations, but additional equipment may be needed to generate pulses
Solution Approach 1:
The fracturing pump is used to generate both the fracturing pressure and the measurement pressure pulses. By modulating the pump's operation or utilizing natural pressure fluctuations during injection, the system performs self-measurement without requiring separate pulse generation equipment, maintaining continuous operation while avoiding additional complexity
Solution Approach 2:
The existing fracturing equipment is made multi-functional by using it for both the primary fracturing operation and the closure pressure measurement. The same pump and pressure system serve dual purposes, eliminating the need for dedicated measurement equipment and enabling continuous operation
Data Source
AI summary
The method relates to the field of hydraulic fracturing of subsurface formations. A mathematical simulation model of a pressure pulse propagation inside a wellbore and inside a fracture is created. Pressure pulses are sent to the wellbore, and the response of the well to the pressure pulses is registered. Then, a bottom-hole pressure corresponding to each pulse is determined. An average fracture width is derived by using the mathematical simulation model of pressure pulse propagation inside the wellbore and inside the fracture, and a ratio between the simulated average fracture width and the determined bottom-hole pressure is determined. The said ratio is extrapolated to a zero-width point, and the closure pressure is determined as the bottom-hole pressure corresponding to the zero width.