Time-reversed nonlinear acoustic downhole pore pressure measurements
US11067711B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Mar 26, 2017 |
| Grant date | Jul 20, 2021 |
| Priority date | — |
| Expiry date | Jul 27, 2037 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V2210/6248
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus (10) and methods for measurement of pore pressure in rock formations through a metal borehole casing (32) after a well is cased and cemented, are described. Such measurements may be accomplished by using the Dynamic Acoustic Elasticity (DAE) method for characterizing nonlinear parameters by perturbing a selected rock formation region with a High Amplitude, Low Frequency (HALF) acoustic strain wave, and probing this region using a Low Amplitude, High Frequency (LAHF) acoustic wave (18), (22). Time reversal techniques (36) may be employed for focusing acoustic energy into the formation in the vicinity of the pipe or open hole. The change in wave speed of the probe pulses as the HALF induced strain wave oscillation propagates through the formation, as a function of the induced strain, may be used to determine the nonlinear elastic parameters α, β, δ, and A of the pore pressure, from which the pore pressure may be determined in the region of the HALF wave.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.