Downhole characterization of formation pressure

Patent metadata

Field	Value
Publication number	US-2018371902-A1
Application number	US-201816014475-A
Country	US
Kind code	A1
Filing date	Jun 21, 2018
Priority date	Jun 21, 2017
Publication date	Dec 27, 2018
Grant date	—

Abstract

A method includes operating a downhole acquisition tool in a wellbore in a geological formation and performing formation testing to determine at least one measurement associated within the formation, the wellbore, or both. The tool may include sensors to detect measurements including, for example, formation pressure and/or wellbore pressure. The tool may also include a processor to obtain at least one spectral characteristic associated with the measurement, which may include frequencies of oscillation. The processor may also determine one or more parameters, associated with an oscillation suppression process, based on the spectral characteristic and remove oscillations, including noise associated with fluctuations of a fluid level in the wellbore, in the measurement based on the parameters. Petrophysical parameters may be estimated based on the modified measurement.

First claim

1 . A method comprising:
operating a downhole acquisition tool in a wellbore in a geological formation; performing formation testing using the downhole acquisition tool in the wellbore to determine at least one measurement associated within the geological formation, the wellbore, or both, wherein the downhole acquisition tool comprises one or more sensors configured to detect the at least one measurement, and wherein the at least one measurement comprises formation pressure, wellbore pressure, or both; using a processor of the downhole acquisition tool to:
obtain at least one spectral characteristic associated with the at least one measurement, wherein the at least one spectral characteristic comprises frequencies of oscillation of the at least one measurement;
determine one or more parameters, associated with an oscillation suppression process, based at least in part on the at least one spectral characteristic;
remove oscillations in the at least one measurement based at least in part on the one or more parameters to generate a modified measurement, wherein the oscillations comprise noise associated with fluctuations of a fluid level in the wellbore; and
estimating at least one petrophysical parameter of the geological formation, the wellbore, or both based at least in part on the modified measurement.

2 . The method of claim 1 , wherein the processor removes the oscillations in the at least one measurement by attenuating a first set of frequencies of the at least one measurement associated with the oscillations while retaining a second set of frequencies of the at least one measurement associated with a pressure change in the formation pressure, wellbore pressure, or both, and wherein the second set of frequencies comprises an amplitude that is above a threshold amplitude.

3 . The method of claim 2 , wherein the pressure change is in response to pumping the fluid into the wellbore.

4 . The method of claim 4 , using a filter to remove the oscillations in the at least one measurement during the oscillation suppression process.

5 . The method of claim 1 , wherein the filter comprises a low-pass filter, a band-stop filter, or both.

6 . The method of claim 5 , wherein the one or more parameters comprises at least one threshold frequency of the oscillations, and wherein the filter blocks transmission of the oscillations above the at least one threshold frequency.

7 . The method of claim 4 , comprising applying a Wiener-E filter to the at least one measurement to remove the oscillations, wherein the Wiener-E filter comprises a Wiener filter followed by an E filter.

8 . The method of claim 4 , comprising applying a Wiener-E filter to the at least one measurement to remove the oscillations, wherein the Wiener-E filter comprises a Wiener filter comprising a median filter.

9 . The method of claim 1 , wherein the petrophysical parameter comprises an estimated formation pressure.

10 . The method of claim 1 , wherein the at least one measurement comprises a wellbore measurement and a formation measurement, and wherein the oscillations in the formation measurement are removed based at least in part on the one or more parameters determined based at least in part on the spectral characteristic based at least in part on the wellbore measurement.

11 . One or more tangible, non-transitory, machine-readable media comprising instructions configured to:
receive at least one measurement of a geological formation, a wellbore, or both, as measured by a downhole acquisition tool in the wellbore in the geological formation, wherein the wellbore contains a fluid, wherein the at least one measurement comprises oscillations associated with changes in an amount of the fluid within the wellbore, and wherein the at least one measurement comprises formation pressure, wellbore pressure, or both;
determine one or more parameters associated with an oscillation suppression process based at least in part on a spectral characteristic of the at least one measurement, wherein the spectral characteristic comprises frequencies of oscillation of the at least one measurement;
remove oscillations in the at least one measurement based at least in part on the one or more parameters to generate a modified measurement; and
estimate at least one petrophysical property of the geological formation, the wellbore, or both, based at least in part on the modified measurement.

12 . The one or more tangible, non-transitory, machine-readable media of claim 11 , wherein the oscillations comprise an induced noise associated with the downhole acquisition tool.

13 . The one or more tangible, non-transitory, machine-readable media of claim 11 , wherein the instructions are configured to remove the oscillations in the at least one measurement by attenuating a set of frequencies of the at least one measurement associated with the oscillations.

14 . The one or more tangible, non-transitory, machine-readable media of claim 11 , wherein the modified measurement comprises pressure data characterizing a pressure change in the formation pressure, wellbore pressure, or both.

15 . The one or more tangible, non-transitory, machine-readable media of claim 11 , wherein the at least one petrophysical property comprises a pressure derivative of the formation pressure, the wellbore pressure, or both.

16 . A system, comprising:
a downhole acquisition tool housing comprising one or more sensors configured to measure at least one measurement of a geological formation of a hydrocarbon reservoir, a wellbore within the geological formation, or both, wherein the at least one measurement comprises oscillations corresponding to a mud-cake permeability, wherein the at least one measurement is a pressure or a frequency spectrum of the pressure; and a data processing system comprising one or more tangible, non-transitory, machine-readable media comprising instructions configured to:
receive the at least one measurement from the downhole acquisition tool;
determine one or more parameters associated with an oscillation suppression process based at least in part on the at least one measurement;
attenuate one or more frequencies associated with the oscillations in the at least one measurement;
retain frequency components of the at least one measurement having an amplitude above a threshold amplitude to generate a modified measurement; and
estimate a formation production parameter based at least in part on the modified measurement, wherein the modified measurement is a pressure measurement.

17 . The system of claim 16 , wherein the data processing system is configured to determine a filter parameter of one or more non-linear filters to attenuate the one or more frequencies.

18 . The system of claim 17 , wherein the one or more non-linear filters comprises a Wiener-E filter, and wherein the filter parameter comprises mean absolute deviation values, mean pressure values, or both.

19 . The system of claim 16 , wherein the one or more sensors comprises a strain gauge, quartz gauge, or both.

20 . The system of claim 16 , wherein the data processing system is disposed within the downhole acquisition tool housing or outside the downhole acquisition tool housing at a wellbore surface.

Assignees

• Schlumberger Technology Corp

Inventors

• Li Jiyao
• Ramakrishnan Terizhandur S

Classifications

• E21B49/008 Primary

  by injection test; by analysing pressure variations in an injection or production test, e.g. for estimating the skin factor (measuring pressure E21B47/06) · CPC title

• E21B49/0875

  determining specific fluid parameters · CPC title

• E21B49/084

  with means for conveying samples through pipe to surface · CPC title

• E21B47/06

  Measuring temperature or pressure · CPC title

• E21B49/088 Primary

  combined with sampling · CPC title