System And Method for Removing Noise From Measurement Data
AssigneeSchlumberger Technology Corporation
InventorPeter S. Hegeman
Life of this patent
Estimating the term…
Abstract
System and/or methods for removing noise from measurement data are disclosed. For example, pressure measurements may be used to identify a flow regime using the derivative of each of the pressure measurements. A time window may be defined about each pressure measurement and numerous or even all pressure measurements within the time window may be used to calculate the pressure derivative of each pressure measurement. A least-squares method or a least-absolute-deviations method may be used to compute a pressure-derivative curve. The iteratively-reweighted least-squares method may be used to solve least-absolute-deviation problems to compute a pressure-derivative curve with enhanced smoothing.
Claims20
A method comprising:
- drawing reservoir fluid in a formation about a wellbore into a downhole tool;
- ceasing to draw the reservoir fluid into the downhole tool;
- obtaining pressure measurements with respect to time of the reservoir fluid after ceasing to draw the reservoir fluid into the downhole tool;
- defining a time window about a first pressure measurement of the pressure measurements;
- obtaining a derivative of the first pressure measurement with respect to time by utilizing the first pressure measurement, a plurality of the pressure measurements within the time window and obtained prior to the first pressure measurement, and a plurality of the pressure measurements within the time window and obtained after the first pressure measurement;
- and
- identifying a reservoir flow regime based on the derivative.
A method comprising:
- drawing reservoir fluid in a formation about a wellbore into a downhole tool;
- ceasing to draw the reservoir fluid into the downhole tool;
- obtaining pressure measurements of the reservoir fluid with respect to time after ceasing to draw the reservoir fluid into the downhole tool;
- defining a time window about each of the pressure measurements;
- obtaining, for each of the pressure measurements, a derivative of a given pressure measurement of the pressure measurements with respect to time by utilizing the given pressure measurement, a plurality of the pressure measurements within the time window of the given pressure measurement and obtained prior to the given pressure measurement, and a plurality of the pressure measurements within the time window of the given pressure measurement and obtained after the given pressure measurement;
- and
- identifying a reservoir flow regime based on the derivative for each of the pressure measurements.
A method for computing a pressure derivative in a wellbore, the method comprising:
- drawing reservoir fluid in a formation about a wellbore into a downhole tool at a substantially constant rate;
- obtaining pressure measurements of the reservoir fluid with respect to time while drawing reservoir fluid into the downhole tool;
- defining a time window about each of the pressure measurements;
- obtaining, for each of the pressure measurements, a derivative of a given pressure measurement of the pressure measurements with respect to time by utilizing the given pressure measurement, a plurality of the pressure measurements within the time window of the given pressure measurement and obtained prior to the given pressure measurement, and by utilizing a plurality of the pressure measurements within the time window of the given pressure measurement and obtained after the given pressure measurement;
- and
- identifying a flow regime based on the derivative for each of the pressure measurements.
Dependencies are inferred from the claim text.