System and method for real-time management of formation fluid sampling with a guarded probe
First Claim
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1. A method, comprising:
- conveying a wellbore tool in a wellbore extending into an earth formation, wherein;
the wellbore tool comprises a fluid sampling device;
the fluid sampling device comprises;
an inner probe configured to withdraw a first fluid sample from the formation; and
an outer probe surrounding the inner probe and configured to withdraw a second fluid sample from the formation;
urging the fluid sampling device into contact with a wall of the wellbore;
withdrawing the first and the second fluid samples from the formation while;
maintaining the inner probe at a first pressure; and
maintaining the outer probe at a second pressure, wherein the first pressure is higher than the second pressure;
determining a first contamination amount of the first fluid sample using an optical fluid analysis (OFA) sensor;
determining a second contamination amount of the second fluid sample using the OFA sensor;
determining in real-time a difference between the first and second contamination amounts;
confirming correct operation of the fluid sampling device by determining in real-time a maximum of the difference between the first and second contamination amounts;
extrapolating future values for the difference between the first and second contamination amounts by;
normalizing the first and second contamination amounts using initial values of the first and second contamination amounts determined upon commencement of withdrawing the first and second fluid samples; and
fitting to a power-law model the determined difference between the first and second contamination amounts;
determining from the extrapolated future values a time at which the difference between the first and second contamination amounts will reach a minimum;
continuing withdrawing of the first and second fluid samples until reaching the determined time; and
theninitiating collection of a portion of the first fluid sample.
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Abstract
Embodiments of the present invention relate to systems and methods for real-time management of formation fluid sampling down a wellbore using a guarded probe. More specifically, but not by way of limitation, embodiments of the present invention provide for management of downhole fluid sampling by sensing properties of fluids collected by a downhole-fluid-sampling-device, modeling the fluid sampling process from these sensed properties and using the modeling of the fluid sampling process to manage in real-time the fluid sampling process.
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2 Claims
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1. A method, comprising:
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conveying a wellbore tool in a wellbore extending into an earth formation, wherein; the wellbore tool comprises a fluid sampling device; the fluid sampling device comprises; an inner probe configured to withdraw a first fluid sample from the formation; and an outer probe surrounding the inner probe and configured to withdraw a second fluid sample from the formation; urging the fluid sampling device into contact with a wall of the wellbore; withdrawing the first and the second fluid samples from the formation while; maintaining the inner probe at a first pressure; and maintaining the outer probe at a second pressure, wherein the first pressure is higher than the second pressure; determining a first contamination amount of the first fluid sample using an optical fluid analysis (OFA) sensor; determining a second contamination amount of the second fluid sample using the OFA sensor; determining in real-time a difference between the first and second contamination amounts; confirming correct operation of the fluid sampling device by determining in real-time a maximum of the difference between the first and second contamination amounts; extrapolating future values for the difference between the first and second contamination amounts by; normalizing the first and second contamination amounts using initial values of the first and second contamination amounts determined upon commencement of withdrawing the first and second fluid samples; and fitting to a power-law model the determined difference between the first and second contamination amounts; determining from the extrapolated future values a time at which the difference between the first and second contamination amounts will reach a minimum; continuing withdrawing of the first and second fluid samples until reaching the determined time; and
theninitiating collection of a portion of the first fluid sample.
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2. An apparatus, comprising:
a wellbore tool configured for conveyance in a wellbore extending into an earth formation, comprising; a fluid sampling device comprising; an inner probe configured to withdraw a first fluid sample from the formation; and an outer probe surrounding the inner probe and configured to withdraw a second fluid sample from the formation; means for urging the fluid sampling device into contact with a wall of the wellbore; means for withdrawing the first and the second fluid samples from the formation while; maintaining the inner probe at a first pressure; and maintaining the outer probe at a second pressure, wherein the first pressure is higher than the second pressure; means for determining a first contamination amount of the first fluid sample using an optical fluid analysis (OFA) sensor; means for determining a second contamination amount of the second fluid sample using the OFA sensor; and means for; determining in real-time a difference between the first and second contamination amounts; confirming correct operation of the fluid sampling device by determining in real-time a maximum of the difference between the first and second contamination amounts; extrapolating future values for the difference between the first and second contamination amounts by; normalizing the first and second contamination amounts using initial values of the first and second contamination amounts determined upon commencement of withdrawing the first and second fluid samples; and fitting to a power-law model the determined difference between the first and second contamination amounts; determining from the extrapolated future values a time at which the difference between the first and second contamination amounts will reach a minimum; continuing withdrawing of the first and second fluid samples until reaching the determined time; and
theninitiating collection of a portion of the first fluid sample.
Specification