Apparatus and methods to remove impurities at a sensor in a downhole tool
Apparatus and methods to remove impurities at a sensor in a downhole tool are disclosed. During the testing and/or sampling of formation fluid in a borehole, the downhole tool creates a transient high rate of fluid flow of the formation fluid to remove impurities at the sensor.
1. A method, comprising:
positioning a downhole tool in a wellbore penetrating a subterranean formation, wherein the downhole tool comprises:
a flow line;
a sensor in the flow line;
an inlet configured to communicate formation fluid to the sensor;
a chamber connected to the flow line and containing a cleaning fluid;
a first valve connecting the flow line to the chamber; and
a second valve connecting the chamber to the wellbore;
opening the first and second valves; and
flowing the cleaning fluid to the flow line to remove impurities at the sensor while withdrawing formation fluid from the formation.
2. A method as claimed in claim 1 , further comprising subjecting a piston in the chamber to fluid pressure from the wellbore to displace the cleaning fluid when the first and second valves are opened.
3. A method as claimed in claim 1 , wherein the downhole tool is configured to be used on a wire line.
4. A method as claimed in claim 1 , wherein the downhole tool is configured to be used on a drill string.