Cross quality control of mud logging measurements
AssigneeSchlumberger Technology Corporation
InventorsNicholas Abolins, Pierrick Ferrando
Life of this patent
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Abstract
A method for mud logging includes making first gas measurements of a first gas sample obtained from circulating drilling fluid on a drill rig using a first gas chain; making second gas measurements of a second gas sample obtained from circulating drilling fluid on a drill rig using a second gas chain; defining a quality control window for the first gas measurements from the second gas measurements; and cross quality controlling the first and second gas measurements by comparing the first gas measurements with the quality control window.
Claims20
A method for mud logging comprising:
- making first gas measurements of a first gas sample obtained from a circulating drilling fluid flowing through a fluid conduit on a drill rig using a first gas chain comprising a first degasser disposed at the fluid conduit extending between a wellbore and a mud pit;
- simultaneous to the making the first gas measurements of the first gas sample, making second gas measurements of a second gas sample obtained from the circulating drilling fluid on the drill rig using a second gas chain comprising a second degasser disposed at the fluid conduit between the wellbore and the mud pit;
- defining a quality control window for the first gas measurements from the second gas measurements;
- and
- cross quality controlling the first gas measurements and the second gas measurements by comparing the first gas measurements with the quality control window.
A system for assessing downhole gas composition measurements, the system comprising:
- a first degasser configured to obtain a first gas sample from a circulating drilling fluid flowing through a fluid conduit extending between a wellbore and a mud pit;
- a second degasser disposed at the fluid conduit between the wellbore and the mud pit, the second degasser configured to obtain a second gas sample from the circulating drilling fluid;
- a first gas measurement device configured to make a first gas measurement of a composition of the first gas sample;
- a second gas measurement device configured to make a second gas measurement of a composition of the second gas sample;
- and
- a processor configured to:
- receive the first gas measurement and the second gas measurement;
- define a quality control window for the first gas measurement from the second gas measurement;
- and
- cross quality control the first gas measurement and the second gas measurement by comparing the first gas measurement with the quality control window.
A method for mud logging comprising:
- obtaining a first gas sample from a circulating drilling fluid flowing through a fluid conduit using a first degasser and a second gas sample from the circulating drilling fluid flowing through the fluid conduit using a second degasser independent of the first degasser while drilling a subterranean wellbore, wherein:
- the first degasser is disposed on the fluid conduit extending between a wellbore and a mud pit;
- and
- the first degasser comprises a first type of degasser including a vacuum degasser and the second degasser comprises a second type of degasser different than the first type of degasser, the second type of degasser including at least one of a centrifugal degasser or an impeller degasser;
- making a first gas measurement corresponding to the first gas sample using a first gas analyzer and a second gas measurement corresponding to the second gas sample using a second gas analyzer independent of the first gas analyzer;
- determining an expected ratio of the first gas measurement and the second gas measurement;
- determining first cross quality control limits and second cross quality control limits based on the expected ratio to define a quality control window;
- and
- cross quality controlling the first gas measurement and the second gas measurement by comparing the first gas measurement with the quality control window.
Dependencies are inferred from the claim text.