Mud Logging - Cutting sampling and description requirements

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This article describes the main geological services: Cutting sampling and description requirements.

Cuttings Sampling

Across reservoir: every 5 ft, and non-reservoir every 20 ft.

Cutting samples shall be taken from the full width of the shakers so as to be representative of the interval drilled. When drilling at high ROP the drilling contractor shall assign a roughneck as a sample catcher.

Cuttings Description

Lithological analysis of the cuttings shall be performed on the washed samples with the aid of a reflected light microscope. Fluoroscopic analysis shall be carried out on all samples. Any samples indicating fluorescence shall be treated with solvents to detect hydrocarbons and establish the nature of the cut.

Cuttings Handling

Washed samples shall be dried and packed in envelopes marked with the date, well number and depth. Wet unwashed samples shall be put into sample bags lined with a plastic bag at the time of collection at the shakers. Samples for geochemical analysis if required shall be packed in tins topped up with potable water. Bactericide shall be added before sealing the tin.

Depth Correction

Cutting lag time shall be known at all times. A carbide lag time test shall be performed every 12 hours or every 500 ft whilst drilling (especially in washed out N.Umer interval). The Driller and Drilling Supervisor shall be informed before performing a lag test.

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