Sampling device with diamond-like carbon coating

Abstract

A diamond-like carbon coating is provided on a metal interior surface of a sample chamber of a well fluid sampling apparatus to render the sample chamber substantially impervious to the absorption of at least H₂S, mercury, and/or mercaptans. The coating is a dense, amorphous, diamond-like carbon with an sp3 content greater than about 65% and is composed of about 70 percent (%) carbon, 30 percent (%) hydrogen. The coating may be applied over the surface in one or more layers by a suitable method, e.g., plasma assisted chemical vapor deposition or a PAVCD process, and is between about 10 and about 20 microns thick. One or more of the layers of the coating includes a small percentage of silicon to increase both the adherence to the metal interior surface of the sample chamber and the absorption resistance of the coating. The resulting sample chamber provides H₂S, mercaptan, and mercury retention of greater than about 95% of the original concentration in samples stored up to 14 days.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is related to and claims the benefit of U.S. Provisional Patent Application 61 / 104,116, filed on Oct. 9, 2008, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention generally relates to sampling devices for oilfield reservoir fluids that allow sampling and measurement of trace amounts of H2S, and is specifically concerned with a diamond-like carbon coating applied over the internal surfaces of the sampling chamber of such devices that renders the chamber substantially impermeable (or non absorbent) to H2Sand able to withstand acid and alkaline fluids.[0004]2. Discussion of the Background[0005]Existing sampling technology preserves samples above reservoir pressure ensuring representative pressure / volume / temperature (PVT) analysis. However, for chemical or trace element analysis some components of the samples are lost due to ph...

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Benefits of technology

[0009]Therefore, there is a need to develop sampling devices that can be used to sample oilfield fluids that have traces of H2S and are able to measure the H2S. There is further a need to develop a sampling device having an internal coating that can withstand alkaline chemical environment and that also has superior mechanical wear resistance. To these ends, the present invention provides a well fluid sampling device (or tool) including a sample chamber for receiving and holding a sample well fluid that has been coated with a diamond-like coating (DLC). The coating employed in the inventive sampling dev

Problems solved by technology

However, for chemical or trace element analysis some components of the samples are lost due to physical or chemical processes, most of which are time dependent.

Many of the components will react with the walls of sampling tools/sample bottles and/or decompose with time.

However, all such c

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