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 H 2 S, 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 H 2 S, mercaptan, and mercury retention of greater than about 95% of the original concentration in samples stored up to 14 days.

1 . A well fluid sampling apparatus, the apparatus comprising:
 a sample chamber for receiving and holding a sample well fluid; and   a diamond-like carbon coating provided on an interior of the sample chamber, that substantially prevents absorption of at least one of H 2 S, mercury, and a mercaptan therethrough.   
   
   
       2 . The well fluid sampling apparatus of  claim 1 , wherein the coating is a dense, amorphous, diamond-like carbon, with an sp3 content greater than about 65%. 
   
   
       3 . The well fluid sampling apparatus of  claim 1 , wherein the coating composition comprises about 70 percent (%) carbon and about 30 percent (%) hydrogen. 
   
   
       4 . The well fluid sampling apparatus of  claim 1 , wherein the thickness of the coating is no more than about 20 microns. 
   
   
       5 . The well fluid sampling apparatus of  claim 1 , wherein the thickness of the coating is between about 10 and about 15 microns. 
   
   
       6 . The well fluid sampling apparatus of  claim 1 , wherein the diamond-like coating includes a first layer that overlies a surface of the sample chamber, and a second layer that overlies the first layer and defines an interior surface of the sample chamber. 
   
   
       7 . The well fluid sampling apparatus of  claim 6 , wherein the coating further includes a third layer between said first and second layers of diamond-like coating to increase adhesion between the first and second layers. 
   
   
       8 . The well fluid sampling apparatus of  claim 6 , wherein the first layer of diamond-like coating includes silicon to promote adhesion to a metal surface of the sampler. 
   
   
       9 . The well fluid sampling apparatus of  claim 6 , wherein the second layer of diamond-like coating includes silicon to render it more inert to absorption of at least one of H 2 S, mercury, and a mercaptan therethrough. 
   
   
       10 . A well fluid sampling apparatus, the apparatus comprising:
 a sample chamber for receiving and holding a sample well fluid; and   a diamond-like carbon coating provided on an interior of the sample chamber and that substantially prevents absorption of at least one of H 2 S, mercury, and a mercaptan therethrough,   wherein the coating is a dense, amorphous, diamond-like carbon with an sp3 content greater than about 65% and having a composition comprising about 70 percent (%) carbon and about 30 percent (%) hydrogen.   
   
   
       11 . The well fluid sampling apparatus of  claim 10 , wherein the thickness of the coating is no more than about 20 microns. 
   
   
       12 . The well fluid sampling apparatus of  claim 10 , wherein the thickness of the coating is no more than about 15 microns. 
   
   
       13 . The well fluid sampling apparatus of  claim 10 , wherein the diamond-like coating includes a first layer that overlies a metal surface of the sample chamber, and a second layer that overlies the first layer and defines an interior surface of the sample chamber, and wherein said first layer includes silicon to increase adherence between the metal surface of the sample chamber and the coating. 
   
   
       14 . The well fluid sampling apparatus of  claim 13 , wherein the second layer of diamond-like coating also includes silicon to render it more inert to absorption of at least one of H 2 S, mercury, and a mercaptan therethrough. 
   
   
       15 . The well fluid sampling apparatus of  claim 13 , wherein the coating further includes a third layer between said first and second layers of diamond-like coating to increase adhesion between the first and second layers. 
   
   
       16 . A method of rendering an interior surface of a sample chamber of a well fluid sampling apparatus substantially impervious to absorption of at least one of H 2 S, mercury, and a mercaptan, comprising
 applying a diamond-like carbon coating over said interior surface of the sample chamber.   
   
   
       17 . The method of  claim 16 , wherein the diamond-like carbon coating is applied over said surface by one of a plasma assisted chemical vapor deposition process or a PAVCD process. 
   
   
       18 . The method of  claim 16 , wherein the coating is a dense, amorphous, diamond-like carbon with an sp3 content greater than about 65% and having a composition comprising about 70 percent (%) carbon, about 30 percent (%) hydrogen. 
   
   
       19 . The method of  claim 16 , wherein said application step includes applying a first layer of diamond-like carbon coating over the interior surface of the vessel, and then applying a second layer of diamond-like carbon coating over the first layer. 
   
   
       20 . The method of  claim 19 , further including the step of applying an intermediate layer of diamond-like carbon coating between said first and second layers to increase adherence therebetween. 
   
   
       21 . The method of  claim 17 , wherein said coating is applied to a thickness of between about 10 and about 20 microns. 
   
   
       22 . The method of  claim 17 , wherein said coating is applied to a thickness of between about 10 and about 15 microns.