Apparatus and method of coring

Abstract

An apparatus and method for obtaining core samples from a wellbore includes bringing a substance in contact with the core sample. The substance is adapted to retain at least a portion of fluids recovered with the core sample. A receptacle such as a core barrel contains the substance and is inserted into the wellbore and receiving the core sample in the receptacle. The substance may be sealed in the receptacle by a dissolvable plug mechanism. The substance is transformable between a highly viscous state and a substantially solid matrix.

What is claimed is:  
     
         1 . A method for obtaining core samples from a wellbore, comprising the steps of: 
 obtaining a core sample from the wellbore; and    bringing a substance into contact with the core sample, the substance being adapted to retain at least a portion of fluids recovered with the core sample.    
     
     
         2 . A method according to  claim 1 , further comprising the steps of inserting a receptacle into the wellbore and receiving the core sample in the receptacle  
     
     
         3 . A method according to  claim 2 , wherein the substance is contained in the receptacle.  
     
     
         4 . A method according to  claim 3 , wherein substance is sealed in the receptacle by a plug mechanism.  
     
     
         5 . A method according to  claim 4 , further comprising the step of removing the plug mechanism after inserting the receptacle into the wellbore.  
     
     
         6 . A method according to  claim 1 , wherein the substance is less dense than drilling mud.  
     
     
         7 . A method according to  claim 1  wherein the substance is miscible with the fluids.  
     
     
         8 . A method according to  claim 1  wherein the substance undergoes a chemical reaction with the fluids.  
     
     
         9 . A method according to  claim 1 , wherein the substance is transformable between a highly viscous state and a substantially solid matrix.  
     
     
         10 . A method according to  claim 1 , wherein the substance is adapted to retain oil.  
     
     
         11 . A method according to  claim 1 , wherein the fluids are subsequently recoverable from the substance adapted to retain the fluids.  
     
     
         12 . A method according to  claim 1 , wherein the substance is a polymeric mixture.  
     
     
         13 . A method according to  claim 12 , wherein the polymeric mixture comprises a first polymeric material and a second polymeric material.  
     
     
         14 . A method according to  claim 13 , wherein the first polymeric material comprises a compound of general formula  
       
         
           
           
               
               
           
         
       
       or a salt thereof where A and B are the same or different and at least one comprises a relatively polar atom or group and R 1  and R 2  independently comprise relatively non-polar atoms or groups.  
     
     
         15 . A method according to  claim 14 , wherein the first polymeric material is dissolved in a generally hydrophillic solvent whereby the C═C groups react with one another to form a polymeric material.  
     
     
         16 . A method according to  claim 13 , wherein the first polymeric material is poly(1,4-di(4-(N-methylpyridinyl))-2,3-di(4-(1-formylphenyl) butylidene.  
     
     
         17 . A method according to  claim 13 , wherein the second polymeric material is polyvinyl alcohol.  
     
     
         18 . A method according to  claim 15 , wherein the solvent consists substantially of water.  
     
     
         19 . A method according to  claim 13 , wherein the addition of the second polymeric material to the first polymeric material causes the substance to form one of a gel and a colloid.  
     
     
         20 . A method according to  claim 19 , wherein the first and second polymeric materials in the substance react with one another, said reaction being catalysed by an acid.  
     
     
         21 . A method according to  claim 20 , comprising the step of controlling the rate of reaction of the first and second polymeric materials by controlling the concentration of acid to catalyse the rate of the formation of the gel/colloid.  
     
     
         22 . A method according to  claim 13 , wherein the percent weight of the first polymeric material to that of the second polymeric material is in the range of approximately 0.3 to 20.  
     
     
         23 . A method according to  claim 20 , wherein the polymeric mixture is added to a solvent, and thereafter the polymeric mixture is then added to the receptacle and thereafter an acid is added to catalyse the reaction between the first and second polymeric materials.  
     
     
         24 . A method of obtaining a sample of a formation from a borehole comprising the steps of: 
 filling a portion of the borehole with a substance adapted to change state so as to absorb or trap fluids;    allowing the substance to absorb or trap fluids; and    removing said substance with absorbed or trapped fluids from the borehole.    
     
     
         25 . An apparatus for obtaining core samples from a wellbore, the apparatus comprising a receptacle for obtaining a core sample and a substance adapted to retain at least a portion of fluids recovered with the core sample.  
     
     
         26 . An apparatus according to  claim 25 , wherein the receptacle is a core barrel and is connected to an elongate member capable of being lowered into and raised from the wellbore.  
     
     
         27 . An apparatus according to  claim 26 , wherein the core barrel is connected to a tubular string and the core barrel engages the wellbore to remove the core sample.  
     
     
         28 . An apparatus according to  claim 26 , wherein the core barrel is substantially filled to capacity with the substance.  
     
     
         29 . An apparatus according to  claim 26 , wherein a plug mechanism is provided to seal the core barrel.  
     
     
         30 . An apparatus according to  claim 29 , wherein the plug mechanism is adapted to dissipate in a pre-determined manner.  
     
     
         31 . The use of a substance to stabilise a core sample recovered from a wellbore, the substance being transformable between a highly viscous state and a substantially solid matrix.  
     
     
         32 . A substance for stabilising a core sample recovered from a wellbore, the substance being transformable between a highly viscous state and a substantially solid matrix.  
     
     
         33 . A wellbore core sample stabilising device comprising a substance which is transformable between a highly viscous state and a substantially solid matrix.