Method for separating drill fluid from oily drill cuttings slurries

Abstract

The present invention provides a method for separating oily drill fluid from an oily drill cuttings slurry comprising oily drill fluid and drill cuttings. The method comprises destructively modifying at least a portion of the drill cuttings that are contacted by at least one cuttings-reactive chemical thereby disrupting attraction forces between the portion of the drill cuttings and the oily drill fluid and making it easier for mechanical cuttings treatment equipment to separate oily drill fluid from the oily drill cuttings slurry.

1 . A method for separating oily drill fluid from an oily drill cuttings slurry comprising oily drill fluid and drill cuttings, the method comprising:
 a) mixing at least one liquid additive solution comprising at least one cuttings-reactive chemical with at least a portion of the oily drill cuttings slurry thereby creating a chemically-treated cuttings slurry wherein at least one cuttings-reactive chemical contacts and reacts with at least a portion of the drill cuttings; and   b) destructively modifying at least a portion of the drill cuttings that are contacted by at least one cuttings-reactive chemical thereby disrupting attraction forces between the portion of the drill cuttings and the oily drill fluid.   
     
     
         2 . A method for separating oily drill fluid from an oily drill cuttings slurry comprising oily drill fluid and drill cuttings, the method comprising:
 a) mixing at least one liquid additive solution comprising at least one cuttings-reactive chemical with at least a portion of the oily drill cuttings slurry thereby creating a chemically-treated cuttings slurry wherein at least one cuttings-reactive chemical contacts and reacts with at least a portion of the drill cuttings; and   b) destructively modifying at least a portion of the drill cuttings that are contacted by at least one cuttings-reactive chemical thereby disrupting attraction forces between the portion of the drill cuttings and the oily drill fluid; and   c) moving at least a portion of the chemically treated cuttings slurry into mechanical cuttings treatment equipment (MCTE) selected from the group consisting of: a settling tank, a mixing tank, a heating tank, an oven, a conveyor, a sieve, a screen, a filter, a vibrator, a shaker, a shale shaker, a cuttings dryer, a centrifuge, a hydrocyclone and combinations thereof; and   d) removing at least a portion of the separated oily drill fluid from the MCTE.   
     
     
         3 . A method for separating oily drill fluid from an oily drill cuttings slurry comprising oily drill fluid and drill cuttings, the method comprising:
 a) placing the oily drill cuttings slurry into mechanical cuttings treatment equipment (MCTE) selected from the group consisting of: a settling tank, a mixing tank, a heating tank, an oven, a conveyor, a sieve, a screen, a filter, a vibrator, a shaker, a shale shaker, a cuttings dryer, a centrifuge, a hydrocyclone, and combinations thereof, and operating said MCTE to produce at least one mechanically treated cuttings slurry comprising oily drill fluid and drill cuttings; and   b) mixing at least one liquid additive solution comprising at least one cuttings-reactive chemical with at least a portion of the at least one mechanically treated cuttings slurry thereby creating a chemically treated cuttings slurry wherein at least one cuttings-reactive chemical contacts and reacts with at least a portion of the drill cuttings; and   c) destructively modifying at least a portion of the drill cuttings that are contacted by at least one cuttings-reactive chemical thereby disrupting attraction forces between the portion of the drill cuttings and the oily drill fluid; and   d) moving at least a portion of the chemically treated cuttings slurry into MCTE wherein the MCTE separates at least a portion of the oily drill fluid from at least a portion of the chemically treated cuttings slurry; and   e) removing at least a portion of the separated oily drill fluid from the MCTE.   
     
     
         4 . A method for separating oily drill fluid and barite from an oily drill cuttings slurry comprising oily drill fluid and drill cuttings and barite, the method comprising:
 a) placing the oily drill cuttings slurry into mechanical cuttings treatment equipment (MCTE) selected from the group consisting of: a settling tank, a mixing tank, a heating tank, an oven, a conveyor, a sieve, a screen, a filter, a vibrator, a shaker, a shale shaker, a cuttings dryer, a centrifuge, a hydrocyclone, and combinations thereof, and operating said MCTE to produce at least one mechanically treated cuttings slurry comprising oily drill fluid and drill cuttings and barite; and   b) mixing at least one liquid additive solution comprising at least one cuttings-reactive chemical with at least a portion of the at least one mechanically treated cuttings slurry thereby creating a chemically treated cuttings slurry wherein at least one cuttings-reactive chemical contacts and reacts with at least a portion of the drill cuttings; and   c) destructively modifying at least a portion of the drill cuttings that are contacted by at least one cuttings-reactive chemical thereby disrupting attraction forces between the portion of the drill cuttings and the oily drill fluid and creating a barite enhanced cuttings slurry in which the solids weight percent of barite has increased; and   d) moving at least a portion of the barite-enhanced cuttings slurry into MCTE wherein the MCTE separates at least a portion of the oily drill fluid and barite from at least a portion of the barite-enhanced cuttings slurry; and   e) removing at least a portion of the separated oily drill fluid and barite from the MCTE.   
     
     
         5 . The method as claimed in  claim 1  wherein the drill cuttings comprise between 10 and 99 wt % silicate minerals. 
     
     
         6 . The method as claimed in  claim 1  wherein the at least one cuttings-reactive chemical is selected from the group consisting of hydrogen fluoride, hydrogen chloride, hydrogen bromide, ammonium fluoride, ammonium bifluoride, carboxylic acid, a chelation agent and combinations thereof. 
     
     
         7 . The method as claimed in  claim 1  wherein the at least one cuttings-reactive chemical is selected from the group consisting of ammonium fluoride, ammonium bifluoride, barium fluoride, calcium fluoride, sodium fluoride, potassium fluoride, potassium bifluoride, fluoroboric acid, fluorosulfuric acid, antimony pentafluoride, hydrochloric acid, hydrofluoric acid, hexafluosilicic acid, phosphoric acid, hydrobromic acid, phosphonic acid, sulfuric acid, nitric acid, citric acid, carboxylic acid, a chelation agent and combinations thereof. 
     
     
         8 . The method as claimed in  claim 6  wherein the chelation agent comprises one or more chemical substances selected from the group consisting of NN-hydroxyethyliminodiacetate (HEIDA), diethylenetriaminepentacetic acid (DPTA), ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), L-glutamic acid NN-diacetic acid (GLDA), hydroxy ethylethylenediaminetetraacetic acid (HEDTA) and combinations thereof. 
     
     
         9 . The method as claimed in  claim 1  wherein the at least one liquid additive solution comprises a liquid selected from the group consisting of water; methanol, ethanol, ethylene glycol and combinations thereof. 
     
     
         10 . The method as claimed in  claim 1  further comprising mixing at least one first reactant with a liquid solution comprising at least one second reactant selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, phosphonic acid, carboxylic acid and combinations thereof thereby creating the at least one cuttings-reactive chemical. 
     
     
         11 . The method as claimed in  claim 10  wherein the at least one first reactant comprises one or more chemical substances selected from the group consisting of sodium fluoride, sodium bifluoride, calcium fluoride, aluminium fluoride, ammonium fluoride, ammonium bifluoride, ammonium borofluoride, barium fluoride, potassium fluoride, potassium bifluoride, sodium monofluorophosphate, apatite, cryolite and combinations thereof. 
     
     
         12 . The method as claimed in  claim 10  wherein the at least one first reactant selected from the group consisting of ammonium fluoride, sodium fluoride, calcium fluoride, barium fluoride and combinations thereof. 
     
     
         13 . The method as claimed in  claim 1  further comprising mixing at least one first reactant that comprises barium fluoride with a liquid solution comprising at least one second reactant that comprises sulfuric acid, thereby creating, upon mixing said first and second reactants, barite and at least one cuttings-reactive chemical. 
     
     
         14 . The method as claimed in  claim 13  further comprising recovering from drill cuttings slurry at least a portion of the created barite. 
     
     
         15 . The method as claimed in  claim 1  wherein the at least one cuttings-reactive chemical comprises sodium hydroxide or potassium hydroxide or sodium carbonate or potassium carbonate or sodium bicarbonate or combinations thereof.