Dispersive riserless drilling fluid

Abstract

A method for drilling riserless that includes providing a drilling fluid to a drilling assembly for drilling a borehole on a seafloor, the drilling assembly comprising a drill string and a bottomhole assembly, and wherein the drilling fluid includes a brine, and a non-hydratable clay, wherein the drilling fluid is substantially free of hydrating clays, and flowing the drilling fluid and cuttings through an annulus formed by the drill string and the borehole into sea water is disclosed.

1 . A method for drilling riserless, comprising:
 providing a drilling fluid to a drilling assembly for drilling a borehole on a seafloor, the drilling assembly comprising a drill string and a bottomhole assembly, and wherein the drilling fluid comprises:
 a brine; and 
 a non-hydratable clay, wherein the drilling fluid is substantially free of hydrating clays; and 
   flowing the drilling fluid and cuttings through an annulus formed by the drill string and the borehole into sea water.   
   
   
       2 . The method of  claim 1 , further comprising:
 inserting a casing into the borehole.   
   
   
       3 . The method of  claim 2 , wherein the casing is inserted in the borehole as the borehole is drilled. 
   
   
       4 . The method of  claim 2 , wherein the casing is inserted in the borehole after the borehole is drilled. 
   
   
       5 . The method of  claim 1 , wherein the non-hydratable clay comprises at least one of attapulgite and sepiolite clays. 
   
   
       6 . The method of  claim 1 , wherein the drilling fluid ranges from about 9.0 to 14 ppg. 
   
   
       7 . The method of  claim 1 , wherein the drilling fluid has a pH ranging from about 7.5 to 12. 
   
   
       8 . The method of  claim 1 , wherein the drilling fluid further comprises at least one of a weighting agent, a deflocculant, a fluid loss control agent, and combinations thereof. 
   
   
       9 . The method of  claim 1 , wherein the drilling fluid further comprises a salt of an alkali metal or alkaline earth metal. 
   
   
       10 . A method of drilling a formation, comprising:
 providing a drilling fluid to a drilling assembly for drilling a borehole on a seafloor, the drilling assembly comprising a drill string and a bottomhole assembly, and wherein the drilling fluid comprises:
 a brine; 
 attapulgite clay; and 
 a salt of an alkali metal or alkaline earth metal, wherein the mud is substantially free of hydrating clays; and 
   flowing the drilling fluid and cuttings through an annulus formed by the drill string and the borehole into sea water.   
   
   
       11 . The method of  claim 10 , wherein the drilling fluid ranges from about 9.0 to 14 ppg. 
   
   
       12 . The method of  claim 10 , wherein the drilling fluid has a pH ranging from about 7 to 12. 
   
   
       13 . The method of  claim 10 , wherein the drilling fluid further comprises at least one of a weighting agent, a deflocculant, a fluid loss control agent, and combinations thereof. 
   
   
       14 . A wellbore fluids comprising:
 an aqueous fluid;   attapulgite clay; and   a salt of an alkali metal or alkaline earth metal, wherein the wellbore fluid is substantially free of hydrating clays.   
   
   
       15 . The wellbore fluid of  claim 14 , wherein the non-hydratable clay comprises at least one of attapulgite and sepiolite clays. 
   
   
       16 . The wellbore fluid of  claim 14 , wherein the drilling fluid ranges from about 9.0 to 14 ppg. 
   
   
       17 . The wellbore fluid of  claim 14 , wherein the drilling fluid has a pH ranging from about 7 to 12. 
   
   
       18 . The wellbore fluid of  claim 14 , further comprising:
 at least one of a weighting agent, a deflocculant, and combinations thereof.