Drilling fluid additive and method

Abstract

A method is provided for drilling a wellbore including the steps of: providing a drilling mud comprising a primary amine; circulating the drilling mud while the wellbore is being drilled wherein the primary amine is incorporated into a filter cake deposited on the wellbore wall as the wellbore is being drilled; and removing at least a portion of the filter cake after the wellbore is drilled by circulating fluid into the wellbore a composition comprising nitrous acid. The invention also includes the drilling fluid containing a solid component that generates gas from within the filter cake upon contact with a component that causes the solid component to generate gas. In some embodiments, the solid component is a primary amine grafted to a polymer that is not soluble in the drilling fluid composition such as a starch.

1 . A method for drilling a wellbore comprising the steps of: 
 providing a drilling mud comprising a primary amine;    circulating the drilling mud while the wellbore is being drilled wherein the primary amine is incorporated into a filter cake deposited on the wellbore wall as the wellbore is being drilled; and    removing at least a portion of the filter cake after the wellbore is drilled by circulating fluid into the wellbore comprising nitrous acid.    
   
   
       2 . The method of  claim 1  wherein the primary amine is grafted to a starch.  
   
   
       3 . The method of  claim 1  wherein the primary amine is grafted to a xanthan gum.  
   
   
       4 . The method of  claim 1  wherein the primary amine is grafted to a polymer that is not soluble in the drilling fluid composition.  
   
   
       5 . The method of  claim 4  wherein the amount of the primary amine in the drilling mud results in the drilling fluid containing between about 0.5 and about 3 percent by weight nitrogen.  
   
   
       6 . The method of  claim 5  wherein the amount of the primary amine in the drilling mud results in the drilling fluid containing between about 0.1 and about 10 percent by weight nitrogen.  
   
   
       7 . The method of  claim 1  wherein the drilling mud comprising the primary amine is circulated while the wellbore is being drilled through at least a part of a production interval.  
   
   
       8 . The method of  claim 1  wherein the at least a portion of the filter cake is removed by circulating fluid into the wellbore having a pH of between about 1 and about 3.  
   
   
       9 . The method of  claim 1  wherein the fluid has a pH of less than about 4 further comprises a product of nitrite salt and a mineral acid.  
   
   
       10 . The method of  claim 8  wherein the nitrite salt comprises sodium nitrite.  
   
   
       11 . The method of  claim 1  wherein the filter cake is at least partially removed by formation of vapour nitrogen within the filter cake.  
   
   
       12 . A drilling fluid comprising between about 0.5 and about 3 percent by weight of nitrogen in the form of a primary amine.  
   
   
       13 . The drilling fluid of  claim 12  further comprising between about 1 and about 10 percent by weight of a starch.  
   
   
       14 . The drilling fluid of  claim 13  wherein at least a portion of the primary amine is grafted onto the starch.  
   
   
       15 . The drilling fluid of  claim 12  wherein at least a portion of the primary amine is grafted onto xanthan gum.  
   
   
       16 . The drilling fluid of  claim 12  wherein the primary amine is grafted to a polymer that is not soluble in the drilling fluid.  
   
   
       17 . The drilling fluid of  claim 12  wherein the drilling fluid is a water based drilling fluid.  
   
   
       18 . The drilling fluid of  claim 12  wherein the primary amine is an aliphatic amine.  
   
   
       19 . The drilling fluid of  claim 12  further comprising a bentonite clay.  
   
   
       20 . The drilling fluid of  claim 12  wherein the drilling fluid further comprises sodium chloride.  
   
   
       21 . A method of providing a wellbore in a hydrocarbon production zone comprising the steps of: 
 incorporating into a drilling fluid a solid component that forms a gas when exposed to an activating component;    circulating the drilling fluid while drilling the wellbore in the hydrocarbon production zone whereby the solid component; and    circulating a drilling fluid comprising the activating component after at least a portion of the wellbore within the production zone is drilled, and there by forming gas bubbles within the filter cake and causing the filter cake to at least partially release from a wall of the wellbore.    
   
   
       22 . The method of  claim 21  wherein the solid component is a primary amine.  
   
   
       23 . The method of  claim 22  wherein the primary amine is grafted onto a starch.  
   
   
       24 . The method of  claim 22  wherein the primary amine is grafted onto a xanthan gum.  
   
   
       25 . The method of  claim 22  wherein the primary amine is grafted onto a polymer that is not soluble in the drilling fluid.  
   
   
       26 . The method of  claim 22  wherein the activating component is an acid.  
   
   
       27 . The method of  claim 26  wherein the activation component further comprises nitrous acid.  
   
   
       28 . The method of  claim 21  wherein the primary amine is a polyvinyl amine.  
   
   
       29 . The method of  claim 21  further comprising the step of placing a screen in the wellbore after the wellbore is drilled and prior to circulating the drilling fluid comprising the activating component.  
   
   
       30 . The method of  claim 21  wherein the gas bubbles are nitrogen gas bubbles.