System and method for reducing and managing surface pressure of casing strings

Abstract

A method involves reducing pressure in casing strings. Such method includes bleeding off a volume of annuli fluid from a casing string of a well. The method further includes injecting a first brine into the casing string to establish an initial injectivity into a micro-annulus of the casing string.

What is claimed is: 
     
         1 . A method for reducing surface pressure of casing strings, comprising:
 bleeding off a volume of annuli fluid from a casing string of a well; and   subsequently injecting a first brine into the casing string.   
     
     
         2 . The method of  claim 1 , comprising iteratively bleeding off and injecting additional amounts of the first brine into the casing string until a target pressure is reached. 
     
     
         3 . The method of  claim 2 , wherein the target pressure is below a maximum allowed working operation pressure (MAWOP). 
     
     
         4 . The method of  claim 2 , comprising automatically shutting off a pump via a pressure switch in response to detecting that a pressure threshold is reached. 
     
     
         5 . The method of  claim 1 , comprising injecting a second brine that is denser than the first brine into the casing string following a subsequent bleeding off of annuli fluid in response to detecting that a stable surface pressure using the first brine exceeds a target pressure threshold. 
     
     
         6 . The method of  claim 5 , wherein the second brine comprises sodium bromide, potassium bromide, zinc bromide, or mixtures thereof. 
     
     
         7 . The method of  claim 1 , wherein the first brine comprises sodium chloride, potassium chloride, zinc chloride, sodium bromide, potassium bromide, zinc bromide, or mixtures thereof. 
     
     
         8 . The method of  claim 1 , wherein bleeding off the volume of the annuli fluid comprises iteratively bleeding off the annuli fluid volumes until a target lower pressure is reached. 
     
     
         9 . The method of  claim 1 , wherein the first brine has a density at room temperature of from 1.1 to 2.0 g·cm −3 , and the second brine has a density at room temperature from 1.3 to 3.0 g·cm −3 . 
     
     
         10 . The method  claim 1 , further comprising, before bleeding off a volume of annuli fluid, detecting an elevated surface pressure of the casing strings. 
     
     
         11 . A well system, comprising:
 a supply tank comprising a brine;   a pump fluidically coupled to the supply tank and a casing string of a well; and   a pressure switch fluidically coupled to the pump, wherein the pressure switch is to switch off the pump in response to detecting that a surface pressure at the casing string of the well has exceeded a threshold surface pressure.   
     
     
         12 . The well system of  claim 11 , wherein the brine comprises an inhibited brine that is treated with corrosion mitigation and oxygen scavenger chemicals. 
     
     
         13 . The well system of  claim 11 , wherein the brine comprises sodium chloride. 
     
     
         14 . The well system of  claim 13 , wherein the sodium chloride comprises a solution in the range of 10 pound per gallon (lb/gal) or 1.2 gram per cubic centimeter (gm/cc) sodium chloride. 
     
     
         15 . The well system  claim 11 , wherein the brine comprises sodium bromide. 
     
     
         16 . The well system of  claim 15 , wherein the sodium bromide comprises a solution within the range of 12.5 pound per gallon (lb/gal) or 1.5 gram per cubic centimeter (gm/cc) sodium bromide. 
     
     
         17 . The well system of  claim 11 , comprising a manifold to couple the pump to the casing string of the well. 
     
     
         18 . The well system of  claim 11 , comprising a manifold to couple the pump to a plurality of wells. 
     
     
         19 . The well system of  claim 11 , wherein the pump comprises a high pressure, low volume pump. 
     
     
         20 . The well system of  claim 11 , wherein the pump is solar powered. 
     
     
         21 . The well system of  claim 11 , wherein the well comprises a micro-annulus associated with a higher pressure in the casing string in the well.