Apparatus and methods for improved fluid displacement in subterranean formations

Abstract

Apparatus and methods for determining suitable displacement fluids for use in subterranean formations are provided. One example of a method is a method for identifying an inverter fluid to use for inverting an oleaginous-external/aqueous-internal fluid in a subterranean formation.

1 . A method of identifying an inverter fluid to use for inverting an oleaginous-external/aqueous-internal fluid in a subterranean formation, the method comprising: 
 measuring, at a temperature and pressure of about the pressure and temperature to which the inverter fluid will be exposed during placement in the formation, a value of a parameter related to the electrical conductivity of an initial composition that comprises: 
 a test fluid portion having a composition nominally equivalent to the oleaginous-external/aqueous-internal fluid; and  
 a portion of a selected inverter fluid; and  
   adding a further portion of the selected inverter fluid to the initial composition until the measured value of the parameter indicates that the mixture of the initial composition plus the added further portion of the selected inverter fluid has inverted from an oleaginous-external/aqueous-internal state to an aqueous-external/oleaginous-internal state.    
   
   
       2 . The method of  claim 1  further comprising determining a concentration of an inverter fluid ingredient used in the added further portion relative to the total volume of selected inverter fluid in the initial composition and added further portion of the selected inverter fluid.  
   
   
       3 . The method of  claim 1  further comprising determining the total volume of the selected inverter fluid in the initial composition and the added further part of the selected inverter fluid and determining the ratio of the determined total volume to the volume of test fluid in the initial composition.  
   
   
       4 . The method of  claim 1  further comprising making the initial composition, the making comprising mixing the test fluid and an aqueous-based fluid as the selected inverter fluid; and wherein the step of adding a further portion of the selected inverter fluid comprises injecting a selected surfactant in the initial composition.  
   
   
       5 . The method of  claim 1  further comprising making the initial composition, the making comprising mixing the test fluid, and a spacer fluid/ surfactant composition as the selected inverter fluid, in a selected ratio; and 
 wherein the step of adding a further portion of the selected inverter fluid includes injecting additional spacer fluid/surfactant composition in the initial composition.    
   
   
       6 . The method of  claim 1  wherein: 
 the measuring step further comprises elevating the pressure and temperature of the test fluid and the inverter fluid to a temperature and pressure of about a temperature and pressure to which the inverter fluid will be exposed in a subterranean formation; and    the adding step further comprises heating and stirring the initial composition.    
   
   
       7 . The method of  claim 6  further comprising determining a concentration of an inverter fluid ingredient used in the added further portion relative to the total of selected inverter fluid in the initial composition and added further portion of the selected inverter fluid.  
   
   
       8 . The method of  claim 6  further comprising determining the total volume of the selected inverter fluid in the initial composition and the added further portion of the selected inverter fluid and determining the ratio of the determined total volume to the volume of test fluid in the initial composition.  
   
   
       9 . The method of  claim 6  further comprising making the initial composition, the making comprising mixing the test fluid and an aqueous-based fluid as the selected inverter fluid; and wherein the step of adding a further portion of the selected inverter fluid comprises injecting a selected surfactant in the initial composition.  
   
   
       10 . The method of  claim 6  further comprising making the initial composition, the making comprising mixing the test fluid, and an aqueous-based fluid/ surfactant composition as the selected inverter fluid, in a selected ratio; and wherein the step of adding a further portion of the selected inverter fluid comprises injecting additional spacer fluid/surfactant composition in the initial composition.  
   
   
       11 . A method of identifying an inverter fluid to use for inverting an oleaginous-external/aqueous-internal fluid in a subterranean formation, the method comprising: 
 measuring, at a temperature and pressure of about the pressure and temperature to which the inverter fluid will be exposed during placement in the formation, a value of a parameter related to the electrical conductivity of an initial composition that comprises: 
 a test fluid portion having a composition nominally equivalent to the oleaginous-external/aqueous-internal fluid; and  
 a portion of a selected inverter fluid;  
   adding a further portion of the selected inverter fluid to the initial composition until the measured value of the parameter indicates that the mixture of the initial composition plus the added further portion of the selected inverter fluid has inverted from an oleaginous-external/aqueous-internal state to an aqueous-external/oleaginous-internal state; and    determining a concentration of an inverter fluid ingredient used in the added further portion relative to the total volume of selected inverter fluid in the initial composition and added further portion of the selected inverter fluid.    
   
   
       12 . The method of  claim 11  further comprising determining the total volume of the selected inverter fluid in the initial composition and the added further part of the selected inverter fluid and determining the ratio of the determined total volume to the volume of test fluid in the initial composition.  
   
   
       13 . The method of  claim 11  further comprising making the initial composition, the making comprising mixing the test fluid and an aqueous-based fluid as the selected inverter fluid; and wherein the step of adding a further portion of the selected inverter fluid comprises injecting a selected surfactant in the initial composition.  
   
   
       14 . The method of  claim 11  further comprising making the initial composition, the making comprising mixing the test fluid, and an aqueous-based fluid/ surfactant composition as the selected inverter fluid, in a selected ratio; and wherein the step of adding a further portion of the selected inverter fluid comprises injecting additional spacer fluid/surfactant composition in the initial composition.  
   
   
       15 . The method of  claim 11  further comprising making the initial composition, the making comprising mixing the test fluid, and a spacer fluid/ surfactant composition as the selected inverter fluid, in a selected ratio.  
   
   
       16 . The method of  claim 11  further comprising determining a concentration of an inverter fluid ingredient used in the added further portion relative to the total of selected inverter fluid in the initial composition and added further portion of the selected inverter fluid.  
   
   
       17 . A method of identifying an inverter fluid to use for inverting an oleaginous-external/aqueous-internal fluid in a subterranean formation, the method comprising: 
 providing an initial composition comprising a test fluid portion having a composition nominally equivalent to the oleaginous-external/aqueous-internal fluid and a portion of a selected inverter fluid, the providing comprising mixing the test fluid and the portion of the selected inverter fluid;    measuring, at a temperature and pressure of about the pressure and temperature to which the inverter fluid will be exposed during placement in the formation, a value of a parameter related to the electrical conductivity of the initial composition; and    adding a further portion of the selected inverter fluid to the initial composition until the measured value of the parameter indicates that the mixture of the initial composition plus the further portion of the selected inverter fluid has inverted from an oleaginous-external/aqueous-internal state to an aqueous-external/oleaginous-internal state.    
   
   
       18 . The method of  claim 17  further comprising determining a concentration of an inverter fluid ingredient used in the added further portion relative to the total volume of selected inverter fluid in the initial composition and added further portion of the selected inverter fluid.  
   
   
       19 . The method of  claim 17  further comprising determining the total volume of the selected inverter fluid in the initial composition and the added further part of the selected inverter fluid and determining the ratio of the determined total volume to the volume of test fluid in the initial composition.  
   
   
       20 . The method of  claim 17  wherein the measuring step further comprises elevating the pressure and temperature of the test fluid and the inverter fluid to a temperature and pressure of about a temperature and pressure to which the inverter fluid will be exposed in a subterranean formation; and 
 the adding step further comprises heating and stirring the initial composition.