Microencapsulated Acid with Perforation Strategies to Improve the Delivery and Treatment of Formations in Hydraulic Fracturing Applications

Abstract

Acid plays an important role in the hydraulic fracturing process, such as removing damage from the cement and formation which can result from perforating operations, thus providing a better path for the fracturing operations that follow. The disclosure relates generally to microencapsulated acid or acid precursor for targeted delivery and dosing of acid at the site of perforation in hydraulic fracturing applications, device and method of use the same. The targeted delivery and dosing of acid at the site of perforation provides the benefit of, including but not limited to, eliminating over acidizing (limiting near wellbore formation damage) and optimizing the removal of perforation residue and formation materials for lowering break-down pressure.

What is claimed is: 
     
         1 . A perforation gun assembly, comprising:
 an acid payload chamber and a perforating gun payload chamber, or   a chamber containing both an acid payload and a perforating gun payload.   
     
     
         2 . The perforation gun assembly of  claim 1 , wherein the acid payload chamber or the chamber containing both an acid payload and a perforating gun payload contains a microencapsulated acid. 
     
     
         3 . The perforation gun assembly of  claim 1 , further comprising an overbalance payload chamber, wherein the overbalance payload chamber contains propellant or similar material, and can be activated to create a transient overbalance condition. 
     
     
         4 . The perforation gun assembly of  claim 1 , wherein the acid payload comprises microencapsulated acid particulates with a polymeric shell and an acid or acid precursor core. 
     
     
         5 . The perforation gun assembly of  claim 1 , further comprising an acid payload chamber and a perforating gun payload chamber, wherein the acid payload comprises microencapsulated acid particulates with a polymeric shell and an acid or acid precursor core. 
     
     
         6 . The perforation gun assembly of  claim 5 , further comprising an overbalance payload chamber, wherein the overbalance payload chamber contains propellant and can be activated to create a transient overbalance condition. 
     
     
         7 . A method for performing a perforating operation in a subterranean formation, comprising:
 using a perforation gun assembly having an acid payload chamber and a perforating gun payload chamber, or a chamber containing both an acid payload and a perforating gun payload; and   releasing acid from the acid payload chamber while simultaneously creating a perforation in the subterranean formation.   
     
     
         8 . The method of  claim 7 , further comprising releasing an acid precursor by perforating microencapsulated acid particulates and simultaneously creating a perforation in the subterranean formation. 
     
     
         9 . The method of  claim 7 , wherein the acid payload comprises microencapsulated acid particulates with a polymeric shell and an acid or acid precursor core. 
     
     
         10 . The method of  claim 9 , further comprising:
 releasing the microencapsulated acid payload from the acid payload chamber, and   activating the perforating gun payload chamber while simultaneously releasing acid or acid precursor by perforating microencapsulated acid particulates and creating a perforation in the subterranean formation.   
     
     
         11 . The method of  claim 10 , wherein the acid payload chamber and the perforation gun chamber can be released/activated sequentially and substantially in the same location, and the acid and/or acids precursor can be target-released into the perforation. 
     
     
         12 . A method for performing a perforating operation in a subterranean formation, comprising:
 using a perforation gun assembly having an acid payload chamber and a perforating gun payload chamber, or a chamber containing both an acid payload and a perforating gun payload, and an overbalance payload chamber, wherein the overbalance payload chamber contains propellant and can be activated to create a transient overbalance condition; and   releasing an acid payload from the acid payload chamber while simultaneously creating a perforation in the subterranean formation.   
     
     
         13 . The method of  claim 12 , further comprising:
 activating the perforating gun payload chamber, and simultaneously, releasing acid or acid precursor by creating a perforation; and   activating the overbalance payload chamber and pushing the released acid or acid precursor into the perforation.   
     
     
         14 . The method of  claim 13 , further comprising releasing a microencapsulated acid payload from the acid payload chamber;
 activating the perforating gun payload chamber, and simultaneously, releasing acid or acid precursor by perforating microencapsulated acid particulates and creating a perforation; and   activating the overbalance payload chamber, pushing the released acid or acid precursor into the perforation.   
     
     
         15 . The method of  claim 14 , wherein the acid payload chamber, the perforation gun chamber, and the overbalance chamber can be released/activated sequentially and substantially in the same location, and the acid and/or acid precursor can be target-released into the perforation. 
     
     
         16 . The method of  claim 15 , wherein the microencapsulated acid particles range from 0.001 micrometers to 5000 micrometers. 
     
     
         17 . The method of  claim 15 , wherein the microencapsulated acid particles comprise one of HCl, H 2 S0 4 , HF, H 3 P0 4 , or HNO 3 . 
     
     
         18 . The method of  claim 15 , wherein the microencapsulated acid particles comprise an organic acid. 
     
     
         19 . The method of  claim 18 , wherein the organic acid comprises one of acetic acid, tartaric acid, formic acid or lactic acid. 
     
     
         20 . The method of  claim 15 , wherein the microencapsulated acid particles are encapsulated in an inert polymer material.