Systems and methods for increasing fracture complexity using acoustic energy

Abstract

A system is configured to fracture a formation surrounding a subterranean wellbore. In one example, the system includes a tool string configured to be deployed in the wellbore, and an acoustic pulse generator connected to the tool string and configured to transmit acoustic pressure pulses into the formation. The acoustic pulse generator is configured to generate acoustic pressure pulses with a magnitude of at least 1000 pounds per square inch.

I claim: 
     
         1 . An system for fracturing a formation surrounding a subterranean wellbore, the system comprising:
 a tool string configured to be deployed in the wellbore;   an acoustic pulse generator connected to the tool string and configured to transmit a plurality of acoustic pressure pulses into the formation, wherein the acoustic pulse generator is configured to generate acoustic pressure pulses comprising a magnitude that is at least approximately 1000 pounds per square inch (psi).   
     
     
         2 . The system of  claim 1 , wherein the acoustic pulse generator is configured to generate acoustic pressure pulses comprising a magnitude that is at least approximately 6000 psi. 
     
     
         3 . The system of  claim 1 , wherein the acoustic pulse generator is configured to generate acoustic pressure pulses comprising a magnitude that is at least approximately 12000 psi. 
     
     
         4 . The system of  claim 1 , wherein the acoustic pulse generator is configured to generate acoustic pressure pulses comprising a magnitude in a range from approximately 1000 to approximately 16,000 psi. 
     
     
         5 . The system of  claim 1 , wherein the acoustic pulse generator comprises a high-pressure, moving-piston, pulse engine comprising:
 a combustion chamber;   a pipe comprising a first end connected to the combustion chamber; and   a disperser connected to a second end of the pipe.   
     
     
         6 . The system of  claim 5 , wherein the combustion chamber is configured to combust an oxidized fuel and transmit combustion gases through the pipe and around the disperser to generate an acoustic pressure pulse. 
     
     
         7 . The system of  claim 1 , further comprising a plurality of acoustic sensors arranged adjacent the wellbore and configured to detect the acoustic pressure pulses transmitted by the acoustic pulse generator. 
     
     
         8 . The system of  claim 7 , wherein the acoustic sensors comprise at least one of a piezoresistive strain gauge, or a capacitive, electromagnetic, piezoelectric, or optical pressure sensor. 
     
     
         9 . The system of  claim 7 , further comprising a computing device communicatively coupled to the acoustic sensors, wherein the computing device is configured to:
 receive information from the acoustic sensors related to the acoustic pressure pulses; and   determine at least one property of the formation based on the received information.   
     
     
         10 . The system of  claim 1 , further comprising an acoustic isolator connected to the tool string above the acoustic pulse generator, wherein the acoustic isolator is configured to dampen the acoustic pressure pulses. 
     
     
         11 . The system of  claim 1 , wherein the acoustic pulse generator is configured to be connected to the tool string. 
     
     
         12 . The system of  claim 1 , further comprising a wire line configured to be deployed into the wellbore, wherein the acoustic pulse generator is configured to be suspended in the wellbore by the wire line. 
     
     
         13 . The system of  claim 1 , wherein the acoustic pulse generator comprises at least one tank configured to house at least one of an oxidizer, a fuel, or a pressurant. 
     
     
         14 . The system of  claim 13 , wherein the at least one tank is configured to house sufficient fuel and oxidizer to allow the acoustic pulse generator to generate at least 20 acoustic pressure pulses. 
     
     
         15 . The system of  claim 1 , further comprising a supply line connected to and configured to supply at least one of an oxidizer, a fuel, or a pressurant to the pulse generator. 
     
     
         16 . The system of  claim 1 , wherein the acoustic pressure pulses are configured to increase the pressure within at least a portion of the formation by approximately 8-10 times. 
     
     
         17 . A method comprising:
 pumping a pressurized fluid down a wellbore;   communicating the pressurized fluid to a surrounding formation to fracture the formation; and   transmitting a plurality of acoustic pressure pulses into the fractured formation, wherein an amplitude of at least one of the acoustic pressure pulses is at least approximately 1000 psi.   
     
     
         18 . The method of  claim 17 , wherein the acoustic pressure pulses are transmitted into the fractured formation after the pressurized fluid is communicated to the formation. 
     
     
         19 . The method of  claim 17 , wherein the acoustic pressure pulses are transmitted into the fractured formation while the pressurized fluid is being communicated to the formation. 
     
     
         20 . The method of  claim 17 , wherein the acoustic pressure pulses are transmitted by an acoustic pulse generator arranged adjacent the fractured formation on the tool string. 
     
     
         21 . The method of  claim 20 , wherein the acoustic pulse generator comprises sufficient oxidizer and fuel to generate the plurality of acoustic pressure pulses. 
     
     
         22 . The method of  claim 21 , wherein the acoustic pulse generator comprises sufficient oxidizer and fuel to generate at least 20 acoustic pressure pulses. 
     
     
         23 . The method of  claim 20 , further comprising transmitting an oxidizer and a fuel through at least one supply line connected to the acoustic pulse generator, wherein the acoustic pulse generator is configured to generate the plurality of acoustic pressure pulses using the oxidizer and the fuel transmitted through the at least one supply line. 
     
     
         24 . The method of  claim 20 , further comprising controlling, by the acoustic pulse generator, at least one of an amplitude and a frequency of the plurality of acoustic pressure pulses. 
     
     
         25 . The method of  claim 17 , further comprising:
 sensing the plurality of acoustic pressure pulses transmitted into the fractured formation; and   determining at least one property of the fractured formation based on the sensed acoustic pressure pulses.   
     
     
         26 . The method of  claim 17 , further comprising damping the plurality of acoustic pressure pulses in the wellbore above the fractured formation. 
     
     
         27 . The method of  claim 17 , wherein an amplitude of at least one of the acoustic pressure pulses is at least approximately 6000 psi. 
     
     
         28 . The method of  claim 17 , wherein an amplitude of at least one of the acoustic pressure pulses is at least approximately 12,000 psi. 
     
     
         29 . The method of  claim 16 , wherein an amplitude of at least one of the acoustic pressure pulses is in a range from approximately 1000 to approximately 16,000 psi. 
     
     
         30 . The method of  claim 17 , wherein the acoustic pressure pulses are configured to increase the pressure within at least a portion of the formation by approximately 8-10 times.