Method and apparatus for improving wellbore productivity with piezoelectric crystals

Abstract

A system and method of enhancing production of oil and gas from a reservoir is provided. More specifically, the present invention relates to systems and methods of positioning piezoelectric crystals in a production interval of a well. When activated, the piezoelectric crystals produce displacement (elongation and compaction) and cavitation within the wellbore to move particles within the well and fractures in the reservoir. In one embodiment, a fluid which includes a proppant material and a plurality of piezoelectric crystals is pumped into the well. The fluid may be a hydraulic fracturing fluid. In another embodiment, a plurality of piezoelectric crystals are interconnected to a body of a downhole assembly. The downhole assembly is configured to be positioned within a production interval of a wellbore. In one embodiment, the body includes a hollow bore. In one embodiment, the piezoelectric crystals are interconnected to at least one of an exterior surface of the body and an interior surface of the body within the hollow bore.

What is claimed is: 
     
         1 . A downhole assembly for enhancing flow rates from a wellbore, comprising:
 a body for positioning within a production interval of the wellbore; and   a plurality of piezoelectric crystals interconnected to the body, the piezoelectric crystals having predetermined sizes and being interconnected to an exterior surface of the body, wherein, when the downhole assembly is positioned within the wellbore, at least one of the plurality of piezoelectric crystals expands or contracts in response to at least one of a change in temperature, a change in pressure, and a change in fluid flow rate in the wellbore.   
     
     
         2 . The downhole assembly of  claim 1 , wherein the body includes a bore defining an interior surface. 
     
     
         3 . The downhole assembly of  claim 2 , wherein at least one piezoelectric crystal is interconnected to the interior surface of the body. 
     
     
         4 . The downhole assembly of  claim 1 , wherein a first subset of the plurality of piezoelectric crystals generate low frequencies of between approximately 0.1 kHz to approximately 100 kHz when activated. 
     
     
         5 . The downhole assembly of  claim 4 , wherein a second subset of the plurality of piezoelectric crystals generate high frequencies of between approximately 10 kHz and approximately 100 MHz when activated. 
     
     
         6 . The downhole assembly of  claim 5 , wherein the first subset of the plurality of piezoelectric crystals are positioned on the exterior surface of the body and the second subset of the plurality of piezoelectric crystals are positioned on an interior surface of the body. 
     
     
         7 . The downhole assembly of  claim 1 , wherein the body comprises at least one of a solid bar and a mesh material. 
     
     
         8 . The downhole assembly of  claim 1 , further comprising a power source to provide electricity to the plurality of piezoelectric crystals. 
     
     
         9 . The downhole assembly of  claim 1 , further comprising a controller operable to send a signal to activate and deactivate the plurality of piezoelectric crystals. 
     
     
         10 . The downhole assembly of  claim 1 , wherein the plurality of piezoelectric crystals have sizes and frequencies selected based on characteristics of the wellbore including at least one of the depth, length, temperature, flow rate, hydraulic fracturing interval, reservoir permeability, formation type, and reservoir porosity. 
     
     
         11 . A method of enhancing a flow rate from a wellbore in a reservoir, comprising:
 positioning a downhole assembly in a production interval of the wellbore, the downhole assembly including:
 a body; and 
 piezoelectric crystals interconnected to the body, a first subset of the piezoelectric crystals operable to generate low frequencies and a second subset of the piezoelectric crystals operable to generate high frequencies; and 
   triggering at least one of the plurality of piezoelectric crystals, wherein the at least one piezoelectric crystal expands and/or contracts which causes fines in fractures of the reservoir to repair and improve the permeability of a hydraulic reservoir proximate to the wellbore.   
     
     
         12 . The method of  claim 11 , further comprising flowing fluid from the wellbore to flush the fines out of the fractures. 
     
     
         13 . The method of  claim 11 , wherein the at least one piezoelectric crystal is triggered by a change in one or more of a temperature, a pressure, and a rate of fluid flow in the wellbore. 
     
     
         14 . The method of  claim 11 , further comprising selecting at least one of a pattern, a size, and a frequency of the plurality of piezoelectric crystals based on a characteristic of the wellbore and the reservoir. 
     
     
         15 . The method of  claim 11 , wherein the body comprises a screen or a solid bar for placement in the wellbore. 
     
     
         16 . A method of enhancing the production of a hydrocarbon reservoir, comprising:
 providing a wellbore extending a predetermined length and depth in the hydrocarbon reservoir;   providing a fluid which includes a proppant material and a plurality of piezoelectric crystals; and   pumping the fluid into the wellbore, wherein at least one of the plurality of piezoelectric crystals contracts in response to conditions within the wellbore.   
     
     
         17 . The method of  claim 16 , wherein at least one of the plurality of piezoelectric crystals is transported into a fracture in the hydrocarbon reservoir. 
     
     
         18 . The method of  claim 16 , wherein the plurality of piezoelectric crystals generate frequencies of between approximately 0.1 kHz and approximately 1 GHz when activated. 
     
     
         19 . The method of  claim 16 , wherein the piezoelectric crystals comprise up to approximately 80% by volume of the fluid. 
     
     
         20 . The method of  claim 16 , wherein the at least one of the plurality of piezoelectric crystals contracts in response to a reduction of at least one of a fluid temperature, a fluid pressure, and a rate of fluid flow.