Method for fracturing activity and intensity monitoring and pressure wave resonance analysis

Abstract

A method for characterizing a hydraulic fracture treatment both operationally and in a subsurface formation includes inducing a pressure change in a well drilled through the subsurface formation. At least one of pressure and a time derivative of pressure is measured in the well for a selected length of time. At least one physical parameter of at least one fracture is determined using the measured pressure and/or the time derivative of pressure. A method of evaluating hydraulic fracturing treatment and operations by monitoring resonant structures present while fracturing.

1 . A method for characterizing a hydraulic fracturing operation in a subsurface formation, comprising:
 inducing a pressure change in a well drilled through the subsurface formation, the pressure change inducing Stoneley waves in the well;   measuring at least one of pressure or a time derivative of pressure in the well for a selected length of time; and   in a computer, determining at least one or more of (i) a physical parameter, (ii) a change in the at least one physical parameter with respect to time, of the subsurface formation, or (iii) a wellbore condition parameter, determined using the measured at least one of pressure or the time derivative of pressure wherein the at least one physical parameter, the change with respect to time and the wellbore condition parameter is determined from frequency shifts in the measured pressure or time derivative.   
     
     
         2 . The method of  claim 1  wherein the inducing a pressure change comprises pumping a hydraulic fracture treatment or operating an acoustic source which propagates a pressure pulse into fluid in the well. 
     
     
         3 . The method of  claim 1  wherein the at least one wellbore condition parameter comprises at least one of fracturing fluid pumping rate, fracturing fluid density, fracturing fluid pressure, fracturing fluid pressure change, fracture proppant concentration, fracturing fluid viscosity, or fracturing fluid chemical composition, wherein the at least one wellbore condition parameter is repeatedly determined during a pumping of a fracture treatment stage. 
     
     
         4 . The method of  claim 1  further comprising measuring noise using a plurality of sensors comprising at least one of pressure transducers, hydrophones, accelerometers, microphones, or geophones to reduce surface-based noise and/or to eliminate certain frequencies in the measured at least one of pressure or time derivative of pressure. 
     
     
         5 . The method of  claim 1  wherein the at least one physical parameter or change in the physical parameter with respect to time is determined in the computer from at least one of frequency, quality factor and amplitude of a resonance in the measured pressure or time derivative. 
     
     
         6 . The method of  claim 1  wherein the inducing a pressure change in the wellbore is caused by a resonance inside a wellbore-fracture system, or inside the wellbore. 
     
     
         7 . The method of  claim 1  wherein the inducing pressure change comprises inducing microseismic activity in the formation. 
     
     
         8 . The method of  claim 1  further comprising, in the computer, determining a position in the well of at least one of a diameter change in the well, a material property of the well, a fluid property of the wellbore contents, a viscosity of the fluid, a flow blockage in the well, a screenout in the well or a surface imperfection in the well using measurements of reflections of the induced pressure change. 
     
     
         9 . The method of  claim 1  wherein a relationship between fracture treatment pumping parameters and resonances is established, monitored, and optimized in the computer. 
     
     
         10 . The method of  claim 1  wherein the at least one physical parameter is determined after completing pumping the hydraulic fracture treatment. 
     
     
         11 . The method of  claim 1  further comprising determining the at least one physical parameter is determined prior to pumping the hydraulic fracture treatment. 
     
     
         12 . The method of  claim 1  wherein the inducing a pressure change comprises water hammer generated by changing a flow rate of fluid into or out of the well or into or out of a section of the well. 
     
     
         13 . The method of  claim 1  further comprising in the computer determining fluid connectivity between the well and a second well by measuring at least one of pressure and time derivative of pressure in the second well. 
     
     
         14 . The method of  claim 1  wherein the at least one physical parameter comprises stimulated connected volume. 
     
     
         15 . The method of  claim 1  wherein the stimulated connected volume is estimated in the computer using at least one of frequency, quality factor, and amplitude of at least one resonance in the measured at least one of pressure or the time derivative of pressure. 
     
     
         16 . The method of  claim 1  wherein the at least one physical parameter comprises near wellbore connectivity estimated from dispersion and attenuation of resonances in the measured pressure or pressure time derivative. 
     
     
         17 . The method of  claim 1  wherein selected parameters are measured and selected characteristics are determined in the computer by comparing the determined at least one physical parameter for each of a plurality of different fracture treatment stages with respect to a normalized value of the at least one physical parameter. 
     
     
         18 . A method for characterizing a hydraulic fracturing of a sub surface formation, comprising:
 inducing a pressure change in a well drilled through the subsurface formation, the pressure change inducing Stoneley waves in the well;   measuring at least one of pressure and a time derivative of pressure in the well for a selected length of time; and   in a computer, determining one or more of, (i) at least one physical parameter and (ii) a change in the at least one physical parameter with respect to time, of at least one fracture using the measured at least one of pressure or the time derivative of pressure from properties of Stoneley wave resonances in the measured pressure or pressure time derivative.   
     
     
         19 . The method of  claim 18  wherein the inducing a pressure change comprises pumping a hydraulic fracture treatment. 
     
     
         20 . The method of  claim 18  wherein the inducing a pressure change comprises operating an acoustic source which propagates a pressure pulse into fluid within the well. 
     
     
         21 . The method of  claim 18  wherein the at least one physical parameter and changes in the at least one physical parameter are determined in the computer, and parameters comprising fracture fluid pumping rate, fracture fluid density, fracture fluid pressure, fracture fluid pressure change, fracture fluid proppant content, fracture fluid viscosity, and fracture fluid chemical concentration are continuously measured during pumping of at least one fracture stage. 
     
     
         22 . The method of  claim 18  wherein the at least one physical parameter fracture comprises fluid connectivity. 
     
     
         23 . The method of  claim 18  wherein permeability is determined from dispersion and attenuation of a resonance caused by the induced pressure change. 
     
     
         24 . The method of  claim 18  wherein the at least one physical parameter comprises fracture proppant distribution. 
     
     
         25 . The method of  claim 18  wherein a fracture geometry is estimated using quality factor of at least one resonance in the measured pressure or the time derivative. 
     
     
         26 . The method of  claim 18  wherein the at least one physical parameter comprises fracture length. 
     
     
         27 . The method of  claim 26  wherein the fracture length is determined from a reflection resonance time or frequency in the measured pressure or time derivative. 
     
     
         28 . The method of  claim 18  wherein the at least one physical parameter comprises fracture extent or fracture thickness determined while pumping fracturing fluid into the well or after pumping fracturing fluid into the well. 
     
     
         29 . The method of  claim 18  wherein the at least one physical parameter comprises one or more of fracture length growth rate, fracture width growth rate, fracture thickness growth rate, fracture tip growth rate, fracture tip proppant concentration, fracture tip distance from the well or estimated fracture closure time. 
     
     
         30 . The method of  claim 18  further comprising, in the computer, converting the measured at least one of pressure and pressure time gradient to the frequency domain and determining at least one physical parameter of the fracture by spectral analysis of the pressure change or reflections thereof in the well. 
     
     
         31 . The method of  claim 18  wherein the at least one physical parameter comprises an estimated total number of fractures having a same resonance using a determined amplitude of at least one resonance at a particular frequency. 
     
     
         32 . The method of  claim 18  further comprising analyzing a quality factor of resonances to estimate fracture geometry or fracture network complexity. 
     
     
         33 . The method of  claim 18  wherein a peak central frequency of a pressure wave resonance is used to determine length and width dimensions of the at least one fracture. 
     
     
         34 . The method of  claim 18  wherein an amplitude of a peak amplitude frequency of a pressure wave resonance is used to determine a number of fractures having a same length or width dimension. 
     
     
         35 . The method of  claim 18  wherein a spectral width of at least one resonance in the pressure or pressure time derivative measurements is used in the computer to estimate at least one of a viscosity of fluid in the at least one fracture, a formation fracture permeability, and a product of viscosity and permeability in the at least one fracture. 
     
     
         36 . The method of  claim 18  further comprising in the computer repeating the determining the at least one physical parameter for a plurality of fractures and comparing the at least one physical parameter for a plurality of different fracture stages in the well, for a plurality of wells, or for a plurality of multiple well surface pads to optimize hydraulic fracturing design. 
     
     
         37 . The method of  claim 18  further comprising measuring noise using a plurality of sensors comprising at least one of pressure transducers, accelerometers, microphones, and geophones to reduce surface-based noise and/or to attenuate certain frequencies in the measured at least one of pressure and time derivative of pressure. 
     
     
         38 . The method of  claim 18  wherein a fracture proppant distribution is determined in the computer from at least one of a fracture mouth reflection coefficient and a resonance frequency of the pressure change.