Refrac efficiency monitoring

Abstract

A method of treatment of a subterranean formation penetrated by a wellbore, where the well has a plurality of previously stimulated intervals includes: a) pumping a viscous pill into a well with pressure curve registration by a wellhead pressure sensor; b) determining a depth (L) of treatment fluid entry point and depth uncertainties (L); c) generating a water hammer at the wellhead which excites tube waves; d) determining the depth (L) of the treatment fluid entry point and the depth uncertainties (L) by processing a water hammer by high frequency pressure monitoring method; e) determining a tube wave velocity from a combination of data from (b) to (d); f) performing a fracturing treatment; and g) generating a water hammer at the wellhead at the end of the fracturing treatment (f) with refined depth of treatment fluid entry point and with lower uncertainty.

1 . A method of treatment of a subterranean formation penetrated by a wellbore, wherein the well has a plurality of previously stimulated intervals comprising:
 a) pumping a viscous pill into a well with pressure curve registration by a wellhead pressure sensor;   b) determining a depth (L) of treatment fluid entry point and depth uncertainties (ΔL);   c) generating a water hammer at the wellhead which excites tube waves;   d) determining the depth (L) of the treatment fluid entry point and the depth uncertainties (ΔL) by processing a water hammer by high frequency pressure monitoring method;   e) determining a tube wave velocity from a combination of data from (b) to (d);   f) performing a fracturing treatment; and   g) generating a water hammer at the wellhead at the end of the fracturing treatment (f) with refined depth of treatment fluid entry point and with lower uncertainty.   
     
     
         2 . The method of  claim 1 , wherein multiple stimulation treatments are pumped in the well. 
     
     
         3 . The method of  claim 1 , wherein the data frac treatment is performed before pumping a viscous pill. 
     
     
         4 . The method of  claim 1 , wherein the viscous pill is a portion of fluid with a viscosity of at least 100 times higher than a viscosity of a wellbore fluid. 
     
     
         5 . (canceled) 
     
     
         6 . The method of  claim 1 , wherein the water hammer is generated by shutdown of pumps at the surface. 
     
     
         7 . The method of  claim 1 , wherein the high frequency pressure monitoring method comprises processing of a pressure signal. 
     
     
         8 . The method of  claim 7 , wherein processing of the pressure signal comprises preliminary signal filtering. 
     
     
         9 . The method of  claim 7 , wherein processing of the pressure signal further comprises processing with cepstrum analysis. 
     
     
         10 . The method of  claim 1 , wherein a diverter is additionally pumped into the wellbore after (g). 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . The method of  claim 1 , wherein the depth determination (L) has a resolution of at least 100 ft (30.48 m). 
     
     
         14 . (canceled) 
     
     
         15 . The method of  claim 1 , further comprising performing a completion operation, wherein the completion operation is selected from the group of plug-and-perf completions or slide and sleeve completions.