Method of conducting diagnostics on a subterranean formation

Abstract

A method including providing sensors in injection and observation wells; increasing pressure within the injection well until a fracture extends from an initiation location through a portion of a subterranean formation to an intersection location in the observation well, wherein increasing pressure within the injection well comprises introducing fluid into the injection well; obtaining a measurement indicative of fracture initiation from the first sensor; determining a height of the fracture at the injection well; obtaining a measurement indicative of fracture intersection from the second sensor; determining a volume of fluid introduced between the fracture initiation and the fracture intersection; determining a distance between the initiation location and the intersection location; determining a time lapse between the fracture initiation and the fracture intersection; and using the determined values, calculating a hydraulic fracturing characteristic.

What is claimed is: 
     
         1 . A method comprising:
 a. providing a first sensor in an injection well penetrating a subterranean formation;   b. providing a second sensor in an observation well penetrating the subterranean formation;   c. increasing pressure within the injection well until a fracture extends from an initiation location in the injection well through a portion of the subterranean formation to an intersection location in the observation well, wherein increasing pressure within the injection well comprises introducing fluid into the injection well;   d. obtaining a measurement indicative of fracture initiation from the first sensor;   e. determining a height of the fracture at the injection well;   f. obtaining a measurement indicative of fracture intersection from the second sensor;   g. determining a volume of fluid introduced between the fracture initiation and the fracture intersection;   h. determining a distance between the initiation location and the intersection location;   i. determining a time lapse between the fracture initiation and the fracture intersection; and   j. using the determined values, calculating a hydraulic fracturing characteristic.   
     
     
         2 . The method of  claim 1 , wherein the first sensor comprises a distributed temperature sensor. 
     
     
         3 . The method of  claim 1 , wherein the second sensor comprises a distributed acoustic sensor. 
     
     
         4 . The method of  claim 1 , wherein step (a) comprises placing the first sensor in a substantially vertical portion of the injection well; wherein initiation location is in the substantially vertical portion of the injection well. 
     
     
         5 . The method of  claim 1 , wherein step (b) comprises placing the second sensor in a deviated portion of the observation well; wherein the intersection location is in the deviated portion of the observation well. 
     
     
         6 . The method of  claim 1 , wherein the measurement of step (d) comprises a temperature measurement, the method further comprising:
 obtaining at least one baseline temperature measurement from the first sensor prior to obtaining the temperature measurement of step (d); and   comparing the baseline temperature measurement with the temperature measurement of step (d) to determine a time of initiation.   
     
     
         7 . The method of  claim 1 , wherein the measurement of step (d) comprises a pressure measurement, the method further comprising:
 obtaining at least one baseline pressure measurement from the first sensor prior to obtaining the pressure measurement of step (d); and   comparing the baseline pressure measurement with the pressure measurement of step (d) to determine a time of initiation.   
     
     
         8 . The method of  claim 1 , wherein the measurement of step (f) comprises an acoustic measurement, the method further comprising:
 obtaining at least one baseline acoustic measurement from the second sensor prior to obtaining the acoustic measurement of step (f); and   comparing the baseline acoustic measurement with the acoustic measurement of step (f) to determine a time of intersection.   
     
     
         9 . The method of  claim 1 , further comprising, obtaining a location measurement from the first sensor and obtaining a location measurement from the second sensor, wherein determining the distance of step (h) comprises comparing the location measurements. 
     
     
         10 . The method of  claim 1 , wherein determining the height of the fracture comprises obtaining at least one additional measurement from the first sensor. 
     
     
         11 . The method of  claim 10 , wherein the measurement of step (d) comprises a temperature measurement, wherein the additional measurement from the first sensor comprises a temperature measurement, and wherein determining the height of the fracture comprises comparing the temperature measurements. 
     
     
         12 . The method of  claim 1 , further comprising determining a Young's modulus and Poisson ratio of the portion of the subterranean formation through which the fracture extends, complete elliptical integral of the second kind, and fracture net pressure; wherein the calculating of step (i) further comprises using the determined Young's modulus, Poisson ratio, complete elliptical integral of the second kind, and fracture net pressure. 
     
     
         13 . The method of  claim 1 , wherein the hydraulic fracturing characteristic comprises a leak-off volume. 
     
     
         14 . The method of  claim 1 , wherein the hydraulic fracturing characteristic comprises a leak-off coefficient. 
     
     
         15 . The method of  claim 1 , wherein the hydraulic fracturing characteristic comprises permeability, the method further comprising determining fluid pressure in the fracture, reservoir pressure, viscosity of the fluid, and fluid compressibility, wherein the calculating of step (i) further comprises using the determined fluid pressure in the fracture, reservoir pressure, viscosity of the fluid, and fluid compressibility.