Validation

Paige et al., 1992,1 describe a convincing laboratory, physical model, validation experimental series. In these experiments, prediction of height and length was good. There were indications in the experiments that restricting the wellbore height profile does not prevent HIT from interrogating the full height of the fracture ("the maximum height needs to be close to the fracture mouth relative to the pulse wave length."). "However, the results of other tests show that limiting the area of communication path by making it narrow and tortuous promotes under-estimation of fracture height (although length is unaffected)."

These same authors also described HIT on North Sea injectors with complimentary falloff testing data (refer to Table 1) and a Norwegian sector well that had been in service for five months (Table 2). Finally Table 3, from this same reference is a comparison of various methods.

Table 1.  North Sea Injectors

Item HIT Pressure Falloff
Number of fractures 2 or 3 per well

 
Length (Well 1) 60 m 63 m
Length (Well 2) 38 m 47 m
Length (Well 3) 66 m 45 m


Table 2. North Sea Norwegian Sector Well

Item HIT Pressure Falloff
Fractures Two fractures intersecting the wellbore Complex fracture system
Length Length of top fracture was 29 m >30 m


Table 3. Comparison of HIT-Derived Fracture Dimensions
with Those from Spinners, PFOs and Simulation

Well Location HIT Spinner PFO Simulation

 

 Height (m) Length (m) Height (m) Length (m) Height (m) Length (m)
Canada 1.0

 

 1.3

 

 

 
Canada 1.5

 

 2.0

 

 

 
UK 4.8 60 5.0 63 10 - 15 30 - 75
UK 5.0 38 5.0 47

 

 
UK 3.6 66 50.0 45

 

 
Norway 2.2 22 2.0

 

 

 
Norway 2.0 20 2.0

 

 4 25
Alaska 3.7 38 2.4

 

 

 
Alaska 1.9 18 2.5

 

 

 
Norway 1.7 29 1.5 30 26 46
Norway

 

 29

 

 

 

 46

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