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Figure Above: Match of the entire DH4 upper zone data with the alternative model.

Figure Above: Injection rate and volume forecasts from the falloff model with an operating 
pressure of 130 bar.

DH4 Middle zone

The second test run in DH4 in the Adventdalen Well Park was conducted in the middle test zone, also referred to as 
the upper zone (of two) in the full test report. This test, which started September 5 and ended October 15, 2013, was 
conducted in a 26 m open-hole section in the interval 773 – 799 m in the De Geerdalen formation of Late Triassic age. 
The test was run after the lower zone was plugged with cement and the BQ string cut at 795 m, leaving an open-hole 
completion from the bottom of the NQ string at 770 m.

The test sequence in the DH4 upper zone started with roughly 8 minutes injection at around 143 m3/d followed by a 
step-rate test of about 1.5 hours and an injection period of 6.22 hours at a fairly stable rate around 210 m3/d and a 915 
hours falloff.

Even after 915 hours of falloff data there was no direct evidence of radial flow or transition towards radial flow. A 
direct determination of the formation permeability is therefore not possible, but two estimates have been obtained 
from two different analyses. The first assumes that natural fractures are activated near an injection-generated long 
hydraulic fracture with enhanced permeability in an inner zone. The second scenario assumes early data to be domi-
nated by fracture closure, with only late-time data used directly to determine properties.

The following points summarize key observations and results from the DH4 middle zone data:

• Formation is under-pressured by at least 46 bar with the sea level as reference at 28.5 bar at the gauge, but the 

exact formation pressure is difficult to determine

• Well clearly hydraulically fractured from the injection
• Not possible to determine permeability directly due to a lack of radial-flow data
• Not possible to determine fracture dimension directly without known permeability
• Falloff data can be matched with a model with early data dominated by a zone near the injection-generated frac-

ture with enhanced permeability (“stimulated zone”)

• The model above has a fracture half-length of 160 m, is bounded in one direction 12.4 m from the fracture and 

unbounded in the other with a width of 500 m, the permeability of the inner (stimulated) zone is 1 md, the extent 
of this zone is 4.4 m from the fracture in both directions, the permeability of the outer zones is 0.12 md, the radius 
of investigation is 135 m in the open direction after 915 hours

• Falloff data can also be matched in an approximate way with a model with early data dominated by fracture-clo-

sure effects treated as a changing storage effect

• This last model has a fracture half-length of 143 m and a permeability of 0.1 md (from a lack of uniqueness it is 

possible to use the permeability 0.12 md for the scenario)

• The main results from the two analyses scenarios are qualitative with the suggested formation scenarios uncer-

tain, especially about factors controlling early data

Injection forecasts covering 1E5 hours (11.4 years) give the same results for the two model scenarios, with rates drop-
ping below 5 m3/d after 8 months and total volumes 10600 m3 after 11.4 years with low initial pressure 25 bar and 
bottom-hole flowing pressure 130 bar.