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Figure by: Geir Ove Titlestad

Above is a simple drawing of the bleed-off/flare system.

Photo by: Geir Ove Titlestad

Venting and burning Gas - within a controlled operation

This bleed off system was made locally according to drawing and instructions. 

Chemicals and materials

For all well activities there has been; injected total +/-5500 m3 of water into the different formations. The IFE WT 1-3 tracer 
was added to the water injected for the 3 first years (total about 4500 m3). The tracer is liquid and was easy to mix into the 
water. The tracer is also environment friendly - green category. Total estimated consumption of the tracer is +/- 450 liters.

Drilling the wells thorough a fault zone at 400 – 450 m has caused severe problems. By adding KCl salt to the drill water 
the clays of the fault dried out and thereby stabilized the shale formation. Rough estimate of used KCl salt is in the range 
of 10 – 15 tons. 

In addition some sea-salt – about 30 ton. This was used to mix saltwater pills that are placed across the permafrost zone 
in the wells to avoid ice plugs. 

At surface diesel was used to run the pump and air compressor. The total amount of diesel that was used is not available 
for this report. 

Several tons (15-20 t (?)) of cement have been used to secure and isolate the strings in the well and to plug off the old test 
wells. Both industry cement and class G cement. In each cement mix a small amount of harder was added. Total amount of 
harder is estimated to be about 50 - 60 liters. Both the cement and the harder have been supplied by Baker Hughes. 

During well activities the following chemicals and material have been used:
 

diesel,  IFE WT 1-3 trace (1l per 10 000l of water),  sea salt,  KCl salt,  industry cement,  Class G cement,  antifreeze  

 

(avoid freezing of the equipment),  oils (engine oils, hydraulic oil, gear oil etc.)

Gas in wells and related HSE

In 2010 some gas in well DH4 was experienced. When that well was closed in the pressure reached a maximum of 4-5 bars 
and the gas was bled-off within a few minutes when the well was opened for venting. In subsequent operations with Dh5R 
and Dh7a, gas in wells was encountered. Countermeasures have been immediately implemented, as outline in reports of 
Titlestad (2012-2014).

When well DH7a was finalized July 30th, 2012 and the drill rig was moved over to well DH5R, the first incident of major gas 
in wells were encountered. When the rig left well DH7a the well was filled with water. It was decided to install a down-hole 
sensor at 650 m. During the installation of the sensor August 5th it was recognized a smell that is similar to crude oil or 
lighter gas.  When putting an ear close to the opening of the well one could hear a weak sound of gas/air that was blowing. 
At the same time it was observed that the well was no longer filled with water to surface. All these observations indicated 
that there was some gas in the well.  Precaution was immediately taken, and signs forbidding smoking were placed around 
the well. 

During the following days the “gas-flow” from the well Dh7a increased and it was decided to install a blind cap with a pres-
sure gauge. The pressure increased with about 3 bars daily to begin with. When the pressure passed 10 bar it started to be-
come a major concern. Due to the smell of the gas it was expected the gas was flammable and that it therefore represented 
a risk for the planned activities. The pressure did not become stable at the surface before it reached 24-25 bars. The same 
pressure on the well head was later reached for Dh5R.

A bleed-off line with a flare was made. The main objectives of the bleed-off line and the flare were:
 

- Bleed-off the gas and route it away from the well and personnel,

 

- Offered the possibility to burn the gas so it did not represent a risk at the surface.