Aker BP first ever to use new well stimulation method offshore
The first successful “Single-Trip Multi-Frac” campaign has been executed on the Valhall field. This specific method of well stimulation has never been done offshore before, the company said in its release.
With a sleeve installed in the completion that can be opened and closed down in the well, it is now possible to fracture several zones with only on trip into the well.
The method significantly reduces the cost of the well because less time is needed for use of vessels and equipment.
“The traditional method takes two-three days to fracture a single zone of the reservoir. With ‘Single-Trip Multi-Frac’, we can now do two zones in a day. We also see a potential for doing this more efficiently,” says Stian Ø. Jørgensen, head of the the Well Intervention and Stimulation Alliance in Aker BP.
The Valhall field has always needed stimulation to maximise production from the wells. This is because the field consists of chalk formations with low flow rates. A stimulation vessel and coiled tubing are needed for this operation.
The actual stimulation takes place by creating fractures in the reservoir, by high pressure pumping in sand mixed with a fluid system into the reservoir. The process is called fracturing and contributes to improve flow. Several zones in the reservoir must be fractured, and with the normal method, the coiled tubing is pulled out completely for each zone – an extensive and time-consuming process.
“What’s new about ‘Single-Trip Multi-Frac’ is that several zones can be fractured with just one trip down into the well. This is done with the aid of a sleeve installed in the completion that can be opened and closed down in the well,” explains Jørgensen.
This allows us to pump sand mixed with a fluid system into the well, while the coiled tubing remains in the hole the entire time. When one zone has been fractured, you close and move on to the next zone.
A total of four zones were stimulated using the new method during the ‘Single-Trip Multi-Frac’ campaign on the G10 well at the Valhall field centre in November. Three of the zones were stimulated on just one trip down in the well. The same method was also successfully applied on the first well on Valhall Flank West.
Valhall has produced one billion barrels since the field opened in 1982. The ambition is to produce another billion barrels.
In November, Aker BP entered into an alliance for well intervention and stimulation with Stimwell Services and Schlumberger, two of the partners in the “Single-Trip Multi-Frac” project.