Open-hole intelligent well deployed within deep-water, pre-salt carbonate reservoir
- Cost reduction appr. 30%
- Intelligent completion
- Reliable zonal isolation
A client offshore Brazil needed a slim-well design for an open-hole, cementless, multi-zone completion for a deep, pre-salt reservoir. Welltec’s Advanced Well Architecture (AWA) system had previously been used to enable efficient deployment of two-zone, intelligent well systems. Additionally, Welltec® also has a well known track record with deploying a metal expandable Welltec Annular Barrier (WAB®) to achieve a cementless, open-hole seal.
In these deep well environments, cement seal integrity is challenging to achieve due to a multitude of reasons, including losses and equivalent circulating densities. For this intelligent well deployment, Welltec proposed using metal expandable WABs to enable a slim-well, three-zone, open-hole completion.
As part of the intelligent completion, Welltec installed two triple 812WABs with control line feed-through mounted on 5-1/2” fiber. The intelligent completion was run in hole in a single trip with the interval control valves opened.
Circulation, including a formation pre-wash, was performed to break down the mud cake. The internal control valves were then closed. The tubing was pressurized, achieving a fast, surface-controlled setting of the WABs during the production packer and tubing pressure test. Injectivity tests and a zonal acid stimulation were successfully performed.
The WABs enabled an open-hole, intelligent well deployment. This completion system resulted in a substantial reduction in cost and risk because of the slim well design and the removal of the liner, cementing, and perforating operations. The estimated cost reduction is in the range of 30% of the total well construction cost.
Zonal bore pressures are available to the client in real time, confirming full sealing achieved by the WABs during the stimulation, and the three-zone internal control valve system is fully compatible. The client is now realizing increased net present value owing to the accelerated oil production and reliable life-of-well zonal isolation.