Heavy oil developments are not straightforward. “This also applies to the Kraken development in Quad 9 of the UK Northern North Sea,” as reservoir engineer Jan Manoharan from Enquest says. However, given an anticipated recovery factor of over 25% over the longer term, the development is certainly moving in the right direction for Enquest (70.5%) and partner Waldorf (29.5%).
The Kraken development is one of the biggest heavy oil fields across the UK Continental Shelf. Oil is stratigraphically trapped in Paleocene Heimdal Formation sandstones at a depth of around 1,200 m on the East Shetland Platform.
“With a significant step up in oil viscosity, Kraken presented challenges for reservoir development, artificial lift and topside design. In addition, we needed to come up with a development concept that limited up front capital spend,” Jan explains.
In order to make the development a success, the integration of reservoir data, wells and topsides were key. “The wells were drilled in 1,200 m horizontal sections with relatively straightforward design, which combined with in-house drilling capabilities and class-leading rig performance, resulted in all wells drilled significantly ahead of schedule and under budget,” Jan adds.
The use of an already existing and custom-built FPSO limited capital expenditure ahead of production. On the flipside, this came with significant operational challenges which were overcome to achieve in excess of 90% production efficiency.
“Defining targets based on seismic data has proven to be accurate and all wells were delivered on prognosis. In addition, a line drive pattern with shallow injectors has been an efficient way to provide pressure support and sweep,” Jan says.
Attend the DEVEX 2022 conference next week (10-11 May) and listen to Jan’s talk on Day 1 to find out more about how Enquest managed to successfully develop Kraken.
Near-field opportunities
Enquest is also looking beyond the current field outlines. “There are multiple near field opportunities in the largely undeveloped western flank of the field. The delivery of wells into this part of the field is underpinned by the broadband, multi-azimuthal seismic survey that was acquired in 2021.”
“We are investigating side-track opportunities for by-passed pay and to improve sweep efficiency within the field itself. There is also agreement with the joint venture partner to look at topsides de-bottle necking,” adds Jan.
“Given the buoyant oil price,” Jan concludes, “we are looking at accelerating opportunities where it’s prudent to do so but will remain disciplined in our investment decisions regardless of the oil price.”
HENK KOMBRINK
