Uncovering hidden potential: Mapping the Rotliegend reservoir

09 November 2017

As a result of the Regional Mapping Project we are assembling a dataset ideal for an initial screening exercise to see where exploration potential still exists.

One of the great benefits of the Regional Mapping project we are currently working on with the Oil and Gas Authority (OGA), is the ability to combine multiple data sources and map types into an interactive Geographic Information System (GIS). Granted there are many high-quality publications available on the geology of the North Sea, however these are often much more static and require georeferencing and digitisation before being utilised in a GIS.

The dataset LR is assembling is ideal for an initial screening exercise to see where exploration potential still exists. Here, we describe an example from the Rotliegend reservoir in the Southern North Sea. It’s only recently that geologists started to realise that the northern margin of the Southern Permian Basin holds economic volumes of gas too. Before that, all the Rotliegend exploration efforts were focused on the Leman sandstone along the southern margin.

The idea that the Rotliegend was unprospective in the north can be reconstructed by looking at the well penetrations in the area. The map on the right shows the Triassic well penetrations in Quadrant 43 (on top of the Rotliegend structural elements map; the lighter the blue the thinner the Rotliegend is). The wells in the northern part of Quadrant 43 either terminate in the Triassic (orange) or just drilled into the Zechstein (green). The Rotliegend was never tested. The map on the left shows the Rotliegend well penetration map, clearly showing the gap in Quad 43 where no wells are drilled into this prospective interval.

Well penetrations Rotliegend - 723x301

By plotting these well penetration maps, an exploration geologist will quickly find out which stratigraphic interval has been tested and which is still waiting for the drill bit to arrive. In addition, the project comes with depositional facies maps, lithostratigraphic well tops, source rocks data and field data, which all help to further inform a new exploration study. Unfortunately, we would need too many figures to show all these different data sources, so you can discover the Southern North Sea maps and databases.

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Project overview:

Lloyd's Register secured two major UKCS projects with the Oil and Gas Authority (OGA) for the UK Continental Shelf (UKCS), for the provision of Regional Exploration Maps and Regional and Field Support Engineering Services to help the OGA independently assess remaining undiscovered resources and improve geotechnical understanding. Read the full detail of the project win.

This is article seven in a series of posts dedicated to our project for the OGA. Read the previous blog post.

Henk Kombrink
Senior Geologist, LR