Lundin Energy Norway is one of the leading oil companies on the Norwegian Shelf when it comes to conducting formation and long-term reservoir tests in the wells we drill. This dedication to collecting data has proven to yield significant results over time. The Norwegian Petroleum Directorate recognises this effort as important for the wider industry.
Formation testing, or ‘drill stem tests’ (DSTs), is the only method for direct evaluation of reservoir connectivity over greater distances, and provides a lot of information about how oil and gas flow in the reservoir and into wells. The alternative is to run model calculations using static data such as fluid samples, logs and core samples.
In simple terms, a core sample or a well log can supply information from the exact spot where drilling is taking place. Based on that information, model calculations can be made for a larger area, but they cannot confirm whether a well is in contact with a sufficiently large reservoir volume. With a formation test, we collect real flow information, allowing us to “see” up to 3-4 kilometres out from the well.
Dynamic data from formation tests provide a far better basis for making decisions, both as to whether or not a field will be developed, or for drainage strategy and well placement for producing fields. However, data collection does represent a significant cost.
“Keeping a drilling rig in operation to collect data is costly, but in many cases we’ve seen that it would have been far more expensive not to do this,” says Exploration and Reservoir Development Director Per Øyvind Seljebotn. “One example is Edvard Grieg, the field would likely not have been developed, if our assessment was based solely on static data,” he says.
One of the first appraisal wells on Edvard Grieg, (16/1-10), is a good example. The model based on well logs indicated that that the discovery probably would not be commercially interesting with a relatively poor reservoir in conglomerate rocks. However, the formation test revealed a continuous, very good reservoir in sandstone, 1500 metres out from the well.
“The information from this particular well led to two extremely important decisions,” Per Øyvind Seljebotn explains. “We forged ahead with development plans for Edvard Grieg, and we made the decision to drill an exploration well in licence PL501, which turned out to be the Johan Sverdrup field, a very significant field indeed!.”
IOR from Day One!
Information obtained from formation testing in the exploration phase makes a valuable contribution by ensuring optimal placement of production wells. But it is also true that collecting data throughout a field’s lifetime is of great significance, and contributes to increased recovery, IOR (Increased Oil Recovery).
“Our motto for the Edvard Grieg field has been “IOR from Day One”. We could have carried out the well program and drainage strategy according to the original idea, but we opted to continue our comprehensive data collection to ensure maximum utilisation of the resources in the field,” says Harald Selseng, Subsurface Lead at Lundin Energy Norway. “We’ve drilled 2 pilot wells and 3 appraisal wells on the Edvard Grieg field after we submitted the development plan (PDO),” says Selseng.
Recognition from the NPD
Lundin Energy Norway was recently nominated for the IOR award by the Norwegian Petroleum Directorate (NPD), in part for its work on the Edvard Grieg field. In its nomination announcement, the NPD points out the long-standing fact that formation testing has not been prioritised on the Norwegian Shelf, but that Lundin distinguishes itself in a positive manner in this area, and can point to extremely good results on discoveries and fields both in the North Sea and the Barents Sea.
The jury also emphasised Lundin’s willingness to test complex reservoirs types that are new on the Norwegian Shelf.
Lundin’s work on data collection/DST will be presented at an event sponsored by the Norwegian Petroleum Directorate. See the broadcast here.
Broadcast starts Tuesday 29 September at 9.00 am.