Stout shoes, a hammer and a magnifying glass: what have they got in common? They equip you to take part in a geological field trip for DEA – and set off with specialists on a journey back through time. At a specially selected site our specialists study rock formations that are millions of years old. They can read the outcrops towering above their heads like book, and use this information to draw their conclusions about analogue formations underground – where large quantities of oil and gas may well have been formed.
Fossils provide important information about the rock strata
Of course you need specialist skills to understand the significance of such outcrops and examine in detail the samples taken from them. Particular attention is paid to the grain, structure and texture of the rock, with the lithology of a rock describing its physical characteristics visible at an outcrop or in a core sample. Our specialists have to be experts in palaeontology as well, since fossils in the sediment rocks and general traces of primeval life can deliver crucial information. The shells of prehistoric microorganisms are used to determine the age of the rock strata and any connections between different boreholes.
Specialists examine rock samples under the microscope
Our geologists map outcrop and quarry walls and other planar areas for subsequent interpretations of the structure and facies of the rock. They take samples of rocks from which our lab experts in Wietze make wafer-thin sections for investigation under light and scanning electron microscopes. Here, they are particularly interested in the composition of the rock, its grain size and the types of pores. These lab experts have to find the answer to one particular question: how porous and permeable is the rock?
Satellite images and research round off the picture
But DEA´s geologists don't just carry out their research at outdoor sites or in a lab. They also study the relevant literature in libraries, databases and the internet to collect all the information they can on a specific region. Any information that is not freely available will be purchased from sources all over the world – specialist studies, seismic data on the upper part of the Earth's crust or exploration findings. Satellite pictures and aerial photographs are also of particular interest because specialists can use them to identify where faults, lines or folds have formed in the Earth's crust.
Reservoir rock is the key source of information
A whole series of geological investigations are only carried out once the first wells have been drilled into the reservoir body. Since such bodies are characterised by a higher degree of porosity and permeability than the surrounding sediment rocks, they are highly interesting as potential reservoir rocks for oil and gas. Our geological investigations are focused on the internal structure, size and geometry of the reservoir body so that we can put together a detailed picture of the reservoir.
And at the end of all this research work comes the real defining moment for the geologists: they are required to come up with the most accurate forecast possible of the probable volume of oil or gas in the area under investigation. Because only then can DEA decide on future development or exploration activities.