One-hundred and fifty years ago, in the year 1856, a farmer called Peter Reimers was digging a well in a field when he struck layers of oil-bearing sand. This find near the town of Heide/Hemmingstedt marked the dawn of the petroleum age, which soon came into full swing as automobiles became more widespread and gained in importance. While the oil strike by Edwin Laurentine Drake in Titusville in the U.S.-state of Pennsylvania in 1859 may have attracted more publicity at the time, in Germany is was Schleswig-Holstein where the running was made in the early stages.
During this trailblazing phase, the resourceful chemist Ludwig Meyn started working with the smelly, viscous oily substance and soon managed to distil a number of useful products from it. By the year 1860, the growing range of these products included items such 'asphalt solar oil' for burning in petroleum lamps, and 'asphalt benzine, used in the preparation of a quick-drying coffin varnish'. Increasing industrialization led to a steadily growing demand for cart and engine grease, bitumen, diesel oil, gasoline and other mineral oil products.
The so-called 'Heider Ölkreide' (oil chalk) was discovered in the year 1870. This substance is a highly viscous oil contained in chalk, and early attempts to extract the oil were unsuccessful. Starting in 1920, the company Deutsche Erdöl AG (DEA) started to mine the oil chalk reservoir near Hemmingstedt. Since the oil chalk deposit was too deep below the surface for an open-cut mining operation, and as the oil was too viscous to be extracted using production wells, workers drove shafts and tunnels below ground in order to mine the oil-soaked chalky rocks. Mining in Dithmarschen: an extremely tough job, but also well-paid in its time.
Even so, the oil extracted in this operation could not stand up to the competition from the U.S., and production ceased after only a few years. In was only in the 1930s that mining of the deposit resumed once more. During the war years, domestic sources of oil were considered indispensable. A 13-kilometer system of underground shafts and tunnels was built, and some 160,000 tonnes of oil chalk were produced in this way. When the war ended, the unprofitable oil chalk mine was closed once again.
The real breakthrough in crude oil production in Schleswig-Holstein occurred in 1935, when the Holstein 2 well struck liquid oil at a depth of 400 meters. DEA developed the reservoir and continued production from the Heide/Barsfleth field over many years until 1992, when the operation proved no longer commercially viable. During this time, no less than 2.44 million tonnes of crude had been produced.
After the Second World War, extensive seismic surveys provided a more detailed picture about what was waiting below the surface. Geologists were particularly interested in the structures found alongside the flanks of the commonly occurring salt diapirs, since these resembled so-called oil traps, deposits that are covered by a layer of impermeable rock. In 1952, an exploration well in the Boostedt-Plön area confirmed the presence of such a reservoir. This was the first strike in eastern Holstein, and it was to be followed by a number of others over the next few years: six geologically unconnected deposits (Boostedt-Plön, Warnau, Plön-Ost, Kiel, Schwedeneck) stretching over a distance of 65 kilometers, like pearls on a string. The well-known oil field Schwedeneck-See, with its two offshore production platforms A and B, was the last deposit developed in eastern Holstein, in 1981. The combined total volume of crude produced from these fields in eastern Holstein had reached more than 17 million tonnes by the middle of the year 2000.
After oil production ceased in eastern Schleswig-Holstein, production in the west, off the coast of Dithmarschen, increasingly gained in importance: as long ago as the 1950s and 60s, geologists had considered this region a likely prospect for oil and had conducted seismic surveys. In 1965, the Büsum Dogger 1 well encountered signs of oil, but not in commercial quantities. It was not until the summer of 1980 that oil in commercially viable quantities was struck by the Mittelplate 1 well. Construction of the artificial Mittelplate Island started in June 1985, and oil production began in October 1987. Since then, 21 wells have been sunk from Mittelplate Island, producing about 10 million tonnes of crude to date. Constant upgrades to the island's production facilities and the expansion of transport capacities have made it possible for the initial annual production volumes of around 200,000 to 300,000 tonnes of crude to be increased steadily over the years since.
In conjunction with the pipeline link established in 2005 between the Mittelplate Drilling and Production Island and the treatment plant at the Dieksand Land Station, a new powerful drilling rig will allow production on the island to be boosted from a past level of approx. 850,000 tonnes to a volume ranging from 1.2 to 1.6 million tonnes of crude per annum. Unlike the earlier method of transporting the oil to the mainland on barges, the new stainless-steel pipeline makes oil transportation independent of prevailing weather conditions.
Since the spring of the year 2000, it has also become possible to extract crude from the eastern sector of the Mittelplate reservoir directly from the mainland, thanks to advanced drilling technologies. The extended-reach production wells are among the longest in the world and cut right through the Büsum salt diapir. These wells have already produced more than 6 million tonnes of crude. As the remaining oil deposits in Germany are largely exhausted, the Mittelplate field, which accounts for just under 65 per cent of national crude oil reserves, is the only major German oil field with a viable future.
For this reason, leading-edge technologies will be deployed in the continuing effort to exploit the Mittelplate field in future. These technologies include extreme extended-reach wells that are driven horizontally through oil deposits using the heavy-duty electrically powered T-150 drilling rig, a machine that is capable of sinking wells in a radius of up to six kilometers around Mittelplate Drilling and Production Island. Additional exploration measures will be needed in order to access and develop further resources, and planning for these measures is already under way.
The current high level of oil prices is also making projects commercially viable that were not considered feasible only a few years ago. Accordingly, the focus is now returning to the mature fields of Schleswig-Holstein once again, as state-of-the-art 3-D seismics are used to locate, and perhaps develop, additional oil deposits in areas around the mature fields. In line with this trend, RWE Dea has acquired the exploration rights to the Preetz concession for a period of five years. Planning is under way to re-evaluate the remaining oil potentials of some of the old oil fields, such Plön-Ost, Preetz and Schwedeneck using new methods and concepts, with the aim of extracting the remaining crude.
Even the oil chalk deposits, considered commercially unviable in the past, are now being re-examined: in 2005 RWE Dea started to have a closer look at the Dithmarschen deposits. So far in the course of this exploration program, the two investigation wells Lieth 1001 and Wiemerstedt 1001 have been sunk. The objective here was to obtain oil samples and drill cores which provide information about the reservoirs in the oil-impregnated Upper Cretaceous strata. Only once the data acquired has been evaluated in detail will it be possible to consider the possibility of developing a suitable method for extracting the oil. The data is still being analyzed at this time. One thing is clear already: as these oil chalk deposits are unique in the world, the usual methods used to extract oil cannot be deployed in this case.
The methods needed in the exploration for, and production of petroleum and natural gas are becoming ever more complex, sophisticated and hence more costly. In an effort to expand its knowledge base and acquire the necessary expertise, RWE Dea is investing more in fundamental research. Working closely with scientific institutes based in the state of Schleswig-Holstein, a range of research projects are under way aimed at investigating the possibility of continuing the long tradition of oil production in Germany's northernmost state as well as in other regions.
Most Popular Articles