Steam-Drive Project in the Schoonebeek Field, The Netherlands

Abstract

In Sept., 1960, a steam-drive project was started in the solution-gas drive area of the Schoonebeek field. A pattern of three five-spots and one four-spot was selected covering an area of 65 acres. The pay in the project urea has good lateral continuity and dips slightly to the northeast ; it is about 80 ft thick and permeability increases from 1,000 md at the bottom to approximately 10,000 md at the top. Ths oil originally in place was 12.6 X 10" bbl. The oil has an in situ viscosity oj about 180 cp. At the start of the steam drive the cumulative primary production due to solution-gas drive amounted to 4 per-;~~~the oil originally in place. Reservoir pressure had dropped to about 120 psi artd no significant primary reserves remained. Some 11.3 million bbl of steam (ai ' steam quantities are expressed in barrels of water vaporized) have been injected, resulting in production of an additional 4.1 X I(Y bb[ of oil, or 33 vercent of the oil originally in place. This corresponds to a cumulative oil-steam ratio oj 0.37 bbll b bl. It appears that the steam pref eren-tially moves updip while liquids are produced mainly from downdip wells. Observations indicate that the steam flows through only the upper part of the formation. The lateral steam distribution in the pattern is unsatisfactory since several production wells hardly reacted and, hence, contributed Iitt!e to the oii production. Production performance and results Jrom material bal-' ante calculations agree sa?isjactorily with the results of large-scale laboratory experiments. On the basis of these experimental reslilts the steam drive, together with a cold water follow-up, is expected to bring ultimate recovery to a value of at least 50 percent of the oil originally in place. No serious production problems have been encountered. However, due to mechanical failure, two old production wel[s and one injection weli had to be replaced. An extension of the steam drive in this area i.r under cmrstrt4ctirrn.