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A peripheral water injection system was begun in the Abqaiq Field of Saudi Arabia in 1956. The initial system consisted of gravity injection into three nose wells. Following the completion of the flank installations and electrification in 1958, injection rates were increased to the present rate of 30 to 40 MBD per well. The field water injection rate is approximately 300 MBD. The volumetric effectiveness of injected water is 50 per cent and is expected to increase to 70–80 per cent.

The water supply source, the Wasia formation, is a prolific aquifer containing non-potable water of 8,000 ppm total dissolved solids. The water is corrosive, however, corrosion is controlled by inhibitor injection. The Wasia water injection system is a closed pressure system.

A temporary sea water injection system was installed to evaluate the problems of a sea water injection project. The results of this project are presented.


The Abqaiq field was discovered in 1940, but full-scale development did not begin until 1946.

Figure 1 is a structure contour map of the Abqaiq field. For analytical purposes the field has been divided into two areas designated A and B as shown on the map.

At present there are 61 producible wells in the field. They are drilled on a contour pattern and the average spacing is about 5,000 feet.

Initial pressure at -6,500 feet datum was 3,395 psig and the bubble point of the reservoir fluid is 2,545 psig. The reservoir was undersaturated at discovery.

Average solution gas-oil ratio is 850 scf/STB. There has been essentially no change in producing gas-oil ratio. Separation is done at centralized separator plants of which there are three: one, in Area B and two in Area A. The crude goes through separation stages of 500, 250, 50 and 2 psig.

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