Flooding of Gas Cap in Norfolk Garr Sand Unit
- H.A. Nelson (The Blackwell Oil & Gas Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- October 1958
- Document Type
- Journal Paper
- 14 - 17
- 1958. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 5.8.5 Oil Sand, Oil Shale, Bitumen, 4.1.2 Separation and Treating, 2 Well Completion, 4.3.4 Scale, 5.1.1 Exploration, Development, Structural Geology, 1.6 Drilling Operations, 6.5.2 Water use, produced water discharge and disposal, 5.4.1 Waterflooding, 4.6 Natural Gas, 2.4.3 Sand/Solids Control
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The West Norfolk Garr Sand Unit, which contains a large gas cap, is being successfully flooded using a conventional five-spot pattern and filling the gas cap with water to prevent loss of oil by migration into the gas cap.
Pilot water injection was commenced in July, 1953, utilizing two 10-acre, five-spot patterns. Increased oil production was first obtained in Oct., 1954, and gas-cap injection began in Feb., 1955. Over 4.5 million bbl of water have been injected into the gas cap to achieve fill-up. It is concluded that the gas cap of reservoirs with shallow dips may be filled with water to prevent loss of oil into the cap by migration with no adverse effects on the oil-bearing portion of the reservoir.
Water flooding the Pennsylvanian sands in Oklahoma is becoming increasingly important. Numerous fields drilled during the late 1940's and early 1950's are now reaching their economic limit, and the successful water flooding of some of these fields is stimulating considerable interest. Gas caps have created difficult problems in many of these fields. The successful flood of the West Norfolk field has led to the development of additional similar projects.
Ten years ago water flooding of the shaly sands, such as the Peru, was believed to be impracticable. However, more accurate engineering and geological techniques, combined with improved operating techniques, have led to the successful flooding of fields similar to the West Norfolk field.
Primary Development and Production History
Primary reserves in the West Norfolk field have been developed during two periods: (1) from 1927 to 1930 and (2) from mid-1949 to 1952. In Oct., 1927, gas was discovered in the Peru sand (now known as the Garr sand) on the east side of the field and 10 gas wells were soon drilled along this eastern edge. Continued production from these wells resulted in some going to oil, and after turning to oil the wells produced from 5 to 10 BOPD. In mid-1949 the discovery well was completed in the oil sand. This well, now Unit Well 16, produced 60 BOPD after a 60-qt shot. Further development resulted in the drilling of 60 oil wells.
Primary production from 870 acres totaled 870,000 bbl from mid-1949 to July 1, 1953, when the field was unitized for water flooding. It is estimated that of this 870 acres the oil column encompassed 645 acres, while the gas cap encompassed 225 acres. Total primary recovery was estimated at 1,097,000 bbl.
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