Characteristics of discrete and basin-centered parts of the Lower Silurian regional oil and gas accumulation, Appalachian basin: Preliminary results from a data set of 25 oil and gas fields
U.S. Geological Survey Open-File Report 98-216
Appendix P
Lenox gas field (Ln)
Location: | Ashtabula County, Ohio (Lenox and Morgan Twps.) |
Discovery date: | 1960 |
Depth (ft): | ~3,200 |
Hydrocarbon type and GOR: | Gas and major associated oil |
Structural setting: | Structural terrace and southeast-plunging structural noses superimposed on a regional southeast-dipping homocline |
Stratigraphic name of reservoir: | "Clinton" sands; lower part of the red Clinton; best reservoirs consist of braided stream deposits confined to east-west trending channels; reservoirs also described as sand tongues and associated channels |
Trap: | Stratigraphic; locally influenced by southeast-plunging anticlinal noses; no recognizable updip pinchout of sandstone reservoirs; an ~5 mi-wide zone of little to no gas production adjoins the updip part of the field (water block?) |
Porosity: | F ave = 7.5%, range 5.9 to 9.6%, 10.1 to 14.6% in one well; rarely exceeds 15 to 18% also reported |
Permeability: | Kave = 4 mD, as high as 10 mD; K = 0.048 mD also reported |
Natural fractures: | Indirect evidence from decline-curve analysis |
Diagenetic features: | Secondary quartz is the dominant cement |
Water saturation and volume/salinity of produced water: | Sw (ave) = 45%; all wells produce some fluids oil and (or) water; salinityave = 220,014 ppm, range 174,095 to 253,218 ppm, sample number=3, salinity = 112,000 to 155,000 ppm also reported |
Gas/water and oil/water contacts: | None reported; oil occupies the structurally highest parts of the field, water has been a problem in several of the structurally lowest wells in the southwestern part of the field |
Reservoir pressure: | 1,200 to 1,250 psi (0.38 to 0.39 psi/ft); 1409 psi (0.42 psi/ft) also reported |
Bottom-hole temperature: | 95° F |
Well spacing: | 80 acres; 40 acres may be necessary for the most effective drainage |
Ultimate production (EUR per well): | Three groups of decline curves are recognized: a well drilled early in the history of the field has an EUR = 170 MMCF of gas |
References: | Kell (1980); McCormac and others (1996); McMullin (1976); Munsart (1975); Oil and Gas Journal (1969); Sanders (1991) |
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