Changes

To determine the trap type of Weyburn field, we have to know what forms the lateral closure. It is not structural because [[dip]] is homoclinal to the southwest. The field lies southeast of the truncation edge of the Midale Member, where it wedges out beneath Triassic rocks and above older Mississippian rocks. Early workers understood this truncation to be the cause of the trap. Yet there is an area lying downdip from the truncation edge of the Midale and updip from the oil pool in which porous Midale vuggy rocks were present but tested wet with shows of oil.

To determine the trap type of Weyburn field, we have to know what forms the lateral closure. It is not structural because [[dip]] is homoclinal to the southwest. The field lies southeast of the truncation edge of the Midale Member, where it wedges out beneath Triassic rocks and above older Mississippian rocks. Early workers understood this truncation to be the cause of the trap. Yet there is an area lying downdip from the truncation edge of the Midale and updip from the oil pool in which porous Midale vuggy rocks were present but tested wet with shows of oil.

This raises the possibility that either a stratigraphic change;<ref name=ch09r70>Winland, H. D., 1972, Oil accumulation in response to pore size changes, Weyburn field, Saskatchewan: Amoco Production Company Report F72-G-25, 20 p. (unpublished).</ref><ref name=ch09r71>Winland, H. D., 1976, Evaluation of gas slippage and pore aperture size in carbonate and sandstone reservoirs: Amoco Production Company Report F76-G-5, 25 p. (unpublished).</ref> Wegelin, 1986; <ref name=ch09r33>Kent, D. M., Haidl, F. M., MacEachern, J. A., 1988, Mississippian oil fields in the northern Williston Basin, in Goolsby, S., M., Longman, M., W., eds., Occurrence and Petrophysical Properties of Carbonate Reservoirs in the Rocky Mountain Region: RMAG Symposium, p. 193–210.</ref> or [[hydrodynamics]]<ref name=ch09r43>Petroleum Research Corporation, 1961, Hydrodynamic exploration for unconformity traps: Research Report A-11, 47 p. (unpublished report, available at Colorado School of Mines Library, Golden, CO).</ref><ref name=ch09r13>Dahlberg, E., C., 1982, Applied [[Hydrodynamics]] in Petroleum Exploration: New York, Springer Verlag, 161 p.</ref><ref name=ch09r24>Hannon, N., 1987, Subsurface water flow patterns in the Canadian sector of the Williston Basin: RMAG 1987 Symposium Guidebook, p. 313–321.</ref> or perhaps both provide the updip, transverse (lateral) seal. From producing wells at Weyburn and nearby Steelman, the oil column height appears to be [[length::600 ft]] [[depth::(183 m]]). This raises the next question: Could the Midale marly beds provide a seal for a 600-ft oil column, or must hydrodynamics be present to augment the seal quality of the Midale marly beds?

This raises the possibility that either a stratigraphic change;<ref name=ch09r70>Winland, H. D., 1972, Oil accumulation in response to pore size changes, Weyburn field, Saskatchewan: Amoco Production Company Report F72-G-25, 20 p. (unpublished).</ref><ref name=ch09r71>Winland, H. D., 1976, Evaluation of gas slippage and pore aperture size in carbonate and sandstone reservoirs: Amoco Production Company Report F76-G-5, 25 p. (unpublished).</ref> Wegelin, 1986; <ref name=ch09r33>Kent, D. M., Haidl, F. M., MacEachern, J. A., 1988, Mississippian oil fields in the northern Williston Basin, in Goolsby, S., M., Longman, M., W., eds., Occurrence and Petrophysical Properties of Carbonate Reservoirs in the Rocky Mountain Region: RMAG Symposium, p. 193–210.</ref> or [[hydrodynamics]]<ref name=ch09r43>Petroleum Research Corporation, 1961, Hydrodynamic exploration for unconformity traps: Research Report A-11, 47 p. (unpublished report, available at Colorado School of Mines Library, Golden, CO).</ref><ref name=ch09r13>Dahlberg, E., C., 1982, Applied [[Hydrodynamics]] in Petroleum Exploration: New York, Springer Verlag, 161 p.</ref><ref name=ch09r24>Hannon, N., 1987, Subsurface water flow patterns in the Canadian sector of the Williston Basin: RMAG 1987 Symposium Guidebook, p. 313–321.</ref> or perhaps both provide the updip, transverse (lateral) seal. From producing wells at Weyburn and nearby Steelman, the oil column height appears to be 600 ft (183 m). This raises the next question: Could the Midale marly beds provide a seal for a 600-ft oil column, or must hydrodynamics be present to augment the seal quality of the Midale marly beds?

==Weyburn structure map==

==Weyburn structure map==