Abstract: Porosity Interconnection Related to Reservoir Homogeneity, Wabek Field, Mountrail County, North Dakota

Michael L. Hendricks

Wabek Field (5 MMBO) was discovered in 1988. There are 31 conventional wells and 2 horizontal wells drilled along a paleo-shoreline trend in the Sherwood interval of the Mission Canyon Formation (Mississippian). As with other Mission Canyon shoreline fields, the reservoir trapping mechanism is an up-dip facies change from permeable lime packstone and grainstone to impermeable dolomite and anhydrite.

An evaluation of porosity trends within the field was conducted to detail the degree of reservoir heterogeneity. This analysis showed that most individual porosity intervals are homogeneous. Cross sections, porosity maps, and water saturation maps all show fair to good interconnection of producing intervals. Because of high production rates in the up-dip portion of the field, a horizontal well was drilled, but it encountered low reservoir pressures and poor production.

Mission Canyon shoreline reservoirs differ in stacking geometries and lithofacies. Based on degree of heterogeneity, some fields will be better candidates for horizontal drilling than others.

Mission Canyon shoreline fields that have dolomite interbeds and multiple reservoir compartments, like Haas, Mohall, and Lucky Mound fields may be ideal candidates for horizontal drilling. Fields with reservoirs and compartments that are dominantly limestone, such as Wabek, Rival, and Lake Darling fields, may have less heterogeneity, and therefore, be less attractive horizontal candidates.

AAPG Search and Discovery Article #90952©1996 AAPG Rocky Mountain Section Meeting, Billings, Montana