Abstract: Wayne Field: A Horizontal Drilling Case Study

Jeffrey B. Jennings, Robert Post Johnson

Beginning in the spring of 1994, studies of Wayne field located on the northeastern flank of the Williston Basin were initiated to determine the feasibility of using horizontal drilling to increase recoverable reserves in the field.

The Wayne subinterval is one of several shoaling-upwards cycles within the Mission Canyon Formation of the Mississippian Madison Group. The reservoir pay averages 24% porosity, 100 millidarcys permeability, and 50% water saturation. Vertical wells, since field discovery in 1957, typically IP for 70 bopd and 20% water with a rapid decline within a few months to 10 bopd and 90% water. This type of well performance is characteristic of severe water coning for which horizontal development can help to minimize.

In late 1994 and early 1995 the Ballantyne Hedges #7H and GeoResources O. Fossum #H1 were drilled. The wells recorded IPs of 280 bopd/5 bwpd and 390 bopd/80 bwpd respectively. After six months of production both wells stabilized at approximately 110 bopd with a 35% water cut. Projections indicate that each horizontal well will recover 250,000 bbls of oil as compared to 115,000 bbls for an average vertical well and will do so in half the time. These early results provide a significant improvement over the vertical production and would seem to be reducing water coning. Three more horizontal wells are planned for the fourth quarter of 1995.

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