Recent Woodford Oil Completions in Central Oklahoma
Paul W. Smith
West Star Operating
The Woodford Shale is the primary objective of an OIL play being developed by West Star Operating Company in central Oklahoma. To date, West Star has drilled and completed several oil productive verti-cal wells and two horizontal wells in the Woodford Shale. A third hori-zontal well has been drilled and cased, but waiting stimulation. The highest peak oil production from a vertical well is 392 BOPD. The horizontal wells have observed daily oil production rates of up to 215 BOPD. West Star has produced more than 60,000 barrels of OIL from the Woodford Shale in this play since 2010. The oil varies from 29 to 39 API-gravity and the associated gas is rich in liquids, ranging up to 1440 BTU. The treatment method appears to have more influ-ence on recovery than does the gravity of the oil – as the well that has produced the most oil to date also has the lowest API gravity oil. West Star has continually experimented, developed, and improved its fracture stimulation techniques with every completion. The Woodford Shale is up to 300 feet thick and found at depths from 4500 – 7000 feet in the study area.
Experimentation of completion techniques is easier to monitor and cheaper to conduct in vertical wells than in horizontal wells. During an effort to progressively evolve the completion techniques to identify the ―best practice method‖ prior to utilization in horizontal wells, it was demonstrated that the Woodford Shale can be economically produced from vertical wells. The changes in completion method resulted in increasing productivity from 4362 BO in the first 365 days of production (average 12 BOPD) to 3763 BO in the first 31 days of production (average 103 BOPD). There is not enough oil production history in this area, as of yet, to fully predict the best cycle (zone) for stimulation within the Woodford Shale.
This presentation will briefly address the Woodford Shale in terms of geological setting, deposition, and maturation to put these factors into context. Extractions from 3-D seismic will be shown. West Star has also observed long distance fracture influence. In one vertical well, the effect of the stimulation could be observed in a different vertical well more than one-half mile away. West Star has examined fracture orientation in the vertical and horizontal wells using borehole imaging. Many fractures are contained within 1-2 inch bedding planes with adjacent beds above and below showing no fractures at all. Results from the image logs will be presented. A comparison of the locations, completion methods, and results of six of the wells drilled and producing from the Woodford Shale will be the primary focus of the presentation with an emphasis on what we have observed and what we think we have learned so far.
AAPG Search and Discovery Article #90184 © AAPG Woodford Shale Forum, Oklahoma City, Oklahoma, April 11, 2013