Named after the city of Three Forks, Montana, the Three Forks Group is a stratigraphic unit in the Williston Basin. Below the surface the Three Forks is referred to as the Three Forks Formation, and lies below the Bakken Formation and above the Birdbear Formation. Straddling 5 states/provinces, The Three Forks Group covers parts of Montana, North/South Dakota, Saskatchewan and Manitoba.
What is the Three Forks?
The Three Forks Formation dates back to the Devonian Era (419-358 million years ago), and is composed of dolomite, mudstone and bituminous shale. Ranging in thickness from 35m-80m (110ft-260ft), the Three Forks Formation has 4 different layers. Below is a cross-section illustrating the deposition and structure of the Bakken and Three Forks groups.
The uppermost Three Forks layer (Three Forks 1) is producing, while Three Forks 2, 3, and 4 are still largely exploratory. Average log porosity for Three Forks 1 has been calculated at 7.9% and shows low permeability.
Bakken and Three Forks well spuds hit a new high last year, with 747 well starts in the Williston Basin in the 3rd quarter of 2013. This accounted for more than 8% of the 9,175 wells that were spud in the U.S. The number of wells started per quarter was up nearly 50% over the previous 18 months, while the rig count had fallen by just over 10%. How can this be? Experience and pad drilling continue to drive development times down. By utilizing multi-well pad drilling, more wells are drilling using the same number of rigs. While at the same time, as more wells are drilled, engineers get more and more efficient with their drilling practices.
Not every well in the Williston Basin targets the Bakken and Three Forks, but estimates suggest that the plays account for more than 95% of the activity in the Williston Basin.
Oil & Gas Production
Oil production for the Three Forks is often included in production statistics with the overlying Bakken Formation. While masking the actual productivity of the Three Forks itself, the two formations together show massive recovery potential. On April 30, 2013 the United States Geological Survey (USGS) combined potential production estimates of The Three Forks and Bakken. The USGS estimates that using current technology, 7.4 billion barrels of oil, 6.7 trillion cubic feet of natural gas and 530 million barrels of natural gas liquids can be recovered from the Bakken and Three Forks formations!!
Companies have been combining horizontal drilling with multi-stage fracture stimulation and longer laterals to yield better productivity from each well. Over the past few years the number of frac stages has dramatically increased. Only a few years ago the number of frac stages were much lower (single digits), but now they are commonly above thirty, and many above forty. This increases initial production rates but also increases the cost of drilling. If frac stages could be strategically positioned to target the absolute finest points within the lateral section, this could yield the best well performance. Configuring frac stages in a way that 1 or more could be eliminated would substantially drive completion costs down. The retrieval of formation evaluation data provides Completions Engineers with the information required to customize their completion program. With Cordax's Logging While Tripping (LWT) system, open hole logs can be obtained safely and more cost effectively in any horizontal well.