Determination of Recovery Factor in the Bakken Formation, Mountrail County, ND

Abstract

This paper was prepared for presentation at the 2009 SPE International Student Paper Contest at the SPE Annual Technical Conference and Exhibition. Abstract An accurate value for recovery factor in the Bakken shale is needed for estimation of ultimate recovery. Published estimates of recovery factor in the North Dakota region of the Bakken vary greatly and examination of historical production from this region reveals that very few published recovery factor estimates are accurate. In this paper, recovery factor for the Bakken shale in Mountrail County, ND, was determined using three different methods. The first method involved review of the literature and an examination of recovery factors historically used by companies operating in the area. The second method was based on material balance, while the third method was based on decline curve analysis. Results from all three methods were integrated and indicate that the most likely value for recovery factor in the Bakken shale is approximately 7%. In the absence of more definitive performance data, these results can be used by companies to estimate ultimate recovery and to help make investment and development decisions in the Bakken shale. Introduction The Bakken shale is not a new discovery, having originally been found to contain oil in the 1970s. Recently, thanks to a higher oil price and the introduction of new and effective well completion technologies, production in this area has increased dramatically. Fig. 1 shows the tremendous increase in production, which began in 2006 in Mountrail County, ND. Wells drilled in the Bakken shale come with a high price tag. The target formation is at a depth of approximately 10,000 ft and requires laterals of anywhere from 5000 - 10,000 ft in length. The formation is extremely tight and has a low matrix permeability of approximately 0.05 mD, with limited evidence of natural fractures. Fracture treatments are quite large, having anywhere from 6 to 18 stages and requiring several million pounds of sand. Only with high oil prices, lengthy laterals and huge fracture treatments can the Bakken formation produce oil economically.

Has the Economic Stage Count Been Reached in the Bakken Shale?

“…The average oil gas ratio ranges from 200 to 1,600 SCF/BBL across the play (Pilcher et al, 2012). Oil in place is estimated to be at 5,000 MBBL/mi 2 for the Bakken (McMaster, 2010;Clark, 2009;& Powell et al, 2007).…”

Hydraulic Fracture Orientation for Miscible Gas Injection EOR in Unconventional Oil Reservoirs

“…And the reservoir temperature is dependent on the specific depth. The temperature is 220︒F at the depth of 10,500 ft in Mountrail County, ND (Clark, 2009) and the temperature is 240 ︒F at the depth of 10,000 ft in Richland, MT (Wiley, 2004).…”

Numerical simulation study on miscible EOR techniques for improving oil recovery in shale oil reservoirs

“…The available information refers to 100-900 billion barrels in Bakken only. However, the predicted recovery from primary depletion could lead to 7% only of original oil in place (Clark 2009). Furthermore, some investigators argued that the primary recovery factor is still in a range of 1-2% in some of these plays in North America (Wang et al 2016).…”

“…Therefore, oil recovery factor from primary depletion has been predicted typically to be less than 10% (LeFever and Helms 2008;Clark 2009;Alharthy et al 2015;Kathel and Mohanty 2013;Wan and Sheng 2015;Alvarez and Schechter 2016).…”