Production Characteristics of the Bakken Shale Oil
- Tan Tran (Texas A&M University) | Pahala Dominicus Sinurat (Texas A&M University) | Bob A. Wattenbarger (Texas A&M University)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 30 October-2 November, Denver, Colorado, USA
- Publication Date
- Document Type
- Conference Paper
- 2011. Society of Petroleum Engineers
- 1.6.6 Directional Drilling, 5.1.5 Geologic Modeling, 5.8.4 Shale Oil, 1.6 Drilling Operations, 5.5.8 History Matching, 1.2.3 Rock properties, 5.2.1 Phase Behavior and PVT Measurements, 2.2.2 Perforating, 4.6 Natural Gas, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 5.8.2 Shale Gas, 5.1 Reservoir Characterisation, 5.7.1 Estimates of resource in place
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There are three main types of well production trends in the Bakken formation. Each decline curve characteristic of these production trends has an important meaning to the production trends of the Bakken Shale play especially type I and type II production trends. In the total of 146 well histories, there are 51 % of wells in Type I production trend. This high percentage of Type I production trend is showing the true characteristic of the Bakken Shale reservoir, which will be discussed later in this paper. Type I production trend has the reservoir pressure drops below bubble point pressure and gas releasing out of the solution. This can be seen on the GOR curve vs. time plot. The cause of reservoir drop below bubble point has been analyzed, and the production of oil in this behavior has driving force from the solution gas. In additional, two linear flow regimes have been observed by looking at the log-log plot of rate against time plot of type I well.
In a type II production trend, production is primary from the matrix. Reservoir pressure is higher than the bubble point pressure during the producing time and oil flows as a single phase throughout the production period of the well. GOR curve is almost constant during the production period. A single linear flow behavior is observed in Bakken Shale play of type II wells. This behavior is characterized by a half-slope on the log-log plot of the oil rate versus time plot.
A type III production trend typically has scattering production data from wells with a different type of trends. It is difficult to study this type of behavior because of scattering data and it will lead to uncorrected interpretation for the analysis.
Calculation procedures are given for OIIP estimation, and the area of matrix drainage between fractures, Acm.
Area of interest covers nine different counties from the Bakken Shale formation. Most counties are from North Dakota state with twenty years of the production histories. These well histories are producing from upper and middle member of the Bakken formation. The production trends from these production histories are inconsistent. Some production trends seem to have better cumulative oil than others. So understanding the production characteristics of the Bakken Shale play is key to success for the operation companies in the area.
This paper describes the production characteristics over the Bakken Shale Oil play, one of the largest shale plays in the United State. OOIP and the area of matrix drainage between the fractures estimations are also given.
Bakken Shale Geology
The Bakken formation is located in the Williston Basin. It was first discovered in 1953 (Breit et al. 1992) when the Antelope Field was discovered. The Bakken Shale play is a shale oil play and has an area of 225,000 squares miles (Price 1986). It is shared by Canada and the United States and is located in North Dakota, South Dakota, Montana, and Saskatchewan.
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