ABSTRACT
The recent global expansion in the development of unconventional oil and gas assets has also resulted in a tremendous increase in the number of extended horizontal drilling and hydraulic fracturing projects in the Bakken. The United States is presently the largest global crude oil producer, and the Bakken Formation in North Dakota is one of the major contributors to this achievement. However, the wastewater produced from these increased oilfield activities are highly saline (∼170,000 to 350,000 ppm TDS) and no technology currently available can satisfactorily treat it. As a result, more than 90% of wastewater in the Bakken is disposed of by deep injection into disposal wells. However, there are growing environmental and operational concerns about the sustainability and impacts of this approach. Research has shown that cumulative wastewater injection in some areas could increase the chances of earthquakes in those areas. However, if this produced water is efficiently treated, it could be reused in hydraulic fracturing operations or to support coal mining and irrigation activities. All these applications would reduce the need for wastewater injection and reduce the demand for fresh water used in hydraulic fracturing operations across North Dakota. For this purpose, we propose an enhanced supercritical technology we call Supercritical Water Extraction – Enhance Targeted Recovery to handle the issue of high TDS of flowback and produced water in the Bakken.
Oil production from unconventional reservoirs, such as the Bakken, has become very important and their optimal development has been studied in detail worldwide, especially in North America. This is because, over the past few years, unconventional reservoirs have substantially added to the national reserves of the US hydrocarbon resources. Recently the United States has become self-sufficient in hydrocarbon needs, a feat it has been trying to achieve for many decades. The United States did not only stop the importation of crude oil but was also willing to export and add crude oil export as part of the source of revenue generating streams. The Bakken Formation is contributing immensely to this feat. In 2019, oil production from the top 10 Bakken producers rose to 176,603,000bbl from 13,500 producing wells at an average of 3142bbl/month from each well (North American Shale Magazine, 2020). For maximum primary oil recovery, between 60,000 to 80,000 wells must be drilled in all the oil producing counties in the Bakken; it is projected that this cannot be achieved until 2025 (North American Shale Magazine, 2020). However, with the current trend in drilling and completions technologies, the projected time may be shortened because the advancement in both the horizontal drilling and hydraulic fracturing technologies (Kolawole et. al., 2019a; Wigwe et. al., 2019a) in recent years has made it easy and has also reduced the time it usually takes to drill wells in the Bakken. The good thing is that there is a great reduction in both the drilling and completions cost (Wigwe et al., 2019b). However, as with every technological advancement, there are some problems.
