Abstract
The Bakken boom in North Dakota has been well documented. From a development perspective, the majority of the acreage has been drilled with an initial well to hold the acreage and the emphasis has shifted to infill drilling. As the development progresses, the industry seeks to apply more sustainable practices which includes the recycling of produced water. A number of efforts are underway to consider the use of produced water for well stimulation, and the economics are expected to improve with infrastructure such as central gathering systems. From an economic and environmental point of view, reuse of produced water in the Williston Basin is a sustainable practice to conserve water and save on well completion cost.
A number of technical challenges accompany the application of produced water in well stimulation including stimulation design, execution, and effectiveness. Considerable attention is required regarding fluid chemistry including stimulation additives, guar-based gels, crosslinkers, and friction reducers (FRs) used in slickwater. For example, properties of friction reducers change considerably in the light of the high salinity of Bakken produced water. Effective friction reducers are critical for slickwater jobs that are pumped at high rates of 70 bpm and the early slickwater stages using in hybrid fracs (combination of gel and slickwater). Achieving that high rate is key to effectively divert fluid flow and maintain sufficient rate to transport proppant in a long lateral.
This paper provides insight into the effectiveness of using produced water into slickwater designs in the Bakken petroleum system. The work discusses screening of various experimental and commercial FRs to determine their individual effectiveness with fresh water and produced water. The efficiency of a few tested FRs is then measured in actual field treatments, and we conduct a comparison of the frictions measured in field and lab to provide a methodology for proper comparison of the two, enabling a reasonable forecast of frictions measured in the lab to pipe frictions expected under field conditions.
