Minimizing Environmental and Economic Risks With a Proppant-Sized Solid-Scale-Inhibitor Additive in the Bakken Formation

Abstract

SummaryWithin the past decade, hydraulic fracturing has proved to enhance the efficiency and economics of recovering oil and natural gas from shale formations. In a previous paper (SPE-134414-MS, Gupta et al. 2010), a summary of treatment results from placing a solid scale inhibitor into formations by means of the fracturing process for more than 5 years and in more than 1,500 wells was discussed fully; however, the practice of hydraulic fracturing has come under scrutiny because of concerns about environmental impact, health, and safety. Therefore, a novel, biodegradable scale inhibitor with an outstanding ecotoxicity profile for fresh water incorporated into a solid matrix was recently developed and deployed in North Dakota. For one operator with 150 Bakken producing wells in this area, severe carbonate-mineral scaling in the pump and production tubing has been observed in 22 of these producing wells, which led to well failure (Cenegy et al. 2011), whereas the results from more than 290 Bakken wells now fractured with the new solid-inhibitor additives indicate no reported scale failures to date.This paper provides a detailed description of the first deployment of this environmentally preferred proppant-sized solid-scale-inhibitor additive under severe scaling conditions in the field. In addition, an analytical method developed to track the residual of this additive in the produced fluid containing polysaccharide contaminants is also discussed.