Abstract
Injecting seawater into producing formations with barium-rich formation water has been avoided for decades due to concerns of barium sulfate scale formation impairing production. The local barium-rich formations unfortunately bring immediate scaling risk due to severe tendencies to form barite when the seawater sulfate contacts barium-rich formation waters. This scaling challenge has driven the industry to utilize freshwater-based fluids for most completions operations which include fracturing and other sand control methods. As multizone completions have increased in frequency over the past decade, the logistical challenges of providing freshwater-based systems have grown greater. To overcome these challenges, a newly developed seawater-based fracturing fluid system has provided benefits over the traditional freshwater-based system.
In this paper, we present case studies of four multizone completions in deepwater Gulf of Mexico which utilized a newly developed seawater-based fracturing fluid integrated with a polymeric scale inhibitor package. All four wells have barium-rich formation waters present and range in temperatures from 194 to 260°F (90 to 127°C). We share the challenges overcome in the designs and operation, field overview data, lab testing results, field deployment results, and initial production results. We also discuss the benefits seen by using seawater-based fracturing fluids for deepwater FracPac jobs to streamline logistics by eliminating the need for supply vessels and reducing cleaning wastes, CO2 emissions and freshwater use.
Unlike proposals in other publications which was characterized by Hou et al. (2023), the seawater based fracturing fluid used on these treatments did not remove the seawater's sulfates by nano-filtration, forced precipitation of sulfates, electrodialysis, or any other means. Sulfate removal techniques were investigated, but currently they are not deemed practical for stimulation vessel use due to the extra equipment requirements and associated processing times.
