Asphaltite Uintaite: Approved for Sensitive Marine Environments for Drilling Operations
Authors: Aguilar Katiuska , Montes Ernesto Dario , Sotomayor Ghery , Reimann Ashley 
Published: October 2022

Over the last thirty years the oil and gas industry has implemented high environmental standards to reduce its impact on the environment. Notably, the North Sea and Gulf of Mexico areas have put more stringent regulations in place to protect marine environments.

Drilling and completion fluids services are one of the main components in drilling operations. Since the 1990's environmental performance has become a key aspect in the drilling fluids design. Specific to North Sea environmental regulations, every chemical compound in the drilling fluid formulation must be evaluated before approval for use. One of these additives is uintaite, a naturally occurring asphaltite found exclusively in the Uinta Basin, Utah, USA; recognized globally under the trademark brand name, Gilsonite®.

The benefits of using uintaite in drilling fluids benefits include fluid loss and shale swelling control, lost circulation prevention, and minimizing formation damage. However, uintaite use is limited in deep-water projects due to the misconception that it is the same as other asphaltic additives – referred to as "black powders" – and is harmful if discharged into marine environments. Not only is uintaite not a "black powder", it has also been proven in previous and current studies that uintaite passes all US EPA (Environmental Protection Act) environmental tests for deep-water discharge. Most recently, uintaite has been evaluated as per Convention for the Protection of the Marine Environment of the North-East Atlantic, (OSPAR) to determine its eligibility for unrestricted use in the Norwegian section of the North Sea.

While uintaite falls under the exempt category of Europe's REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals) as a naturally occurring product, OSPAR has further requirements to prove a product is environmentally safe. A comprehensive set of tests dictated by OSPAR guidelines was carried out in specialized and certified laboratories to determine uintaite's ecotoxicological performance in marine environments. The test results from these requirements are detailed in this paper and demonstrate that uintaite is not toxic to marine species, is environmentally inert, and does not bioaccumulate. The findings allowed uintaite to be classified as a Green Product per the OSPAR requirements in 2021.

Once the environmental performance of uintaite was clearly understood – and given its well-known use in the most challenging drilling conditions – a series of formation damage tests were carried out to have a comprehensive set of tests on all performance aspects of this unique material. The rationale behind the specific formation damage tests is to provide data points to discuss the paradigm in the industry that uintaite will create formation damage, the same as other asphaltic additives. The rock-fluid interactions results indicate that uintaite is a safe additive for sensitive ecosystems with an innocuous effect on reservoirs. The study that led to these findings includes the use of Berea sandstone with a standard synthetic base fluid to replicate downhole drilling fluids behavior.