Terrestrial Toxicity of Synthetic Gas-to-Liquid versus Crude Oil–Derived Drilling Fluids in Soil

Lisa Arneson Westbrook, Darcy A. Chase, Joseph Mudge, Sarah A. Hughes, Delina Lyon, Meijun Dong, Deborah Carr, Todd A. Anderson

Research output: Contribution to journalArticle

Abstract

Unlike most other conventional petroleum products that are derived from crude oil, gas-to-liquids (GTLs) are petroleum products that are synthesized from natural gas (methane). This process results in GTL products having no sulfur and low aromatic content, so they should have less impact on human health and the environment compared with crude oil–derived products. The GTL have been registered for use as nonaqueous base fluids (NABF) in drilling muds, which help in the process of drilling wells for oil and gas extraction. It is through these uses and others that they enter terrestrial environments. This study aims to determine whether GTL were less toxic to terrestrial soil biota than conventional NABF used for land-based drilling, e.g., as diesel and low-toxicity mineral oil (LTMO). The fate and impact of these fluids under more realistic soil and aging conditions of a common west Texas (USA) oil-producing region (i.e., sandy loam soil with low organic matter and a hot arid climate) were assessed. Acute terrestrial toxicity studies were conducted on the soft-bodied terrestrial invertebrate earthworm (Eisenia fetida) along with three plant species, alfalfa (Medicago stavia), thickspike wheatgrass (Elymus lanceolatus), and fourwing saltbrush (Atriplex canescens). Changes in microbial community structure of the soils following additions of NABF were examined. The GTL NABF had lower toxicity compared with conventional NABF like diesel and LTMO, as measured by invertebrate toxicity, plant seed germination, and impact on the microbial community.

Original languageEnglish
Pages (from-to)721-730
Number of pages10
JournalEnvironmental Toxicology and Chemistry
Volume39
Issue number3
DOIs
StatePublished - Mar 1 2020

Keywords

  • Gas-to-liquids
  • Nonaqueous base fluid
  • Sandy loam
  • Terrestrial toxicity

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