Environmental Performance of Drilling Fluids Selected for Offshore Operations in Venezuela

Venezuelan offshore area in the Caribbean Sea is currently under development. This area contains a diversity of highly sensitive ecosystems which are in some cases associated to important fishery activities. According to Petroleos de Venezuela S.A. (PDVSA) strategies for minimizing impacts in this development, environment friendly drilling fluids were designed, formulated and evaluated. In Venezuela, drilling fluids environment quality is not standardized neither legally regulated. For this reason, in this work, the Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP), Oslo and Paris Commissions (OSPAR) and the Code of Federal Regulations of United States Environmental Protection Agency (CFR- USEPA) general criteria were used in an evaluation of 10 selected drilling fluids. Bioassays for the water soluble and suspended solid fractions were conducted by using four tropical species: Vibrio fischeri (Vibrionaceae), Cyprinodon dearborni (Cyprinodontidae), Skeletonema costatum (Bacillariophyceae) and Litopenaeus vannamei (Penaeidae). Also, anaerobic biodegradation of three synthetic continuous phases and three drilling fluids were performed. Evaluated drilling fluids included Water Based-fluid (WBF), High Performance Water- Based Fluids (HPWBF) and Synthetic-Based Fluids (SBF). Results showed that evaluated drilling fluids were biodegradable and had low toxicity, indicating that can be used in offshore operations with low environmental risks.