Laboratory Assessment of Biodegradation of Non Soluble Drilling Mud Base Fluids Under Nigerian Environmental Conditions

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn Nigeria today, the environmental acceptance of a non watersoluble drilling mud base fluid depends not only on its toxicity as measured from traditional bioassays, but also on its biodegradation under aerobic and anaerobic conditions. Presently, however, there is no widely accepted laboratory method for biodegradability assessment of drilling fluids.Based on its relevance to environmental conditions affecting the biodegradation of drilling fluids, the recently developed Solid Phase Biodegradation Test Method was chosen for assessment of drilling fluids in Nigeria. The test was modified, essentially to ensure better simulation of Nigerian environmental conditions. Thus, the Nigerian version of the method is a 60 day "closed system" Test that entails the assessment of a given sample in both fresh and brackish/marine water simulated environmental conditions. The biodegradation assessment of three drilling fluid types: an ester, an olefin and a mixture of both was carried out using the Nigerian version of the Solid Phase Test. The results obtained are presented in this paper. They compare favorably with and validate other Solid Phase Test results, which show olive oil to be a ready degradable substance and esters as having a generally higher percentage degradation than other synthetic base fluids. In this test, percentage biodegradation was observed to be higher in the brackish/marine water than in the freshwater simulated environment.

Developing a Thermally Stable Ester-Based Drilling Fluid for Offshore Drilling Operations by Using Aluminum Oxide Nanorods

“…It has been recognized that esters that are derived from plant oils provide the best environmental performance out of the SBDFs. The emission of organic vapors from them is minimal relative to linear alpha olefins LAO and isomerized olefins (IO), and they undergo full biodegradability in both aerobic and anaerobic conditions [9][10][11]. When addressing biodegradation, bioaccumulation, lubricity, and eco-toxicity, EBDFs are also superior to other SBDFs; therefore, they are considered the best environmentally friendly options for drilling fluids.…”

Laboratory Assessment of Biodegradation of Non Soluble Drilling Mud Base Fluids Under Nigerian Environmental Conditions

“…Additionally, all non-water drilling mud base fluids are required to undergo biodegradability testing under Nigerian environmental conditions as a permit requirement for their use in Nigeria 6 . In the absence of a standard and widely accepted method for biodegradability testing, and based on review findings 8,9,10 on existing methods, the recently developed Solid Phase Biodegradation Test was selected for application in Nigeria. The relevance of the method to environmental conditions affecting discharged drill cuttings impregnated with non-water drilling mud base fluids was the primary consideration in its selection.…”