Testing Of Highly Paraffinic Crude Oils For Toxicological Effect And Chemical Dispersibility
Authors: Smith J.P. , Wardrop J.A. , Seignier M.R. 
Published: October 2008

This paper presents the findings of in-depth chemical testing and toxicity testing of medium gravity highly Paraffinic crude oils on tropical and temperate environments. Reviewed are temperate water EPA LC50 testing, EPA LC50 testing modified to tropical waters, chemical analysis for water soluble fractions and dispersant effectiveness testing. Toxicity testing was conducted on crudes, dispersants, and crudes plus dispersants to ascertain implications of immediate biological effect and habitat disruption.

These data provide a preliminary database for crude toxicity in tropical waters and definitive dispersibility data on paraffinic crude oils in temperate and tropical waters. Data on available water soluble fraction present in paraffinic crudes is compared with observed water soluble fractions found in the water column. Crude dispersibility for temperate and tropical, conditions are presented. Finally, the implications of these data to biological impacts is reviewed.

INTRODUCTION

Pertamina/Maxus southeast Sumatra, Inc (Maxus) operations are located within the Mining Contract Zone (WKP) designated as the Southeast Sumatra Contract Area. Exploration began in February, 1970. Since that time, total drilling activity has expanded to include 189 exploratory wells, 194 delineation wells and 379 development wells over the leasehold. All Maxus SES facilities are offshore on the Java Sea side of the Sunda Straits North of the Island of Java and Southeast of the Island of Sumatra. The concession covers an area of 13,72S square kilometers and encompasses or adjoins to the Thousand Islands, a resort area and a National Marine Park. Maxus commissioned in February 1993, a series of studies to assess the behaviour and toxicity of two Maxus crude oils, "Widuri" and "Cinta", during spill conditions. These studies were designed to assess the physical and chemical behaviour and toxicity of fresh and weathered crude oils with and without the application of a range of commercially available dispersants. The Laboratory Studies were divided into three components;Chemical Characterization Studies, which include:–The Oil Dispersant Efficiency Study that examined the efficiency of dispersants on the crude oils, and also included studies of the fate and effects of each crude oil.–The Oil Dispersant Analytical Study Program which examined the chemical character of fresh and weathered crude oils, treated oils, and Water Soluble Fraction (WSF) beneath all the above.Toxicity studies, which included :–Standard US EPA Toxicity Tests for temperate marine species, and–Modified EPA Toxicity Tests for tropical marine species.Synthesis and ReportingThe Laboratory Studies were in turn part of a larger study known as Environmental Study on Sensitivity and Characterization of Crude Oil (ESACOC) (l).

Other aspects of the ESACOC study were:Spill risk assessmentCoastal atlas preparation,Sensitivity mapping;Oil spill trajectory modelling; andGeographic information system development.

Two export oils were studied during these tests they are;Cinta export crude oil;Widuri export crude oil.

Both oils am highly viscous and mostly solid at ambient temperature due to their very high pour points. Characteristics of each oil is noted below,