Tests on degradation of a new drill mud type under natural conditions

Abstract

Petrofree and Base Oil cuttings from offshore drillings were degradation tested in seminatural sea bottom ecosystem. dltrofree is a mixture of fatty acid esters. After 93 days the reduction in ester was significant and after 184 days close to 99%. Microbial degradation accounted for about 15%, while the rest probably was lost to the water as partly degraded metabolites. No significant loss was detected in the mineral oil cuttings, and biodegradation was less than 5%. Bacterial aboundance increased at both treatments. Petrofree degradation was clearly slow comparedto laboratory tests, but faster than the loss of the Base Oil.