Reduction of Salinity Concentration in Synthetic Oil Based Drill Cuttings for Unimpaired Environmental Disposals

Abstract

Drill cuttings which comprises of water based cuttings and synthetic oil based cuttings are all oil & gas associated drilling wastes consisting of chloride, heavy metals and oil & grease which are classified as hazardous wastes with inherent high density hazardous and challenging environmental effects, hence absolute mitigation of the environmental impacts with respect to effective treatment of the wastes in line with regulatory approved environmental disposable limits become a necessity and a surmountable environmental challenge. Several treatment concepts were being experimented but none is yet to proffer appreciable and acceptable level of treatments for inherent salinity with respect to regulatory approved minimum disposal limit of 600ppm. Some of the explored treatment concepts for reduction of salinity concentration in drill cuttings includes but not limited to drill cutting incineration, drill cutting slurrification & re-Injection, thermal desorption unit, etc. Salinity is assumed to be hazardous to the environment at above regulatory disposal values of 600ppm for land and 2,000ppm for offshore as several factors could be attributed to some of the current inconsequential and unsuccessful treatment concepts. Emphatically, the use of thermal desorption unit for the treatment of synthetic oil-based cuttings is observed to be limited to optimized recovery of oil and grease at a maximum heating temperature of 510oc which is absolutely inadequate for thermal decomposition of inherent salinity whose melting point is observed at 801oc. A total number of three (3) synthetic oil drill cuttings samples were collected from Agbada 45, Serex 12 (Soku 51) and O.E.S. Passion with pre-treatment laboratory values of 86,200ppm, 52,305ppm and 21,000ppm and were subjected to about twelve (12) heat treatment modules with corresponding post-treatment laboratory result of 440ppm, 240ppm, and 700ppm respectively, the results were observed to

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