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In 1990's due to lack of treatment facilities, Oil Based Mud (OBM) drill cuttings generated from drilling operations were dumped in an interim waste storage facility located in prime industrial area. Considering the complex nature of hazardous waste on land, treatment costs and future environmental liability involved, company evaluated number of treatment options and based on techno-economical and legal assessment, selected option of transferring OBM cuttings stored in pits for treatment using Thermal Desorption process. Thermal desorption is recognized as best environmental remediation process that uses heat to increase the volatility of contaminants to remove hydrocarbons and water from the solid matrix. The storage pits were remediated by removal of bottom contaminated soil upto 1% Total petroleum Hydrocarbon (TPH) and HDPE Liners. The treatment of legacy waste including clean-up of the old pits enabled site decommissioning for future industrial expansion in the area. The successful completion of project resulted in considerable economic benefit compared to other competent treatment costs and reduced environmental liability from legacy wastes. The paper presents the methodology adopted for treating OBM legacy waste and clean up of the site confirming to regulatory requirements.

Water is crucial for oil and gas production and typically used for crude washing, drilling mud preparation and accommodation facilities. Water resources in UAE are scarce due to low average rainfall and high evaporation rates. Ground Water is over exploited and consequently the productivity of the aquifer was adversely affected[1]. The water shortage issues have a potential to threaten the sustainable development and hinder national plans for human, industrial and agricultural development[4]. ADNOC Onshore investigated number of technologies and opportunities to recycle wastewater. Upon conducting compatibility and modelling studies, it was established that ADNOC gas processing plant treated wastewater can be safely utilized for crude washing purposes and drilling mud preparation. The paper presents the methods adopted by ADNOC Onshore to evaluate the scaling effects, laboratory tests conducted to assess the suitability for crude washing, mud preparation and potential benefits by utilizinggas plant effluents.

Managing environmental impacts associated with drilling is a challenge to oil & gas ompanies and in recent year more efforts are exerted in increasing production levels hence increasing drilling activities and associated environmental concerns. Key environmental issues associated with onshore drilling activities include release to the atmosphere & groundwater and generation of hazardous wastes. Over the last few years, ADCO has intensified its drilling activities to meet challenging production targets and over the last 10 years number of drilled wells has almost doubled. In order to minimize environmental impacts of drilling activities addressing environmental issues became central to work planning and regarded as a business objective. The majority of drilling wastes includes drilling fluids & cuttings and if these are not managed effectively they may result into soil & groundwater contamination and could harm to biota. In order to minimize the environmental impact of drilling waste an integratedwaste management scheme was developed to implement Zero Discharge and 100% HSE concepts from drilling locations and this scheme includes: Two waste disposal wells for Water Based Mud (WBM) for injection in the deeper aquifers. Reconditioning of Oil Based Mud (OBM) at reconditioning plant for reuse Thermal Desorption Unit (TDU) for treating OBM Cuttings In 2017, approximately a Million feet of wells were drilled resulting in generation of 200,000 tons of WBM cuttings and 40000 tons of OBM cuttings. OBM Cuttings were treated at TDU and 12000 bbls of oil was recovered. In addition, approximately 100 K bbl. of waste WBM and other drilling fluids were injected in deeper formation. 99.9% of oil from OBM cuttings is reclaimed as a fuel and the final inert material used for manufacturing cement blocks. The outcome the solution is converting drilling hazardous wastes through 100 % recycling into environmentallyfriendly and beneficially-used products. The concept of 3Rs- Reduce, reuse& recycle is applied for managing drilling waste to protect the environment.