Comprehensive Solutions to Drilling Waste Management

Abstract

Abstract ADCO has always been seeking continual improvement to minimise the impact of its drilling operations on the environment and to conserve the desert for future generations. One of the main challenges is proper management of the fluids & solids generated by drilling oil & gas wells. This paper presents the complete solutions adopted to handle the generated waste streams with the improvements in rigs design ("zero" discharge) and the execution of three recent plants:Reconditioning & recycling plant for drilling Oil-Based Mud (OBM).Indirect thermal desorption treatment plant for OBM drill cuttings with 100% recycling of recovered materials which are converted to usable products (i.e., diesel fuel, irrigation water and interlocking blocks).Two dedicated deep disposal wells for waste mud. The outcome of the joint efforts of Drilling & HSE Divisions confirms that all hazardous wastes are being managed with true applications of 3R (Reduce, Reuse and Recycle) to maximise hydrocarbon recovery without noticeable impact on the environment. The new waste management plants are centrally located in the major oil producing fields, thereby reducing hauling distance. These improvements translate in ADCO to minimum disposal and overall costs saving while ensuring compliance with or even exceeding, local environmental regulations. Such global approach of this scale is a first in the Middle East Region and is setting a new benchmark of environmental standards for others to follow. Introduction Drilling oil wells produce large quantities of solid waste drill cuttings and also fluids that must be properly managed to prevent negative impact on human health and the environment. The fluids comprised of drilling mud or brines used in each section of the well. The potential health and environmental hazards are fluids containing large amount of oil (diesel-based mud or OBM) or salts (high salinity water-based mud & completion brines). The solids are the cuttings removed from the hole. They do not present any hazards by their natural minerals but, if generated during drilling with OBM, they are contaminated by 20 to 30 % of oil, which require further treatment before final disposal. Currently, ADCO is producing an estimated 20,000 tons of oily cuttings and about 900,000 barrels of waste fluids have to be disposed off every year. Environmental legislation prohibits disposal of oily wastes into the environment. Waste Management Strategies For many years, ADCO Drilling Division has been increasingly confronted with problems relative to transporting oily cuttings over 300 km from the rig to a designated site for storage and disposal. Expensive OBM (diesel base) was reused few times at other rigs before injection into well annulus. The concept of zero waste discharges from drilling operations was being taken to new levels to develop zero contaminants discharge policy through implementing waste management principle of the three golden rules: REDUCE, REUSE & RECYCLE. The first move is to minimise as much as practical the amount of waste generated ("REDUCE"). Over the years, the following had been implemented in this regard:1. Reduce the hole diameter (less cuttings generated & less mud to be disposed off) by optimising the well casings program for every single well ("light casing program" whenever feasible).2. Eliminate the use of "emulsion" mud (oil added to WBM to reduce weight) in loss circulation zones by using "Aerated mud" (compressed air added to reduce weight).3. Improve the efficiency of the solid control equipment installed on the rigs ("state of the art" shale shakers and rented "Hi-G" dryers & centrifuges) to reduce the need for dilutions & limit the amount of oil on cuttings.4. Strive to reduce OBM usage by assessing & trying new inhibitive water mud systems (Silicate mud for example).