Summary

Deep well disposal of slurried drilling waste using a modified CRI process has been implemented at the Saudi Aramco Manifa Oilfield. Injection of drilling waste into a deep, high porosity, high permeability sandstone (approximately 6500 ft TVD) at Manifa began in 2012, and has continued with up to eleven disposal wells being active during drilling operations. To-date (April 2014), over 238,380 bbls of drilling waste streams have been injected. The modified CRI operations utilize a cyclic ‘slurry fracture injection’ process at high rates with direct-sand injection via dedicated disposal wells. Extensive process monitoring/analyses is used during CRI operations to ensure process control. The waste streams include drill cuttings, oil based drilling fluids, water based drilling fluids and brine. Deep well disposal provides a secure operation achieving ‘zero discharge’ by injecting cuttings and associated fluids. Skip and ship is used as secondary waste management method in case of limitations in CRI operations. The Khafji disposal formation was chosen for ‘slurry’ waste injection at Manifa field since it met or exceeded the desired criteria for permeability, porosity, depth and other properties. Injection takes place on drilling rigs and into dedicated disposal wells. Hydraulic fracturing is necessary to inject the slurry containing drilling wastes. As injection goes on, slurry design, injection strategy and dynamic formation geomechanics/fluid flow response will affect to the performance of the disposal formation. The use of modified CRI operations, using a cyclic, high rate slurry fracture injection process, is essential to ensure process control, maximize the formation storage capacity for these disposal wells/formations; and to ensure that the zero discharge operational-drilling objectives of the Manifa Drilling Team are met. This paper will present a field case assessment of the Manifa CRI operations performance in terms of achieving process control and meeting the zero discharge operational-drilling objectives of the Manifa Drilling Team by ensuring successful, reliable deep well disposal operations.

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