METHOD OF CONSTRUCTION OF OFFSHORE OIL AND GAS WELL WITH “ZERO” DISCHARGE OF DRILLING WASTE INTO THE SEA Russian patent published in 2018 - IPC E21B21/06 

FIELD: construction.

SUBSTANCE: invention relates to the construction of offshore oil and gas wells, in particular, to methods of handling drilling waste and protecting the marine environment from pollution. Method for construction of an offshore oil and gas well with a “zero” discharge of drilling waste into the sea is proposed, including towing and setting up a mobile drilling or stationary oil and gas platform at the point of the upcoming drilling in the sea area, crushing the riser into the sea bottom using pile-driving equipment, drilling out the rock from the cavity of the riser column with washing in a closed cycle without contact with the marine environment, accompanied by the formation and accumulation of drilling waste on the offshore platform, separate collection of drilling waste in inventory labeled containers and tanks on the offshore platform, deepening of the well inside the riser column with the washing in a closed cycle, accompanied by the formation and accumulation on the offshore platform of drilling waste, separate collection and storage on the offshore platform drilling and waste drilling mud in inventory labeled containers, separate collection and storing on the offshore platform of drilling waste water and the liquid phase of waste drilling mud, prepared on a water basis, in inventory labeled tanks, periodic evacuation of drilling waste from offshore platforms in inventory-marked containers and tanks using support vessels to onshore facilities for the disposal and disposal of waste, fixing, testing and development of the well. At the same time, the offshore oil and gas platform is additionally equipped with a complex of equipment for the sequential multi-cycle treatment of drilling waste during the construction of a well directly on the offshore platform, by sequential purification of drilling wastewater and the liquid phase of the spent water-based drilling mud by a physicochemical method using flocculants and coagulants, centrifuging the waste into solid and liquid phases. In addition, carry out the involvement of treated wastewater and the liquid phase of the spent drilling mud into the circulating technical water supply for the construction of the well, reducing the volume of fresh water consumption and drainage. Also carry out thermal deactivation of drill cuttings and the thickened phase of the spent drilling mud with their transfer to dry powdered inert material. Drilling wastewater and the liquid phase of the spent drilling mud are periodically evacuated after three or four cycles of their cleaning in inventory tanks to shore-based enterprises for disposal and recycling. Periodically evacuate neutralized dry powdered inert material in inventory containers to onshore facilities for disposal, moreover, the treatment and utilization of wastewater and thermal neutralization of cuttings and the thickened phase of the spent drilling mud are carried out on the offshore platform of pre-evacuation of waste on supply vessels to coastal enterprises.

EFFECT: reduction of labor intensity, volumes and cost of evacuation of drilling waste from the offshore oil and gas platform to onshore enterprises, reduction in the number of trips of tugboats and the risk of accidents with environmental damage in the process of well construction by utilization and disposal of drilling wastes directly at the place of their formation on the offshore platform prior to the evacuation of drilling wastes to coastal enterprises.

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