System Provides Safe, Green Approach to Managing Drill Cuttings

Credit: Paper SPE 188738.
The typical rig storage-tank configuration consists of eight tanks with 320 tons total capacity using 84 square meters of deck space. A four-tank setup is shown here on a jack-up rig.

Safe and green innovations for handling hydrocarbon-contaminated cuttings are of great interest for offshore platforms. Traditional offshore mud skips require the use of crane lifts that take up large amounts of rig space and hinder continued drilling during inclement weather. This paper describes a bulk transfer system that improves the safety of handling cuttings offshore and provides an environmentally acceptable approach to cuttings management.

The bulk transfer system consists of a single remote-control panel unit, intermediate cuttings storage tanks, a dual-pod pneumatic transfer unit, boat tanks with a logic control system, an air compressor, and an onshore hydraulic tipping mechanism. The drill cuttings storage with pneumatic transfer technology provides a means of storing drill cuttings in nonpressurized bulk storage tanks on an offshore rig. Cuttings are transferred in a dense phase over long distances and heights to the boat storage tanks arrangement, enabling continued drilling throughout the duration of the well section.

The rig storage tanks include a self-emptying mechanism that generates full drainage, enabling continuous collection of cuttings until they can be pneumatically transferred to the boat storage tanks at variable discharge rates of up to 60 tons per hour, depending on the properties of the drill cuttings. The reduced height and footprint of this system optimizes space, while its improved efficiency enables reduced downtime in operations. The pneumatic blowing pump can move cuttings more than 400 ft at a rate of 20–35 metric tons per hour continuously to the storage tanks that are mounted on the support boat, enabling continued drilling in poor weather. The boat tanks are low profile and secured by ISO locks for safer navigation and a quick emptying system for faster turnaround times. When the boat tanks reach the waste-management facility onshore, the drill cuttings are emptied safely by a specialized hydraulic tipping mechanism that is designed to tilt the tanks up to 85° for optimized discharge. The bulk storage tanks have a capacity of 320 tons and require 100 m2 of deck space.

This bulk transfer technology enhances operational safety by reducing the use of crane lift significantly and by minimizing environmental impact while enabling continuous drilling. The bulk transfer system also offers higher storage capacity, requires less floor space on the rig, and enables mitigation of accretion or bridging in cuttings.

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