Safe, Green Approach in Drill Cuttings Waste Mangement

Abstract

Innovative technologies offering safer and greener designs for handling and transporting hydrocarbon-contaminated drill cuttings are of great interest for offshore platforms. Traditional offshore mud skips require use of crane lifts that take up large areas of rig space and hinder continued drilling under inclement weather conditions. This paper describes a unique bulk transfer system that improves offshore cuttings handling safety and provides an environmentally acceptable solution to cuttings waste management and discharge requirements. The bulk transfer system consists of a single remote control panel unit, intermediate cuttings storage tanks, dual-pod pneumatic transfer unit, boat tanks with a logic control system, air compressor and an onshore hydraulic tipping mechanism. The unique drill cuttings storage with pneumatic transfer technology provides a means of storing drill cuttings in non-pressurized bulk storage tanks on an offshore rig. Cuttings are transferred in dense phase over long distances and heights to the boat storage tanks arrangement, enabling continued drilling over 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 drill cuttings properties. 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 over 400 feet at a rate of 20 to 35 Mt/hr 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 quick emptying system for faster turnaround times. When the boat tanks reach the waste management facility onshore, the drill cuttings are safely emptied by a specialized hydraulic tipping mechanism that is designed to tilt the tanks up to 85 degrees for optimized discharge. The bulk storage tanks total capacity of 320 tons (290 Mg) using (100 m2) of deck space. This bulk transfer technology enhances operational safety by significantly reducing the use of crane lift and minimizing environmental impact while enabling continuous drilling. The bulk transfer system also offers higher storage capacity, takes smaller floor space on the rig and enables mitigation of accretion or bridging in cuttings.