Deck drains, also known as "slop water" on offshore drill ships and platforms, can often contain drilling and completion fluids, solids and various hydrocarbons. These sources of contaminated water are mixed together and can be stored in a settling tank (also known as a "slop tank"). Other contaminants can enter the settling tank from the machinery space, from a non-machinery space or from other processing systems that contribute hydraulic oils, lubricants, solvents, grease and various solids. Oil separating and filtering equipment normally used onsite to process the slop water and reduce the oil content to less than 29 ppm or 15 ppm, depending on the regulations at the operation area. Hydrocarbons in slop water can differ from the hydrocarbons contemplated by Marine Environment Protection Committee MEPC 107(49). Anything subject to International Maritime Organization (IMO) MEPC 107(49) must meet a 15 ppm or 5 ppm requirement. A spill of solids can enter into the drains and then into the slop water storage tanks. Often, the tanks for slop water are mingled with bilge water storage tanks that are aligned with the space governed by MEPC 107(49), making anything that gets into the machinery space water subject to MEPC 107(49) testing and treatment requirements. Most IMO-certified oily water separators (OWSs) are not equipped to handle a full range of hydrocarbons or solids that are in the deck drain water and that are often difficult to define. The solids and free oils separate in the holding tanks, resulting in high concentrations of solids settled by gravity at the bottom of the holding tanks, high concentrations of oil floating on the top of the tank, and emulsified oil and water in the middle. When these high concentrations of oil or solids are fed to the OWSs; the systems are overloaded and the OWSs plug up. In some cases, offshore drilling operations are required to have independent offline testing of the water, even if there is an in-line oil content monitor with the system. In most cases, the recommended lab test by United States Environmental Protection Agency (EPA) uses either an EPA 1664A test (three different options) or an EPA 5520 test (six different options: B-G). This creates a problem because the IMO oil content monitors (OCMs) are certified based on the International Organization for Standardization (ISO) 9377-2:2000 procedure, which does not cover the same range of hydrocarbons. IMO-certified OCMs are not designed to measure hydrocarbons in the C3 to C9 range or above C38 because they are not required to be measured by IMO. Frequently, the independent lab tests produce a different result, usually higher than the OCM on the OWS, and the offshore drilling operation is not allowed to discharge overboard, resulting in significant cost. This paper describes a separation system specifically designed to handle the full range of contaminants that can be found in deck drain and machinery space effluent water. The system will separate oils, grease and other hydrocarbons from water in accordance with IMO standards as defined in MEPC 107(49). This separation system also offers greater removal of other hydrocarbons that are not included in the IMO standards. In addition, the system will remove high concentrations of drilling contents and other solids that generally plug up other water treatment systems. The system is adjustable so that each challenge can be addressed separately in an effective manner. The system provides a 0.02-micron positive barrier against most contaminants by using a back washable and low-pressure ultra-filter media. This system offers a processing rate of 45 gpm (higher amounts during rainstorms), requires a smaller floor space, enhances operational safety with fewer movable parts, and minimizes any environmental impact while enabling continuous drilling.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.