Drilling down operator costs onshore, offshore

With a well-publicized increase in drilling activity across the world, operators face a number of challenges. These include more complex wells, HP/HT related to drilling at greater depths, extracting the hard-to-reach reserves from mature areas, and the environmental sensitivities and regulations that affect E&P activity in the frontier regions.

In a climate where global demand for hydrocarbons is putting pressure on operators to increase their production schedules, economic factors are also driving more efficient operations.

TWMA technologies are designed to handle the treatment and disposal of drill cuttings. (Images courtesy of TWMA)

As a result of these factors, onshore and offshore drilling management practices are front of mind, with new technologies and advances in drilling muds and fluids allowing operators to optimize their drilling programs.

What is often overlooked at the start of the drilling campaign is the management of the solids produced as a result of drilling. Commonly described as drilling waste, this is perhaps a misconception since, with the right technology in place, many of the components in the mud can be reused back into the drilling process.

It can be argued that new challenges bring new opportunities, forcing companies to choose carefully with whom they wish to work and place enormous emphasis on innovative thinking and operational efficiency.

Waste management
In response to this, TWMA has been developing its TCC RotoTruck and TCC RotoMill technologies to provide a complete range of solutions for handling, treating, and processing drill cuttings and associated drilling wastes.

With expertise in managing drill cuttings and associated drilling wastes throughout their lifecycle, from initial production through all phases of handling, storage, and treatment to final reuse, recycling, or disposal, the company has developed its onshore and offshore processing technologies to provide operators with significant cost and time savings.

Processing drilling wastes offshore reduces the volume of wastes transported to shore; minimizes vessel logistics, truck transportation and crane and forklift movements; and provides a significant risk reduction in environmental impact.

Reuse, recycle, and reduce risk
The TWMA technologies are specifically designed to handle the treatment and disposal of drill cuttings. In the UK this process was put through its paces in a series of extensive offshore trials authorized by what is now known as the Department of Energy and Climate Change (DECC) to establish the effectiveness of the process in an offshore Oslo and Paris Conventions Commission (OSPAR)-regulated environment. The TCC RotoMill processes and recycles drilling wastes by separating them into their constituent parts of oil, water, and solids. The oil is recovered and can be recycled back into the drilling mud system, while the recovered water can be discharged or used as industrial water if required. The final solids can be disposed of according to local legislation governing non-toxic, inert substances or be used in industrial processes.

The technology can be used in any location, either onshore or offshore, at a rig site or central processing facility to effectively treat drill cuttings and associated drilling wastes at source. RotoMill is available in a number of variations, including truck-mounted TCC RotoTruck, skid-mounted or containerized for offshore operations, and bespoke solutions that have been developed for one-off applications. The units can be operated by a diesel engine or an electric motor of varying sizes and capacities.

The level of retained hydrocarbons in the solid phase is negligible, with proven results showing a concentration level of less than the OSPAR-regulated level of 1% by weight and well below the almost 7% currently required in the Gulf of Mexico. The water phase also has minimal oil content, again with proven results showing figures of around 15 ppm, while the recovered oil retains the same fingerprint as original base oil and is therefore suitable for reuse in the active mud system.

Treating drill cuttings and associated drilling wastes minimizes the environmental impact and, when used at source, eliminates the costs, environmental impact, and inherent safety risks associated with other methods of handling and treating drilling byproducts.

Integrating these solutions along with TWMA’s cuttings, collection, and distribution system provides drilling operators with a complete, efficient, and proven integrated drilling waste management package for oil and gas projects worldwide.

The RotoTruck in action
TWMA was contracted by an operator working in the Eagle Ford shale area of South Texas that had concerns about the cost and environmental impact of its drilling operations. This operator uses non-aqueous drilling fluid (NADF) to drill the challenging long-reach wells in this unconventional shale oil play. For waste disposal, drill cuttings and associated NADF were being transported to waste disposal sites some distance away.

TWMA mobilized a RotoTruck to the rig location to demonstrate its capability. The unit removed nonaqueous-based fluid from the cuttings outfall to a very acceptable < 0.3% average total petroleum hydrocarbon. This resulted in the unit being employed to service multiple operations, moving from well pad to well pad in line with cuttings outfall generation.

Over a period of six weeks, the unit processed 3,500 tons of NADF cuttings outfall, removing and recovering more than 3,000 bbl of nonaqueous-based fluid from the waste stream for reuse.

Along with the obvious environmental benefit, use of the technology has provided a financial bonus, recovering all of the nonaqueous-based fluid (99.5+%) from the NADF cuttings outfall, in this case worth more than US $450,000.

The recovered nonaqueous-based fluid contained little or no solids, representing 100% efficiency from material processed. Drying shakers, centrifugal dryers, and decanting centrifuges for drying are no longer needed; all nonaqueous-based fluid accompanying cuttings outfall was recovered by the RotoMill thermal process as clean non-aqueous base fluid.

With abundant caution, the recovered powder is transported to commercial disposal sites. In future applications, the plan is to gain landowners’ approval and bury the dry and relatively inert powder at site. This will eliminate cost, also reducing HSE risks and, in some cases, the security issues involved in transportation and disposal of wet NADF cuttings off site.

Technology evolution
Increasingly, these solutions have been engineered directly into offshore drilling operations. The benefits of processing drilling wastes at source include reducing the volume of wastes transported to shore; minimizing operations associated with skip and ship such as vessel logistics, truck transportation, and crane and forklift movements; and include a significant reduction in the risk of environmental impact from drilling operations. Increasingly operators are seeing significant cost savings by adopting a fully integrated drilling waste management solution that processes wastes at source.

To take the process a step further, waste management packages can be integrated into newbuild rig designs. As global environmental legislation evolves, operators are looking for rigs with integral waste processing capabilities offshore. Many longer term projects are making use of new, purpose-built units, and operators now have the opportunity to ensure that the onsite waste management equipment specifically matches the project requirements.