As the industry evolves to support oilfield companies’ sustainability goals, current dual-fuel solutions will enable drillers to navigate the industry’s shifting dynamics while keeping a competitive edge.
ANDY PUBLES, Caterpillar Inc.
Drilling contractors today face intense pressure to reduce OpEx and CapEx while also lowering greenhouse gas (GHG) emissions.1 As many fleets rely on existing Tier 2 diesel engines, fuel spend is one of the largest cost drivers on a drilling rig—and diesel price fluctuations can significantly impact drilling program economics. Companies striving to balance environmental regulations and corporate sustainability goals seek solutions that reduce GHG emissions without compromising performance or uptime. This conundrum poses a challenge for all drilling companies, Fig. 1.
FLEXIBILITY FOR TODAY’S DRILLING PROGRAMS
Lowering overall operating costs is an essential strategy for drilling companies, as it impacts profitability and competitiveness. As fuel costs are one of the largest expenses that a company incurs, optimizing fuel consumption can produce meaningful benefits. Several drilling companies blend natural gas with diesel to help streamline fuel use and expenses. Such dual-fuel systems not only promote cost savings but also help reduce GHG emissions simultaneously.
Technology has advanced in recent years, allowing natural gas to reliably power drilling rigs— especially in particularly demanding applications. The latest gas-blending solutions provide drillers the flexibility to increase field gas use when accessible and augment diesel use when the gas supply is restricted. This ensures continuous, dependable performance, regardless of location while curbing costs.
MAXIMIZING TIER 2 ENGINE INVESTMENTS
While optimizing fuel efficiency and reducing GHG emissions output may be compelling goals, the ability to limit capital spending is a key consideration. Technologies like the Cat® Dynamic Gas Blending™ Gen 2 Kit allow drillers to update current Tier 2 diesel assets cost-effectively, as an entire four-engine drilling rig can be upgraded for roughly the cost of a single new gas engine.
Such retrofits eliminate the need to modify a rig’s footprint or add complex new systems, as it seamlessly integrates into an existing engine package. By enhancing the life and capabilities of engines in the fleet, drillers can avoid stranded assets and realize a lower total cost of ownership.
This type of upgrade also maintains the power and transient capabilities that drillers typically experience with diesel engines, ensuring the ability to meet urgent needs imposed by sudden load changes and ramp-ups.2 This is a critical consideration on drilling rigs, where power demand can spike quickly.
Substantial diesel fuel savings are derived, as approximately 70% average diesel displacement (and up to 85% at peak) is possible with the kit – twice the diesel displacement capability of conventional dual-fuel technologies.3 At a 70% displacement rate, a rig that normally burns 100 gals of diesel per hour would only use roughly 30 gals of diesel for the same time period.
PROVEN IN THE FIELD
H&P, a major drilling contractor, experienced notable fuel savings in the Eagle Ford shale. Over a nine-month period, H&P saw an average diesel displacement rate of roughly 65%, with displacement peaking as high as 75% under optimal conditions.4 This saved over 94,500 gals of diesel on a single rig, with approximately 4,500 engine hours of operation, Fig. 2.
Every gallon of diesel saved resulted from the driller using natural gas in the form of field gas or compressed natural gas (CNG), which directly reduced fuel expenditures.
H&P benefited from an advanced port injection system that relies on multi-point gas injectors at each cylinder port for precise control of the air/gas mixture entering each cylinder. Cylinder pressure sensors and monitoring controls provided constant combustion data. Using this feedback, the engine’s electronic control module dynamically adjusted the amount of gas and timing of the diesel pilot injection for each cylinder in real time. This closed-loop control helped ensure the engine operated at the best possible combustion mix — maximizing gas use while stabilizing combustion. This produced diesel-like engine responsiveness with much lower diesel consumption.
Based on this experience, H&P intends to install additional kits on several additional engines in its FlexRig® fleet by the end of 2025.
ADVANCED ENGINE TECHNOLOGY FOR TOMORROW’S DRILLING NEEDS
The successful adoption of the latest dual-fuel technology for drilling applications signals a broader trend toward implementing advanced diesel displacement technologies in the oil field. As cost pressures mount, and GHG emissions standards evolve, solutions that enable drilling service providers to increase rig performance while optimizing diesel consumption will become increasingly indispensable.
It’s possible to retrofit today’s fleets to attain this improved efficiency at a fraction of the cost of new equipment. This empowers drillers to proactively meet evolving industry requirements and stakeholder expectations by reducing GHG emissions while delivering tangible fuel cost savings.
Drillers can expect further refinements and innovations in dual-fuel and GHG emissions-reduction technologies. Continued enhancements in engine control algorithms, fuel admission hardware and data analytics may produce additional diesel displacement rate possibilities to enhance fuel use in real time. The integration of intelligent energy management systems with high-displacement dual-fuel assets offers a glimpse of the rig of the future—one that automatically optimizes the gas-blending ratio and reduces GHG emissions without crew intervention, Fig. 3.
As the industry evolves to support oilfield companies’ sustainability goals, current dual-fuel solutions will enable drillers to navigate shifting the industry’s dynamics while keeping a competitive edge. WO
REFERENCES
Cat.com. Caterpillar oil and gas announces launch of Cat® Dynamic Gas Blending™ (DGB) Gen 2 Kit. February 2025. https://www.cat.com/en_US/news/engine-press-releases/caterpillar-oil-and-gas-new-cat-dynamic-gas-blending-gen-2-kit.html
Cat.com. DGB by the numbers [Blog post]. https://www.cat.com/en_US/blog/dgb-by-the-numbers.html
H&P. H&P introduces Cat® Dynamic Gas Blending™ (DGB) Gen 2 Kit by Caterpillar Oil & Gas. https://www.hpinc.com/resources/news/hp_cat
ANDY PUBLES is the Drilling and Completion product manager for Caterpillar Inc. He has worked at Caterpillar for over 16 years and has extensive experience in multiple engineering functions, product strategy and development, with a focus on integrated systems. In his current role, Mr. Publes provides leadership for product strategy and development, as well as application and installation engineering for products used in Drilling and Well Services. He holds a B.S degree in electrical engineering (Power Systems) from Michigan Technological University and an M.S. degree in electrical engineering (Controls and Integrated Systems) from Bradley University.