Hybrid solutions enable natural gas power generation for reliable, on-demand performance

Historically, drilling operations have relied on diesel and Dynamic Gas Blending (DGB) to supply the required power to the rig and ensure the capability to support the transient power load spikes seen in the drilling application, Fig. 1. The compelling cost and emissions advantages that running on field gas provides, compared to using diesel, is persuading companies of all sizes to implement gas-powered alternatives that not only deliver the reliability operations demand, but that also support ESG (Environmental, Social and Governance) goals. In many cases, this is a partnership that occurs among multiple stakeholders: supplier, contractor and operator. 

Fig. 1. Drilling operations traditionally have relied on diesel and Dynamic Gas Blending (DGB) to supply the required power to the rig and ensure support for transient power load spikes seen in drilling.

While natural gas power generation offers a superior environmental and cost profile compared to diesel, its historically slower responsiveness to transient power demand requirements has hindered its adoption for applications such as drilling. 

Solutions for natural gas power generation. The answer to this dilemma lies in the integration of multiple technologies to create a complete solution. Fully autonomous gas-hybrid systems use Cat’s latest controls technology, which fully integrates natural gas generators and energy storage to provide an optimized power solution to the operator. These systems, which are automated and optimized to efficiently power drilling rigs, can be retrofitted into existing rigs and future builds, enabling seamless operation. 

By leveraging the capability of this system, which includes the latest in genset controls, bidirectional power inverters and microgrid master controllers, operators can boost fuel economy and reduce engine maintenance and emissions. In the process, they increase uptime and capital efficiency. The result is exceptional performance in the field that provides operators the flexibility to run on a wide variety of fuel types that align with their strategic goals. 

Gas-hybrid systems can be powered by several fuel sources, such as CNG or LNG transported to the site; however, for drilling projects, the power source can be much simpler. Field gas can be directly connected to gas-hybrid systems to provide power that can be stored or delivered as needed. Not all gas is created equal, and some gas sources can have heavy hydrocarbons, which are of great value to the customer. These heavy hydrocarbons can be easily removed at the field level, to both provide a consistent flow of dry gas to the rig and return the NGLs back to customer operations. Providing an end-to-end solution allows operators to reap the full benefits of natural gas while ensuring the operational reliability critical to a successful drilling program. 

Gas in Colorado. A drilling site in the Mountain State demonstrates how far gas power generation has come in recent years. A supermajor operator sought to power their super-spec Helmerich & Payne FlexRig® (Fig. 2) with field gas, to lower emissions and operational costs. The plan was to use field gas, sourced from an adjacent pad, for drilling system power generation. While Cat could run directly from the field gas, the operator was advised that a more economical solution would be to remove the heavy hydrocarbons and return them before the gas was used for power generation. 

Fig. 2. A super-spec Helmerich & Payne FlexRig® was powered with field gas to lower emissions and operational costs for a supermajor operator. Helmerich & Payne’s experience deploying alternative rig power systems provided the customizable platform needed to achieve the operator's goals.

Caterpillar Oil & Gas designed an end-to-end approach to meet these needs. First, field gas was processed with Cat’s gas treatment partner, GTUIT, to remove NGLs and return them to the operator. The treated gas was then piped to a gas-hybrid system to run the super-spec rig. Multiple Caterpillar G3512 gas generator sets were integrated with energy storage to create a microgrid power supply. To optimize power supply to the rig, the system included the Energy Storage Solution (ESS), Fig. 3. This solution fully integrates lithium-ion batteries with Cat’s inverter and microgrid master controller, storing and discharging power, as needed, in harmony with the G3512s, to ensure an optimized power supply to the rig. Employing the microgrid master controller ensured the system worked together seamlessly to provide uninterrupted power, autonomously turning generators on and off as needed, rather than relying on manual controls. 

Fig. 3. The Energy Storage Solution (ESS) was part of the system that optimized power supply to the rig.

Historically, natural gas systems have not been optimized to ensure transient support in drilling operations, unlike diesel-powered systems. Cat’s gas-hybrid system, however, used energy storage and an integrated controls strategy to deliver optimized power for Helmerich & Payne’s operation. Additionally, incorporating gas treatment services transformed the NGLs from an inconvenience to a revenue stream, further improving the operation’s total economics. 

As with many new technological innovations, commitment was needed from all parties in the field. Helmerich & Payne’s experience deploying alternative rig power systems provided a customizable platform for the new technology. Several modifications to rig equipment were required, including VFD (variable frequency drive) skid modifications, recoding, rewiring and fine-tuning the power system to work with the FlexRig fleet design. This established a firm foundation to ensure successful communications and controls. 

A constant stream of communication was needed for successful implementation. Rapid response to change and commitment to the overall goal of the project created an environment conducive to continuous improvement and innovation. This was achieved through weekly meetings with all parties involved, reviewing data and capturing key insights as the project continued. 

Over the course of the drilling program, this end-to-end gas-hybrid solution produced significant reductions in regulated emissions, operating expenses, fuel costs and runtime. NOx emissions were reduced by approximately 80%, with CO2E reduced up to 11%. Using CNG reduced fuel costs by more than 30%, while using field gas saw an 85% fuel cost reduction. The integrated controls automation improved transient response while decreasing engine run time by up to 30%, supporting lower maintenance requirements and increased site safety.  Additionally, connecting the assets via Cat’s Remote Fleet Vision provided a continuous feedback loop and regular KPI analysis, to support the customer’s results reporting. 

The future of drilling. The oil and gas industry can benefit from advances in other sectors that also rely on complex equipment requiring reliable power. Since 2009, Caterpillar has been using key elements of this technology in construction and mining equipment, leveraging field-proven inverters, controllers and years of microgrid experience. This collective expertise informed the approach in Colorado, fostering a holistic solution tailored to meet the needs of the drilling operation. 

As ESG goals become increasingly important for oil and gas drilling contractors and operators both large and small, the need for custom solutions that allow for profitable gas-powered operation, the flexibility to use different types of gas (from field to LNG and CNG) and minimized environmental impact is even more important. For service providers, finding ways to provide flexible drilling solutions that can run on a range of fuel sources to align with customers’ KPIs is essential. 

Natural gas demonstrates clear advantages in terms of environmental emissions, costs and equipment footprint. Integrating automation, redundant capability and control mechanisms ensures that companies can achieve the operational effectiveness and efficiencies they seek. Companies looking to move to natural gas power generation for their drilling operations can improve their operational bottom line while maintaining exceptional performance, with end-to-end solutions that encompass these considerations.