Cat® G3600 A4 Solutions Lower Emissions Enabling Maximum Horsepower at Apache Sites

In September of 2016, Apache Corporation announced a new oil and natural gas discovery in the West Texas Delaware Basin region. Apache established a goal to build gas processing facilities and infrastructure required to process and compress the gas to market within nine months while minimizing emissions and the environmental footprint of its operations. Apache was able to meet the challenging site design goals utilizing Caterpillar’s latest G3600 A4 engine solution capable of 0.3g/bhp-hr NOx rating.

When the Cat® G3600 series engines were updated from A3 to A4, the hardware was designed to allow for a NOx rating of either 0.5 or 0.3g/bhp-hr.  To deliver these performance numbers, the engine controls were updated with the addition of technology leveraged from the G3500 engine platform. This included an engine exhaust mounted NOx sensor, providing closed-loop feedback control, allowing NOx to be actively monitored at the engine exhaust outlet. “With the A3 technology, we were indirectly monitoring through a system called combustion feedback so now with our A4 technology, it’s a direct control over engine-out NOx,” stated Bill Mermoud, market development consultant for Caterpillar Oil & Gas.

“We continue to meet the challenges of customers who require greater power density and lower emissions to achieve needed facility output,” said Mermoud. “Using NOx feedback gives us tighter emissions control over the engine which gets us to the 0.3g rating, allowing for a forty-percent reduction in NOx output for the same iron set. This is an unprecedented level of NOx emissions for a lean-burn engine,” said Mermoud. 

In addition, the G3600 A4 engine series was designed with improved air intake systems.  More efficient turbos contribute to allowing the engine to achieve increased air flow rates and higher intake manifold pressures required to achieve the lower NOx emissions. A new electronically controlled fuel valve was also added to the engine to provide more precise control, minimizing operating variability. “With the reduction of NOx emissions, our customers have the ability to increase installed engine horse power,” said Mermoud.

 Apache currently has three sites in operation, with additional sites under construction.  There are two different facility designs; the first includes five Cat G3606 A4 and three Cat G3612 A4 designed for 100 MMSCFD per day of compression and processing capacity and the second design of ten Cat G3612 A4 units for 200 MMSCFD per day of compression and processing capacity. 

 “Each facility design enabled Apache to simultaneously increase needed horsepower and lower air emissions at each site,” said Jim Virginillo, project manager at Apache Corporation. To learn more about the Cat G3600 A4 technology lowering NOx emissions by forty percent, be sure to check out the Gas Machinery Conference technology updates on Monday, October 2 at 1:00 p.m., or stop by the Caterpillar booth #524 during exhibit hours to meet the experts!

About Caterpillar Oil & Gas

Caterpillar Oil & Gas, Caterpillar Inc.’s oil and gas division with headquarters in Houston, Texas, consolidates all the sales and service activities for Cat oil and gas power solutions. Since the 1930s, Caterpillar has manufactured engines for the oilfield and today provides premier power solutions with outputs from 31 to 16,000 kW.  The sales and service network includes more than 2,100 dealer locations world-wide dedicated to support customers in the drilling, production, well service and gas compression segments. More information is available at:

About Caterpillar

For over 90 years, Caterpillar Inc. has been making sustainable progress possible and driving positive change on every continent.  Customers turn to Caterpillar to help them develop infrastructure, energy and natural resource assets. With 2016 sales and revenues of $38.5 billion, Caterpillar is the world’s leading manufacturer of construction and mining equipment, diesel and natural gas engines, industrial gas turbines and diesel-electric locomotives.  The company principally operates through its three product segments - Construction Industries, Resource Industries and Energy & Transportation - and also provides financing and related services through its Financial Products segment.  For more information, visit  To connect with us on social media, visit

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