The evolution of U.S. shale E&Ps steering toward pad drilling and longer laterals has pushed service providers to innovate as they work toward optimizing completions.
Operators need oilfield service companies (OFS) to increase efficiency, consistency and reliability during hydraulic fracturing operations. NextTier’s secret: switch out drive mechanisms powered by diesel with drives powered by electricity.
During a Society of Petroleum Engineers’ Tech Talk, Kenny Jones, director of wireline technology and engineering at NextTier, explained how service providers are identifying safe, sustainable and differentiated technologies and value-added services to boost completion performance.
“The advent of longer laterals and multi-well pads associated with today’s shale operations have caused a shift in the way operators are using surface wireline equipment for plug and perf completions,” Jones said during a July 16 webinar.
On some locations, there are six wells on a single pad, creating a major shift in job scope.
“When you look at wireline for this type of operation, it's become strictly a pump down operation,” Jones said. “In long laterals, we are using fluid to pump and push the tool out in that lateral section so that you can set plugs to isolate the previous zone and do perforating holes into the next zone for optimized fracking.”
The frac operation becomes a continuous “zipper operation.” When operations are completed on one well, the wireline crew is able to start the next job without breaking down and moving the equipment to the next well. This enables continuous operation, which Jones said can be converted to 24-hour operations.
“So, we went from fracking four to eight stages in a week, maybe to as high as 16 stages per day.” So now we can keep the equipment on the same location for weeks, even months between pad moves. “It's a massive acceleration in efficiency,” Jones said.
Any downtime negatively affects the efficiency of operations. The operator’s expectation is that wireline shouldn’t disrupt the fracturing operation. NexTier’s goal is to produce a wireline system that stays out of the work-zone while ensuring that fracturing operations are continuous with zero interruptions.
The zipper frac has created a new set of challenges for OFS companies. NexTier is concentrating on three technology pillars to improve the multi-pad plug and perf shale completion process by:
- Improving electric drive equipment;
- Incorporate automation enabled operations; and
- Implementing enhanced digital connectivity.
Power up
Electric-driven field equipment is starting to improve wireline operations, Jones said.
In the past, OFS firms deployed a truck, a spooled chassis and a diesel engine to run the wireline. The setup was mechanical and easy to move from well to well.
However, with multi-pad locations now the rule, the mobility of a truck mounted system no longer offers a significant benefit.
The full electric winch is more efficient in terms of energy use. With the advent of electric fracking fleets, it makes sense for wireline operations to tap into the same grid at the location, Jones said.
“There's either grid power or some type of power generation system that they have set up for that frac fleet,” Jones said. Using electric drive equipment reduces fuel costs and increases operational efficiency.
“If no e-frac system is available, we can source electricity from a generator, which is a more fit-for-purpose power source,” Jones said. “There's very little wasted energy when the power source is right sized for electricity being consumed.”
NexTier has digitized its e-winch, which can now be run by an application specific software program.
“Operators can program the system to maintain target tension and speed, it’s essentially adaptive cruise control,” Jones said. “You can program in safeguards where there's an automatic torque limitation near surface or automatically close the tool trap at a certain depth. These advances enable the e-winch to rapidly respond to dynamic environments, making the system less dependent on human competency.”
Also, automation enabled pump down operations are using fluid to push the tool farther out in a lateral section. It’s a smart control system that can automatically achieve target rate with a simple touchscreen.
The technology is replacing the manual gear selection process to adjust RPM by a dedicated pump down operator. Automating the process has eliminated the need for a pump operator.
The system automatically optimizes engine performance and fuel economy, with “smart logic” accounting for engine health and transmission shiftability, Jones said.
“The automated pump down control system is very consistent with less variation from person to person. This translates into cost savings because operators are not using as much fluid during the run,” Jones said.
In one case, a swelled plug caused the e-winch to accelerate quickly. The automated system was able to recover without incident saving non-productive time (NPT) and additional costs of a lost tool.
‘Complete visibility’
Jones outlined additional benefits that digital connectivity is having on auxiliary wireline equipment, including control heads, the tool trap and the safety apparatus on pressure control equipment.
Previously controlled outside the recorder cap and run by various crew members, digital control systems enables a command center with a single point of control at heart of an operation.
“You get complete visibility of vital data that can be recorded and transmitted to NexTier’s hub for enhanced oversight,” Jones said.
Centralizing data eliminates multiple points of failure and optimizes running parameters, while reducing typical NPT drivers.
The e-winch and adoption of digital technologies have significantly reduced human-induced mistakes during wireline operations.
Jones said that even meaningful advances have been made, but he sees room for improvement.
“The statistics that wireline companies are publishing are just incredible compared to where we were in the past,” Jones said.