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Shale’s lessons inform deep-water fracking

A new multistage fracturing service for ultra-deep completions saves rig time by incorporating tools for onshore unconventional reservoirs

Conventional multi-zone completion systems have several fundamental problems. They are time-consuming, costly, and treat only a small number of zones, which can lead to uneven coverage across the reservoir.

“Imagine the impact across the entire pay section if you can have 20 stages instead of just four,” says Jim Sessions, vice president for completions at Baker Hughes, a GE company (BHGE).

A new deep-water multistage fracturing service called DeepFrac from BHGE uses multi-position sleeves and flow-back control technology to rapidly stimulate more than 20 tightly placed stages, increasing reservoir contact with reduced rig time.

The new technology stems from a deep-water Gulf of Mexico operator request in 2016.

Jonathan Croy, sand control tools product line manager at BHGE, recalls one of the operator’s new project leads came from a land background.

DeepFraccropJonathanCroy  Photo: BHGE

"It’s not easy to do this offshore."
Jonathan Croy, BHGE
 

“Offshore, we’re doing these multizone frac packs. They’re complex and can take over a month using conventional tools, versus land, where we’re doing 40-plus stages in a matter of days.

"So, we began to think (about) why we can’t take a technology like that and use it offshore,” Croy says.

One of the difficulties lay in controlling the proppant at the reservoir.

“We had to figure out a way to access the formation to deliver the treatment and close off that access post-treatment, and then open up another access point for the oil while holding back the proppant we just placed down there,” he says.

“It’s not easy to do this offshore,” Croy adds, citing safety regulations, the need to control proppant, and the nature of the deep-water sector.

“The cost of intervention can be astronomical for some of those rigs. They typically aren’t set up for it.”

The DeepFrac solution brings together multistage completions tools for unconventional reservoirs and BHGE’s BeadScreen sand control technology, says Roy Woudwijk, product line director for lower completions.

“We had to combine many different technologies to arrive at the right solution,”

The integration of existing products resulted in a less complex system for deep water.

“This is about overall simplicity,” Woudwijk says. “We’re taking the complexity out of the deep water.”

“We couldn’t simply send the technologies offshore,” Sessions adds. “We had to make sure they were safe and compliant, and that they could minimise the need for interventions in this higher cost environment.”

DEEPFRAC Enabler: The DeepFrac service helps operators improve reservoir stimulation and coverage by enabling placement of multiple, tightly-spaced stages across an area that would typically be treated as a single zone.  Photo: BHGE
 

DeepFrac incorporates other BHGE products such as ball-activated sleeve technology and IN-Tallic disintegrating frac balls.

“Using the disintegrating frac balls means that production can flow without requiring coiled tubing to mill the balls out,” Croy says.

The BeadScreen flow-back control technology is used in the sleeves instead of a sand screen for sand control.

The bead screens are more erosion-resistant and have a higher burst pressure rating, which helps them withstand high flow rates over long periods of time, Croy says.

The cartridge looks like a puck with nickel alloy ball bearings welded onto the mesh screen for flow.

The technology can be run in both open and cased hole, he notes, but cost savings would be more significant in open hole completions by eliminating the need for casing, cementing, and perf runs.

Stepping stone

At present the system is limited to just over 20 stages. But “that’s the stepping stone”, Sessions says.

“We have a line of sight to an unlimited number of stages.”

The DeepFrac service has been deployed twice for a major Gulf of Mexico operator in water depths of more than 7000 feet (2134 metres).

The stimulations were at more than 25,000 feet total depth. In one of the deployments, the service saved 25 days of rig time and an estimated $40 million, says Sessions.

“It was the first-ever 15-stage deep-water completion,” he says. All stages were pumped in under 60 hours, reducing expenditures by 40%.

“It’s a significant step along the way to getting offshore wells online faster.”

The initial job was carried out in the fourth quarter last year in the Lower Tertiary, while the second took place in the first quarter of 2017.

The gap between jobs provided an opportunity for the completions team to refine its modelling and adjust its strategy.

For example, engineers were better able to pinpoint how much time it would take a dissolving frac ball to reach its target destination.

“By the time our second job came around, these balls were hitting the seat within seconds of our estimates,” Croy says.

The successful deployments did not go unnoticed by other deep-water operators, says Woudwijk.

“There is a lot of interest with different operators, and we’re following up on that. We expect more to come.”