Zipper Frac
In September 2014 the Journal
of Petroleum Technology’s Trent Jacobs reported that “hydraulically
fracturing and stimulating multiple horizontal wells in sequence has been
rapidly adopted by operators because of the potential for production without
introducing unwanted risks.” He was referring to the process of so-called
“zipper fracs” that had become popular. He noted that Marathon Oil first tested
the zipper method in the Eagle Ford shale in 2012. Zipper fracturing allowed
operators to shave days off of their well-completion processes, improving
efficiency and cutting costs. Zipper fracturing involves using a single crew to
alternate wireline and pumping operations between two wells resulting in more
pumping hours per day.
As shown below, different patterns of zipper fracs were developed, including alternating frac stages. Zipper fracs allowed operators to double the number of frac stages they could do in a day. They were also associated with improving initial production rates and estimated ultimate recoveries (EURs).
Jacobs wrote, describing the work of
Mukul Sharma, a professor and chair in the petroleum department at the
University of Texas at Austin (UT):
“When hydraulic fractures propagate into a formation, a stress shadow is created inside the rock that acts like a force field, hindering the fracturing of another stage. As the fracture closes, the spatial extent and the magnitude of the stress shadow is reduced.”
He went on to explain that Sharma thinks that unpropped
fractures are why zipper fracs worked so effectively. Allowing time for the
stress shadow to shrink by alternating stages between wells is believed to make
fracturing the next stage in the first well more effective due to the reduction
of stress interference from the previous frac stage in that well. The goal is
to stimulate the most rock and waiting for the stress field to shrink allows
more rock to be fractured.
Zipper fracs also added some
safety considerations with more high-pressure lines, extra equipment,
personnel, and fast-paced operations.
Neal Nagel, chief engineer and principal at Houston-based
OilField Geomechanics, noted that there are three primary factors that dictate
how well a zipper fracture may perform:
· Existence
and conductivity of the natural fractures
· The
impact the stress shadow may have on hydraulic fracturing between two wells
· Ability
to change the pressure within the natural fractures between two wells
It was also believed that the
Eagle Ford with its high degree of natural fractures was ideal for zipper
fracs. Nagel believed pore pressure was a key factor. The article goes on to
say that complementary technologies such as diversion technology which utilizes
diversion fluids as degradable bridge plugs that isolate the pressure in frac
stages, also help to make zipper fracs more effective both in saving time by
avoiding the need to run in and out of the hole to drill out the plugs, and in
improving production.
Simul-Frac
First done in 2016 and by
2020, a new fracturing method was coming to the fore, Halliburton’s Simul-frac.
In their 2020 brochure on Simul-frac Halliburton noted that like zipper frac a
single crew was utilized but the simul-frac “can help you achieve over
double the gains in lateral footage, in less time, compared to zipper-frac
operations.” Simul-frac involves working on more than two wells on a pad at
a time, like doing perforations on two wells while fracturing two of the other
wells. Even more so than zipper fracs, Simul-fracs require intense
coordination. The manifold or connection unit for multiple wells is very
important as Halliburton explains:
“The Halliburton ExpressKinect wellhead connection unit
(WCU) drastically reduces rig-up time and complexity, resulting in a more
efficient and safe operation. The ExpressKinect WCU eliminates up to 85 percent
of the high-pressure iron between the manifold trailer and the
wellhead. This unit also eliminates the need for zipper manifolds by providing
a single-line rig-up capable of reaching multiple wells and handling
120 bpm at 15,000 psi. This means that wellhead exchanges are executed in less
than five minutes, thus reducing rig-up complexity and improving cycle times to
drive increased efficiency.”
Halliburton also emphasizes their pump health monitoring
system and their simplified sand supply chain.
In February 2021, the Journal
of Petroleum Technology’s Trent Jacobs wrote about Simul-Frac, about 6.5 years
after he wrote about Zipper Frac. He first noted that the technique was
reducing time by half compared to Zipper frac, so huge time savings which means
cost savings as well. He noted that in the fourth quarter of 2020 about 8% of
operators were using Simul-frac. He noted that a Simul-frac requires 25% more
horsepower than a zipper frac. Thus, it was easy to identify with a little
detective work, who and how much of the industry was using it. The Permian
Basin became the epicenter of Simul-frac, where four-well pads, the ideal for
Simul-frac, were common. Other service companies aside from Halliburton were
providing Simul-fracs as well. A 2020 breakdown is below. Still, in late 2020,
about 78% of wells were using zipper fracs. Pads with four or more wells,
however, were beginning to upgrade to Simul-frac.
One issue that came up was
the need to have enough water and sand on location to feed the pressure pumps,
which could require more space and coordination. Jacobs noted:
“Simul-fracs also require splitting the pumping rates
between the wells, which means instead of 100 bbl/min, each well on the pad may
only receive 80 bbl/min. Rystad believes this is one reason why it has not seen
operators use the technique so far in highly overpressured and screenout-prone
formations such as the gas-rich Haynesville Shale.”
A June 2024 paper presented
at 58th U.S. Rock Mechanics/Geomechanics Symposium explored the attraction
effect of previously induced fractures, the effects of fracturing sequence, and
perforation arrangement. This would apply to both zipper and simul fracs.
“The results show that previously created fractures
exhibit a noticeable attraction effect on laterally created fractures, with
horizontal stress difference emerging as a pivotal factor. A lower horizontal
stress difference strengthens the attraction effect of previously created
fractures on laterally created fractures. During staggered fracturing,
laterally created fractures are simultaneously affected by the attraction
effect of previously created fractures and the extrusion effect of the adjacent
propagating fracture. Staggered fracturing of multiple perforation clusters
proves effective in enhancing the stimulation of perforation clusters and
achieving balanced fracture initiation and propagation. This research yields
valuable insights into fracture propagation, guiding and optimizing the design
and implementation of multiple staged fracturing in horizontal wells.”
A November 2024 paper in the
Journal of Rock Mechanics and Mining Sciences explored the fracture propagation
mechanism of multiwell fracturing, including completion sequence, well
placement pattern, well spacing, and cluster spacing. It also addressed
minimizing “frac-hits” where fracturing in one well overly effects fracturing
in an adjacent well, which can make the wells communicate via fractures too
much so that production is reduced.
“The results show that the completion sequence has a
critical influence on the stimulation effect and fracture geometry. From the
perspective of avoiding “frac-hit” fractures, fracturing the low-stress layer
can form an “artificial stress barrier”, which slightly protects the well from
interference from other fractures. The staggered well pattern is better than
the stacked well pattern. Compared with the stacked pattern, the staggered
pattern can reduce the overlap area of fractures by 80 %, which greatly reduces
the probability of “frac-hits”. With increasing well spacing from 200 m to 500
m, the fracture area increases by 25 %, and the degree of uneven stimulation
between the two pay zones also increases by 6 %. Considering that a small well
spacing is prone to “frac hits”, a large well spacing leads to an unstimulated
area between two wells, and a 350 m well spacing is optimal. The effective
fracture area decreases slightly with increasing perforation cluster spacing,
but the fracture geometry becomes much more regular. The results can be helpful
for the field design of multiwell fracturing.”
Chevron’s Triple Frac
In February Chevron announced
they would lay off 20% of their global workforce, another example of ‘downsize,
baby downsize.’ They noted in December 2024 that they will lower their 2025
capital spending by $2 billion, They also noted improvements in doing more with
less, including the new Triple Frac method.
“Through optimized pad and drilling designs and
completion improvements like triple frac, we’re able to achieve these
production levels with 40% fewer company-operated rigs than our plans included
just a few years ago,” said CEO Mike Wirth.
“In a “triple frac,” three wells are hydraulically
fractured simultaneously. Meanwhile, oil companies have also doubled the length
of lateral wells to three miles, and switching from diesel-powered equipment to
electric pumps has lowered costs as well.”
Chevron first deployed triple-frac in the Permian Basin in
March 2024 and ended up using it in 20% of their 2024 Permian wells. In April
of 2025, the company announced that it plans to use it on 50% to 60% of its
wells in the basin this year. They noted a 25% time savings and a 12% cost
savings.
“Triple-fracking requires the same amounts of sand and
water as fracking one well at a time, but uses them more quickly, meaning
Chevron needs 60% more water and sand per day when using the technique, Newhook
said.
“That creates a logistical challenge for sand and water
supply, with more than 10 trucks arriving per hour to deliver sand to the well
pad.
“The company has also begun fracking three wells at a time
in another shale field, the Denver-Julesberg basin in Colorado, Newhook said.
“Chevron uses mostly electric-powered equipment for
triple-fracking, which consumes 50% more power per day than fracking one well
at a time, he added.
“Triple-frac also requires more capital spending upfront to
have enough wells drilled in advance, Daigle said.
Matador’s Trimul-Frac, Including Remote Trimul-Frac
Another triple frac technique
is Matador Resources’ Trimul-Frac. Matador operates in the Delaware Basin part
of the Permian, in South Texas, and in the Louisiana Haynesville/Cotton
Valley. According to an October 2024 blog by Oilgas Leads:
“Following a successful trimul-frac pilot in Q2 2024,
the company expanded its usage with two additional trimul-frac operations in
Q3. One of these operations marked Matador’s first remote trimul-frac,
showcasing how remote fracturing can unlock new efficiencies by enabling
simultaneous operations across geographically dispersed wells.
Matador noted that while Simul-frac can save $250,00 per
well, trimul-frac can save $350,000 per well. It also saves time over
simul-frac, allowing wells to be put online faster.
References:
Simul-Frac
Gains Momentum in US Shale, Cuts Completion Times in Half. Trent Jacobs.
Journal of Petroleum Technology. February 8, 2021. Simul-Frac Gains Momentum in US
Shale, Cuts Completion Times in Half
Numerical
simulation on multi-well fracturing considering multiple thin layers in
vertical direction. Yunpeng Wang, Tiankui Guo, Ming Chen, Xuliang Jia, Dingwei
Weng, Zhanqing Qu, Zunpeng Hu, Bo Zhang, and Jiwei Wang. International Journal
of Rock Mechanics and Mining Sciences. Volume 183, November 2024, 105951. Numerical simulation on multi-well
fracturing considering multiple thin layers in vertical direction -
ScienceDirect
Sequential
Propagation of Multiple Fractures in Horizontal Wells. Tianyu Wang; Yuning
Yong; Jiaheng Zhai; Shouceng Tian; Xiaoxia Zhou; Mao sheng. Paper presented at
the 58th U.S. Rock Mechanics/Geomechanics Symposium, Golden, Colorado, USA,
June 2024. Sequential Propagation of Multiple
Fractures in Horizontal Wells | U.S. Rock Mechanics/Geomechanics Symposium |
OnePetro
Chevron
to 'triple-frac' half of Permian oil wells in 2025 to cut costs, time. Sheila
Dang. Reuters. April 9, 2025. Chevron to 'triple-frac' half of
Permian oil wells in 2025 to cut costs, time
Chevron
layoffs come as energy giant unlocks more crude with far fewer rigs in the
heart of the U.S. oil patch. Jason Ma. Fortune. February 14, 2025. Chevron is pumping more oil with
fewer rigs in Permian | Fortune
Simul-frac
operations double efficiency gains. Haliburton. Simultaneous fracturing
Reducing
Days on Location and Time to First Oil: Simultaneous Fracturing Operations.
Haliburton. 2020. 2020-MKTG-PES-11950_SimulFrac_Brochure.pdf
The
Shale Evolution: Zipper Fracture Takes Hold: Hydraulically fracturing and
stimulating multiple horizontal wells in sequence has been rapidly adopted by
operators because of the potential for production without introducing unwanted
risks. Trent Jacobs. Journal of Petroleum Technology. September 30, 2014. The Shale Evolution: Zipper Fracture
Takes Hold
Matador’s
Simul-Frac and Trimul-Frac: Revolutionizing Well Completions and Driving Cost
Savings. P Hinds. October 25, 2024. OGL
Oil Gas Leads. Matador’s Simul-Frac and Trimul-Frac:
Revolutionizing Well Completions and Driving Cost Savings – Oil Gas Leads
Matador
Resources Co: A Year of Record Growth and Strategic Expansion. Wesley Park. AInvest.
February 20, 2025. Matador Resources Co: A Year of
Record Growth and Strategic Expansion
Matador
Resources: Third Quarter 2024 Earnings Release. October 22, 2024.
Microsoft PowerPoint - Q3 2024
Earnings Release Presentation - October 2024 vFinal
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