Image of Tartan’s patented MultiFrac™ Sleeve
Cemented wells with plug-and-perf completions is the go-to design in U.S. shale plays today, whether it’s in the Eagleford, the Permian or the Denver-Julesburg (D-J) Basin in Weld county, Colorado. However, this system has its limitations in extended-reach laterals which opens the door for the efficiencies of ball-drop sliding-sleeve tools in a cemented environment.
“In extended reach horizontals, it’s a time-consuming process to get the [perforation] guns in and out of the well. Also, the further you pump horizontally in a long lateral, the more operational problems you’re likely to get because the toe of a well is the most difficult part of the well stimulate,” says Dwayne DuBourdieu, Chief Operations Officer, Tartan Energy Group.
In February, a Colorado based independent operator working in the D-J Basin teamed up with Tartan Energy to overcome some of the limitations of plug and perf completions. The objective was to reduce costs and increase stimulation efficiency on a series of seven wells in Wattenburg Field to an average true vertical depth of 6,600 feet and an average total depth of 16,800 feet.
The producer’s goal was to use a cemented completions solution that leverages the efficiencies of a ball drop system while increasing limited-entry cluster efficiency compared to cemented plug-and-perf completions. Proving repeatable reliability was also a top priority.
Map of the Wattenberg Field in the Denver-Julesburg (D-J) Basin in Weld County
Design
“We worked with our customer to develop a hybrid cemented completions design using Tartan’s MultiFrac™ limited-entry system,” DuBourdieu says.
Each well comprised 31 treatment stages with three MultiFrac sleeves (clusters) per stage for a total of 94 sleeves at the toe. The upper portion of each well was completed with an average of 40 plug-and-perf stages. This hybrid completions design allowed a direct comparison of stimulation times between the MultiFrac and plug-and perf portions of each well.
Prior to the MultFrac cementable ball drop, technology was considered too unreliable to be a good fit for an energy company’s most challenging completion designs. Tartan’s patented BurstPoint technology allowed the sleeves to be completely closed off from annular contamination while cementing wellbores. This simple addition to sliding sleeve technology made it much more reliable for the first time and, therefore, made it relevant again in completion designs.
“Each casing string was floated into the well and two were rotated during installation, which highlights how easy the MultiFrac system is to install in extended reach horizontals,” DuBourdieu says.
Tartan’s patent-pending BurstPoint™ port technology
Results
The operator stimulated the first four of seven wells before spring breakup using cross-linked gel and slick water. Each of the 31 MultiFrac treatment stages was pumped using an average 260,000 lbs of proppant.
“Our portion of each well was stimulated in an average of 48 hours,” DuBourdieu says. “Based on how long it took to frac the top plug-and-perf portion of each well, our portion would have taken about 7 to 9 days to stimulate with plug and perf. So by using Tartan’s MultiFrac system, we were able to save our customer 5-plus fracking days per well,” he says.
DuBourdieu notes that Tartan MultiFrac not only reduced stimulations time by 60 per cent, that result was realized in the most challenging portion of the well to stimulate: the toe stages of an extended reach horizontal well. Moreover, MultiFrac, which incorporates BurstPoint technology, improved stimulation treatment placement and effectiveness.
“In a standard plug-and-perf operation, you have the charges explode and blow a hole through the cement casing into the formation,” DuBourdieu explains. “This leaves a hole that is rough and irregular. By using tools, we end up with a hole that is machined and very exact.”
Tartan’s BurstPoint holes are ringed by a hardened material that doesn’t allow that hole to erode as sand is pumped through it. The result is a more effective limited entry design, delivering cluster efficiencies upwards of 90 per cent throughout each treatment stage.
“We had no failures, no issues of any kind with our tools in this large sliding-sleeve install, DuBourdieu says. “Everything worked to design. Proving reliable and repeatable performance four times in a row was important in establishing our capabilities with this customer.”
The other 3-wells in the 7-well series are being stimulated after breakup.
Tracey Murray is Sales & Marketing Director of GridStone, a business growth firm focused on revenue generation for innovative companies. www.gridstone.ca
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