Declining oil prices and low oil recovery rates have put refracturing on the minds of companies operating in shale plays.
“E&Ps are no longer on a treadmill. They’re reassessing whether drilling and fracking new wells are the right way to go and whether it may be more advantageous to engage in refracking,” James Coan, senior consultant for IHS Energy, said May 20 during a webinar.
However, the practice of refracturing—mostly used in the Bakken, Barnett and Marcellus—remains low overall, accounting for less than 1% of the overall hydraulic fracturing market today, according to Christopher Robart, managing director, for IHS Energy. The percentage could rise by 20% in the coming years, as companies chase opportunities to unlock new production.
But challenges and concerns exist.
“The candidate selection process can be quite challenging,” Coan said. “Determining candidates involves looking at the wells themselves, but also looking at the wells nearby.”
Typically, E&Ps have targeted their best performing wells for refracturing, rather than low producers or wells that were initially fracked poorly, he said. Factors that usually support refracturing a well, IHS said, include:
- Large gaps between the original fracture and fracture techniques such as stage spacing and proppant loading.
- Geological indications of high performance such as high TOC, thick reservoirs and high porosity and permeability.
As for the impact of neighboring wells, thoughts are that strong producers could be indicative of productive geology nearby. “However, such a connection is not straightforward,” because fracks between wells could be interacting with each other, with neighboring wells draining resources from the target well, according to Coan.
Refracks are generally more effective if they target new rock and for now, oil instead of gas, he said. “In order for refrack to succeed, the most important step is for an E&P to begin a large-scale refrack program” to find the best methods.
Each refracking method has its own benefits and drawbacks.
Using diverting agents to plug fractures or perforations, the most common method, is the least expensive; however, they target the entire wellbore making it difficult to control which frack is addressed, Coan said.
There is better control with the CT frack method where resettable packers target fracks. But there is concern about how well the packers work in containing the frack and the flow rate.
Mechanical isolation allows for a new wellbore, but that means a new—and expensive— liner is required.
Refracking costs might give some E&Ps pause, given today’s lower price environment.
But the expense could pay off if the technique leads to production growth.
Those looking for detailed answers, such as which well parameters are most likely to lead to success, how much increased production is required to justify refracturing expenses or specifics on current refracture operations, will have to wait until June when IHS Energy releases an in-depth analysis. The webinar provided a glimpse into what the report will offer.
There is a lot of upfront work involved in not only identifying appropriate candidates for refracturing but also the custom engineering for designing refrack operations, Robart said.
“The fact that E&Ps are going through this process now and preparing themselves to do refracks means that if the oil price were to increase a little bit they would be prepared to take advantage,” he said, noting some E&Ps would instead opt to keep drilling new wells.
The economics of refracking depend on several factors, including the method chosen and size of the refracks, Coan said.
“The most important factor to get this off the ground is for E&Ps, particularly service companies, to make large investments to test this,” he said. “Who is going to be the George Mitchell of refrack?”
During a conference call April 20, Halliburton president Jeff Miller said the refrack economics are attractive for Halliburton and its clients. The company has diverting technologies that specifically address refracking such as AccessFrac stimulation service. The process, which targets cluster completion efficiency and cluster production efficiency, aims to help optimize proppant distribution for better production performance, the company said. Other technologies seek to identify the best candidates for refracking.
Schlumberger also recently touted its refracking success with its BroadBand Sequence technology. The key enablers are the ability of subsurface experts to identify the right well candidate and the technology, in this case BroadBand Sequence, to divert fracturing fluid into the perforations that haven't properly been fractured in the first place, Schlumberger CEO Paal Kibsgaard explained in a conference call April 17.
The technology was used at one of Pioneer Natural Resource Co.’s previously fracked horizontal shale wells in the Eagle Ford. The well’s oil and gas production increased by about 120% and 89%, respectively, during the first 45 days after refracking, the company said.
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