For more than 60 years, hydraulic fracturing has helped bring oiland gas to the surface from wells that otherwise would be clas-

sified as uneconomical. Currently used in an estimated 90% of allland-based wells in North America, hydraulic fracturing willremain a mainstay in the operator’s bag of tricks, as development oflower-quality reservoirs becomes the rule rather than the excep-tion. Worshipped by some and feared by others, fracture stimula-tion technology continues to evolve to better meet the needs ofproducers and environmentalists, not only in North America, but

on a global scale.“We are beginning to see the increase in the focus on unconven-

tional developments in many areas of the world outside of NorthAmerica, such as Argentina, Eastern Europe, China, and the MiddleEast,” said Ted Lafferty, vice president of stimulation services,Schlumberger. “Currently, due to higher prices of oil, we are seeing amoderate shi in activity in North America from the dry gas reser-voirs toward the reservoirs that have more liquid content (condensateand oil), like the Bakken and Eagle Ford. Unconventional reservoirsrequire hydraulic fracturing to be economic today, so the advances infracturing technology have contributed to making some of the keyactivity areas today viable that would not have been economicallyviable even 10 years ago.”

As the use of fracture technology increases, “one size fits all” nolonger applies, and ongoing technology development is the name ofthe game. Today’s drillers perform sophisticated analyses of formationproperties from core samples taken from individual wells to deter-mine the precise formulations of the frac fluids needed, workableproppant-fluid-pressure combinations, and ideal frac orientation.Proppants now come in a variety of formulations, shapes, and sizes,each with their own advantages and disadvantages, and partial mono-layer technology is evolving so that one layer of sand can offer the sameconductivity as 10 layers of proppant.

Fracture treatments now use high-resolution seismic to deter-mine natural fault locations in shales so that the man-made frac-tures reach those crucial pathways, or, alternately, to avoid thosenatural faults or karsts that will suck the life out of the productionstream. Microseismic and tiltmeter mapping can relay frac infor-mation in real time so that geohazards are avoided and the maxi-mum reservoir area is accessed successfully. Additionally,fracmapping services have been used to confirm that hydraulicfracs do not grow so far out of the target zone as to contaminateaquifers and surface water resources. Kevin Fisher, general man-ager of Pinnacle, a Halliburton service, points to data from thou-sands of fracs in the Barnett, Marcellus, and Woodford shales

Hydraulic FracturingGame-changing advances in

stimulation and production technologyare improving well economics.

OVERVIEW

By Kelly Gilleland, Contributing Editor

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OVERVIEW

where Pinnacle’s microseismic mapping services verify fractureheight containment with measurements showing they remain amile or more below any potable water sources.

Environmental stewardship has given rise to a plethora of newfluids technology, including new drilling mud and fracturing fluidformulations, and it has also spurred such innovations as the devel-opment of a portable closed-loop system for recovering reusableoil-based fluid. New water-based drilling fluids have been used suc-cessfully in shale plays such as the Haynesville, which has the dualchallenge of extremely high bottomhole temperatures, and inCanada’s Bakken Shale, where a crosslinked fracture fluid thatworks with flowback and production water is being used success-fully. ermal evaporation systems to treat and reuse frac water arebeing developed and tested, providingnot only ecological benefits but costsavings as well.

CChhaalllleennggeess aanndd ssoolluuttiioonnssEven with all the advancements instimulation and production technol-ogy, the industry still faces challengesregarding fracturing operations. Onespecific challenge, Lafferty said, is inthe efficient optimization of the num-ber of frac stages to maximize per-formance of the horizontal well.“Increased use of production logs is stillrequired to provide a quantitative eval-uation of the performance results ofvarious technology and processchoices,” he noted.

Fracturing can comprise a significantpercentage of total well completioncosts, so getting an optimal stimulationtreatment is critical to the success of theprogram. Nearly all fracturing takesplace in low-permeability rocks such astight sands and, increasingly, shale,which comes with a set of operationalchallenges beyond the frac procedure.And even if a company successfullyfinds and manages to produce signifi-cant quantities of hydrocarbons fromsuch reservoirs, environmentalists andother energy industry outsiders con-tinue to look at fracturing as a highlysuspicious activity.

“One gentleman I spoke to com-pared fracing operations to a wholeslew of government-related conspir-acy theories like hiding aliens in Area51,” one geoscientist said. “I’m not

sure how fracturing got so mysterious – I guess because it hap-pens downhole and you can’t see the effects from the surface –but the whole fear of fracturing being the source of groundwa-ter contamination is really a non-issue.”

To combat the allegations, several companies are disclosinginformation about the makeup of their frac fluids. Halliburtonnow is providing the public with information related to the iden-tity and common uses of the additives and constituents generallyinvolved in the hydraulic fracturing process – additives that typ-ically comprise less than one-half of 1% of the total water-and-sand-based solution.

“Halliburton has just made available new web pages to empha-size our forthright disclosure of the additives and constituents that

Service companies expect the increasingly intense scrutiny by regulators and the publicto lead to hydraulic fracturing operations on smaller locations, with less traffic on sensitivelease roads and with more environmentally responsible fluid systems. (Photo courtesy ofBaker Hughes)

are used for several typical wells in Pennsylva-nia,” said David Adams, vice president of Hal-liburton’s production enhancement productservice line. “We believe this effort representsan important and substantive contribution tothe broader long-term imperative of trans-parency.”

While the initial focus of the additive disclo-sure pages are limited to activities taking placein Pennsylvania, where development of the Mar-cellus Shale already is well under way, Hallibur-ton said it is committed to continuing to providehydraulic fracturing fluid disclosure informationfor every US state in which the company’s frac-ture stimulation services are in use.

Public concerns about oilfield safety and wateruse are driving regulators’ interest in hydraulicfracturing, which increases operators’ interest inminimizing HSE footprints. “Even for com-pletely benign fracturing fluid systems, the layersof pre-job disclosure and extensive testing anddocumentation will change the process of frac-ture planning and operations,” said Lindsay Link,Baker Hughes’ president for pressure pumping.

Even as fracturing experts address concernsabout the relatively small volumes of chemi-cals pumped downhole in hydraulic fractur-ing, well cementing will become increasinglyscrutinized for its ability to isolate water andhydrocarbon zones.

“Cementing will necessarily become linkedwith safe, effective hydraulic fracturing, so engi-neers will design cement systems that not onlyachieve good bonds, but also control gas migra-tion control and withstand stimulation and geo-logical stresses expected for the life of the well,”Link said.

Service providers are not the only ones readyto talk about fracs, although some argue this isjust a thinly veiled effort to head off tighterscrutiny and federal government regulation. Inearly 2010, ExxonMobil announced it would bewilling to disclose what chemicals were beingused in its wells across the US. According to afiling the company made with the SEC, “Exxon-Mobil supports the disclosure of the identity ofthe ingredients being used in fracturing fluidsat each site. While we understand the intellec-tual property concerns of service companieswhen it comes to disclosing the proprietary for-mulations in their exact amounts, we believethe concerns of community members can be

OVERVIEW

Figures 1-3 show Pinnacle fracmapping data on all fracs mapped in the pastdecade in the Barnett, Marcellus, and Woodford shales. The frac top and bot-toms are shown and sorted from deepest to shallowest completions in these threereservoirs. The frac top and bottoms are contrasted with the deepest aquifers inthe counties where the fracs occurred as listed on the USGS website. (Imagescourtesy of Pinnacle; data source: USGS)

Barnett Mapped Frac Treatments/TVD

Marcellus Mapped Frac Treatments/TVD

Woodford Shale (OK) Mapped Frac Treatments/TVDs

OVERVIEW

alleviated by the disclosure of all ingredients used in these fluids.”To help alleviate the confusion, hydraulic fracturing companies

are not only ramping up their press campaigns, they are enhancingtheir product lines. Fisher said the fracing sector is making hugestrides in filtration methods as well as formulating safer fracturingchemicals. “ings are safer now than they were five years ago,” hesaid. “I think all of the operating companies are extremely safety-cognizant these days, and not just because safety and environmen-tal issues are regulated.”

Halliburton recently announced a new line of frac fluids calledCleanStim that are composed entirely of food-grade chemicals.CleanStim, an integral part of the company’s new CleanSuite lineof products, is the first fracture fluid to source its componentsentirely from the food industry.

“e safe and efficient use of this technology has never been moreimportant or in greater demand than it is right now,” Adams said.“With the CleanSuite line, we believe we’ve effectively set a newstandard for how unconventional resources may be accessed andproduced in the future.”

e line is composed of: • CleanStim fracturing chemicals; • CleanStream, a service that uses ultraviolet light instead of

chemical additives and biocides to control bacteria that canblossom and kill well conductivity and cause viscosity insta-bility in fracturing gels; and

• CleanWave, a wellsite wastewater treatment system that allowswastewater to be reused and recycled by the operator, signifi-cantly reducing the need for freshwater.

“Halliburton is a recognized industry leader, and takes safety andthe environment very seriously,” Fisher added.

Schlumberger also has prioritized safety in its operations andtechnology development. “We have introduced many advances thatimpact our ability to keep our operations and our people safe,” Laf-ferty said. “Some of these have come in the form of equipment mod-ifications that reduce risk exposure, others in the form of processimprovements that identify and eliminate or better manage risks.ese advances have allowed us to manage the increase of ourclients’ activity, while reducing HSE incidents at the same time.”

In June, Schlumberger introduced a step change in fracturingtechnology with the commercialization of its HiWAY flow-chan-nel hydraulic fracturing service, which delivers increased pro-duction with 45% less proppant. “Some of the challenges today infracturing revolve around the scale of the fracture operations andthe amount of equipment and volumes of proppant and fluidsrequired,” Lafferty added. “Significant advances will come throughtechnologies that deliver improved production results with lessequipment and materials.”

Weatherford International’s focus on safety was highlighted in itsfirst frac job completed in Egypt. “is area was well known for itstight formations – permeabilities on the order of three millidarcies –and a relatively high fracture gradient. ese conditions make failureof the fracturing operation a distinct possibility,” said Mostafa Amin

Amer, regional operations manager of reservoir stimulation and wellservices for Weatherford’s Middle East and North Africa business unit.

e company brought a new fleet of equipment and state-of-the-art fluid technology to the region. In an effort to ensure safe, stream-lined frac operations, other Weatherford equipment wasincorporated into the project as well, including well-completiontechnology, engineered chemistry, and wellhead-control valves.

“Our commitment to safe operations is what prompted us toinstall a safety restraint system on the wellhead,” Amer said. “In theevent of any overpressure of the pumping line or wellhead, therestraint system limits movement of the equipment, making theoperation safer for workers in the field.” According to Amer, thissafety requirement is so important to the company that the use of arestraint system is mandated in the company’s safety policies.

IInnnnoovvaattiioonnss iinn ffrraaccttuurriinngg,, ssttiimmuullaattiioonnHydraulic fracturing and stimulation treatments to restore orenhance well productivity are performed in all types of formationsand reservoir environments and are critical components of well eco-nomics. Production can be maximized not only by creating highlyconductive reservoir flow paths, but by selecting the appropriatetreatment for each environment. According to Schlumberger, itsmatrix stimulation and hydraulic fracturing techniques aredesigned to repair and improve the natural connection of the wellbore with the reservoir. “Matrix acidization treatments are used tomitigate the effects of formation damage, the biggest hindrance toproductivity in highly permeable reservoirs,” according to the com-pany. “Better reservoir knowledge and increasingly sensitive tech-nologies are making production of unconventional gaseconomically viable and more efficient. is efficiency is bringingtight gas, coalbed methane, and gas hydrates into the reach of morecompanies around the world.”

One innovative technique being used by many frac companies is“simul-fracs,” or “zipper fracs,” in which two or more parallel wellsare drilled and then perforated at alternate intervals along the wellbores and fractured at the perforations. is creates a high-densitynetwork of fractures between the wells that increases production inboth wells. By holding frac pressure on one well while the adjacentwell is being fraced, the fractures tend to avoid each other becauseof the stress pattern set up in the pressured-up well. In the zippertechnique, the alternating stages are fraced in sequence, resultingin a maximum of new reservoir rock exposed.

As the industry increases its technological might, challengesthat seemed insurmountable just a few years ago are being mas-tered and put into practice. And although gas shales have capturedthe most attention for the last several years, the relative price of oiland condensates is driving interest in oil shales and a differentfracturing paradigm.

“e challenge in getting better results,” Lafferty said, “lies in theprocess of identifying and integrating the combination of tech-nologies that will deliver improved performance for the specific welland reservoir conditions.” �

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