E P M A G . C O M

J U N E 2 0 1 1

UnconventionalResource

Development

Advances in Mooring Systems

Testing andProduction

Management

Frontier Exploration

LWD/MWD

Special Report: BRAZIL

UnconventionalResource

Development

Advances in Mooring Systems

Testing andProduction

Management

Frontier Exploration

LWD/MWD

Special Report: BRAZIL

UnconventionalResource

Development

Advances in Mooring Systems

Testing andProduction

Management

Frontier Exploration

LWD/MWD

Special Report: BRAZIL

Well construction techniques remain static to somedegree. When necessary, engineers look for ways

to enhance and improve current technology to providelower cost and less risk in a variety of drilling applications.From spud to stimulation, several companies are look-

ing at the full drilling cycle to develop tools that can pro-vide a seamless approach to the well construction process.

Engineering RSS performanceFor any horizontal well, the payzone begins after thecurve is built. Achieving a successful, efficient high doglegseverity (DLS) can exponentially improve the perform-ance and payout of an individual well. Limitations to highbuild rates include increased friction, bending of tools,and added stress on costly bottomhole assembly (BHA).When being rotated through these high build rate sec-

tions, BHAs experience large bending moments. Fatiguelife reduces exponentially with increasing build-rate. This can reduce the life of standard BHA components to a matter of hours. Without a method of modeling and tracking fatigue, catastrophic failure and twist-off of BHA components could occur.The Schlumberger PowerDrive Archer high build-rate

rotary steerable system (RSS) provides the means to drillwell profiles with high dogleg severity in order to maxi-mize reservoir exposure and increase the potential forhydrocarbon recovery and combine this with the tradi-tional RSS benefits of increased effective drilling effi-ciency and superior wellbore quality.

Field trials began in 2008, and the functionality and reli-ability of the service proved to be very robust. Due to thissystem’s unique capability in terms of dogleg provision asecond stage of field testing was necessary. This supple-mentary stage was to design and ensure that any BHAused did not impact the build rate capabilities of the PowerDrive Archer system and that any extra fatigue generated through rotating a drill string through a high dogleg wellbore could be managed.“For the first time we are bringing fully rotating BHAs

to high build rate well profiles,” said Richard Hawkins,product champion, Schlumberger. The PowerDrive Archer is a fully rotating system. “As

with the entire PowerDrive RSS family, anything exposedto the wellbore rotates at drillstring rpm as a minimum,”Hawkins said. This rotation reduces drag, improves ROP,decreases the risk of differential mechanical sticking, andachieves superior borehole cleaning and conditioning.This reduced friction is especially important when drillinghorizontal sections, as the total length that can be drilledis potentially extended. Running casing is also significantlyless problematic due to a smoother and cleaner wellbore.Borehole quality is fundamental for drilling optimiza-

tion. This includes maximizing borehole cleaning andminimizing tortuosity and wash-outs. With openhole com-pletions, a smooth borehole leads to less chance of bore-hole problems and key seating.For cased hole completions, a smooth wellbore with a

constant DLS leads to much easier deployment of comple-

June 2011 | EPmag.com

Tayvis Dunnahoe Senior Editor

EPmag.com | June 2011

COVER STORY:DOWNHOLE SYSTEMS & TOOLS

tion equipment than with the typically tortuous slide-rotate profile delivered with motors. “In the Eagle Ford,we have seen up to a 20% reduction in wellbore tortuos-ity,” Hawkins said.The company has performed comprehensive finite ele-

ment analysis and detailed strain-based fatigue studies onall the components in the PowerDrive Archer BHA tounderstand the effects onthem when subjected tohigh doglegs. “We areusing fatigue-resistantmaterials and have a pre-dicted fatigue life for allthe BHA components,”Hawkins said. Trackingthis fatigue life isextremely complex. The company’s PerformToolkit data optimizationand analysis software is provided to automati-cally track tool fatigueand substantially reducethe risk of failure.The full rotation is a

key feature of the serviceand is achieved throughan advanced control sys-tem, which allows theelectronic assembly insidethe tool to be held geosta-tionary while everythingexposed to the wellborerotates. “Effectively, we measure the exact rotating speed(rpm) of the external drill collar and then use a controlsystem to hold an internal valve at a constant toolface,”Hawkins said. “We then divert a small percentage of themud flow through the valve to activate the system at therequired toolface.” In field trials, PowerDrive Archer delivered up to 17

deg/100 ft (17 deg/30.5 m), both from vertical or manyother inclinations. “We accurately measure magnetic toolface, so the wellbore trajectory can be kicked off on thedesired azimuth even from vertical,” Hawkins said. Thetool can drill out the shoe, come off a whipstock orcement plug, stay perfectly vertical, ream or back ream,

and then kick off accurately with high build rates. Thetool can then continue to drill whatever well profile isneeded and do this all in a single run. “PowerDrive Archeris a drilling system, one that incorporates bit and BHAdesign,” Hawkins said.

Hybrid tool provides steerabilityThe bottom line for high-end RSS systems is high cost.The application of RSS in the field has proven its advan-tage in terms of reducing drilling times and gaining accessto the reservoir; however, reluctance to drill with RSSreigns for wells having a high risk of lost-in-hole outcomes.

For conventional directional drilling the use of a mudmotor and sliding often provides the means by whichoperators can control the trajectory of any well. Whilethese tools are reliable and proven through a long historyof field use, they come with limitations for complex welltrajectories. Nevertheless, additional drilling time is prefer-able to lost time resulting from a stuck RSS tool.Weatherford International has developed its Motary-

Steerable tool as a bridge between mud motors, rotarysteerables, and MWD. The hybrid system outperforms amotor-only approach while providing less risk than anadvanced RSS system. “At the low end of the tool box are conventional mud motor tools and directional control

EPmag.com | June 2011

Baker Hughes’ FracPoint EX-C provides

the ability to fracture up to 40 stages in series with

continuous pumping operations using 1⁄16-in. increments in ball and seat sizes. (Image courtesy of Baker Hughes)

The PowerDrive Archer RSS delivers well profiles previously only possible with motors—yet with the ROP

and wellbore quality of a fully rotating RSS. (Image courtesy of Schlumberger)

June 2011 | EPmag.com

systems, and the high end includes traditional rotary steerable tools like Revolution,” said Chris Maranuk, new product launch manager, Weatherford International.“MotarySteerable is a tool that essentially combines MWD and mud motor technology to create a low-angleassist tool.”According to Maranuk, the combination of MWD,

drilling motors, and RSS experience within a single groupof engineers was critical to conceiving this product. “Thebiggest challenge to making MotarySteerable work was toovercome the barriers between each of the drilling prod-ucts and remove individual objectives in favor of a greatergoal,” Maranuk said.In traditional oriented drilling, a bent sub is used to

point the bit and then turned by the drilling motor to

drill the hole directionally. During rotary drilling, twosources of rotation are available, but directional control is lost; the bend orientation becomes irrelevant due tothe rotation of the drill string, and the rotational energy is used to drill the hole. Weatherford’s Motary-Steerable tool uses targeted bit speed (TBS) to reversethis approach by directly controlling the drilling motorspeed to target orientation. The bend is turned continu-ously with the drill string while motor speed is varied as afunction of bend orientation to change the rate of pene-tration as a function of bend position. “This is the sameapproach as oriented drilling—point the motor and drillahead—with the exception that it is done once per revo-lution of the drill string,” Maranuk said.A key feature of MotarySteerable system is the ability

to change from TBS to sliding without trip-ping out of the hole. “The ability to use TBSto change directional control has always beena key requirement for this particular system,”Maranuk said. As the system has undergonetesting, Weatherford has developed selectiveupdates to enhance the tool’s functionality. “One of the more interesting capabilities is

the auto inc feature that allows the user todownload a desired inclination and let the sys-tem self-correct downhole,” Maranuk said.The tool automatically turns on when theinclination starts to wander out of its presetlimits and turns off when not required. Thetool can be turned off or on through a varietyof methods including downlinking throughtraditional surface-initiated pressure pulses orby using various rotational sequences. “Ofcourse, the key benefit of providing the capac-ity to change from a sliding oriented string toa full 3-D directional rotating string from the surface is the flexibility in terms of operatordrilling practices,” Maranuk said.The MotarySteerable system takes advan-

tage of two proven technologies, mud motorsand MWD, to create a very reliable robust system. In drilling environments where the system is unable to obtain the desired buildrates, one can always stop, orient, and thenslide using conventional directional drillingtechniques, so it offers a very low-risk technol-ogy. One can expect lower lost–in-hole coststhan traditional rotary steerable tools. The key advantage over traditional oriented direc-tional drilling techniques is its ability to offerfull 3-D directional control while continuouslyrotating.

COVER STORY:DOWNHOLE SYSTEMS & TOOLS

The MotarySteerable System takes advantage of two centerlines of a mud motor to

target bit speed to provide full 3-D rotating (directional) control. (Image courtesy

of Weatherford International)

“Not every operator who drills a well in the US needs ahigh dog leg rotary steerable tool with a full quad comboLWD to drill and evaluate their well,” Maranuk said. “Wesee a need for this type of service to help complimentthose customers who might need a more economicalsolution with less system performance but yet full 3-Dcontinuous rotation directional control.”

Longer laterals, more frac stagesAs drilling operations come to a close, completionsoperations take effect. Fracing technology has under-gone a multitude of advances in recent years, and companies continually engineer this process to providefurther performance not only in execution but also in outcomes.Baker Hughes Inc. recently completed a record-

setting 40-stage frac job in North America’s WillistonBasin, which is known for extremely long laterals –some in excess of 9,000 ft. (2,743 m). The Baker Hughes FracPoint multistage open hole

fracturing system is currently used to complete an aver-age of 19 stages per well in the US, which is up from five stages in 2006. “With the introduction of this latestgeneration system, we expect this average number toapproach 30 by year end,” said Matthew Kebodeaux,vice president Completions, Baker Hughes. The com-pany’s latest achievement was delivered with its Frac-Point EX-C system. Operators performing plug and perf operations to achieve their desired number ofstages can now switch over to openhole multistage fracturing, which is more cost-effective because of therig time savings.“Even though every shale formation is different, there

is a growing consensus in the industry that more stagesequal more production, so our clients are continuallyrequesting increasing numbers of stages per well toshorten the frac spacing interval, improve fracture effi-ciency, and increase their production on a per wellbasis,” Kebodeaux said. Baker Hughes’ latest version of the FracPoint EX-C

provides the ability to fracture up to 40 stages in serieswith continuous pumping operations using 1⁄16-in. incre-ments in ball and seat sizes. In addition, the FracPoint EX-C system does more than just increase the number of available stages; it also allows the use of larger ballseats on wells that do not require a full 40-stage system,which allows for increased pump rates during the fracand reduced pressure losses during production. The FracPoint EX-C system uses a combination of

patented features, which include double barrel seats andcollapsible ball seats. The double barrel seat has two par-allel bores that permit a substantial increase in flow rate

over a single ball seat when deploying smaller size balls. The collapsible ball seat allows the contact area of the seat to change once the ball lands, which in turn increases the load carrying capacity of the seat and allows the system to meet the pressures ratingsrequired. “Baker Hughes has been deploying 24-stageFracPoint EX-C systems since September 2009, so theconcept and functional performance of the tool isproven,” Kebodeaux said.The results of the first completions performed with

the 40-stage FracPoint EX-C system have been very favor-able. The company is embarking on its next improve-ment of this system with the release of its IN-tallic FracBalls, using controlled electrolytic materials technology,which is an engineered material that provides highstrength while disintegrating in a controlled manner in the presence of brines and acids.The company expects to deploy FracPoint EX-C tech-

nology in every basin where high-quantity openholemultistage completions are used. As the industry trendstoward longer laterals, providing more frac stages in lesstime has become the goal of service companies likeBaker Hughes. “While these initial 40-stage FracPointjobs have saved our clients an estimated 5 days per com-pletion over a 40 stage plug and perf job, the key todelivering real value for our clients is in increasing lat-eral lengths and improving fracture efficiency, therebyreducing the spacing between wells,” Kebodeaux said.

Beyond status quo“When Packers Plus began doing openhole fracturing in2001, the industry believed that 5-8 fracture treatmentscould effectively drain a 4,000 ft (1,000 m) horizontalwell,” said Dan Themig, President and CEO, PackersPlus. The company’s StackFRAC HD is an innovativeapproach that challenged the status quo on what isrequired to effectively drain tight gas and oil resourceplays. The industry has quickly applied this technologyto move to 20 fracture treatments per well, but the HDsystems from Packers Plus – including its newlylaunched QuickFRAC system – are now moving to 30-60fracs, a number – unfathomed four years ago. “Webelieve this is the future of development for shale gasand oil,” Themig said.This technology also applies to conventional plays,

where historically the approach has been “downspacing”in drilling patterns from 640 acres to (eventually) 10acres. StackFRAC HD allows 10-acre drainage patternswith fewer wells at surface, greatly improving economics,but also greatly reducing water usage and environmentalconcerns.Unlike conventional cemented casing completions,

June 2011 | EPmag.com

COVER STORY:DOWNHOLE SYSTEMS & TOOLS

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COVER STORY:DOWNHOLE SYSTEMS & TOOLS

which plug natural fractures and attempt to restore con-nection to the formation with fracturing, the StackFRACHD system is designed to allow stimulation of openholehorizontal wells. This allows the rock to produce fromboth natural and induced fractures. “Production compar-isons on the two methods show that openhole comple-tions (StackFRAC) outperform cemented completionsfrom 25 to 70%, not just in initial productivity, but alsosimilarly improving ultimate recovery,” Themig said.In cemented completions, the fracture is forced to ini-

tiate at perforations, rather than allowing them to initi-ate in natural weakness of the rock. StackFRAC HDallows the fractures to both initiate at a weakness in therock rather than at perforations. Thus, it allows the frac-ture to initiate and propagate at the same point, greatlyreducing tortuosity. In addition, StackFRAC HD allowsfor accurate displacement of proppant without overdis-placing. “We are seeing a massive shift and acceptancethat openhole fracturing produces much better ultimaterecovery of resources and in many cases can allow thereduction of water usage by as much as 50% per stage,”Themig added.StackFRAC HD also greatly reduces the time required

to stimulate a well. Instead of utilizing wireline pump-down bridge plugs and coiled tubing, resulting in exces-sive time to perform fracturing, StackFRAC HD allows aball to be launched and pumped downhole on the fly,seamlessly moving from stage to stage. QuickFRAC hasallowed for even more time savings by fracturing multipleisolated stages with a single fracture treatment from sur-face. “Our record using QuickFRAC technology has seen23 stages pumped in less than 10 hours,” Themig said.“Conventional methods treating 2-3 stages per day, wouldhave taken 7-10 days.”

Looking aheadAt the end of the day, there are countless opportunitiesto cover the many advances that occur in downholetechnology. The systems discussed here represent a frac-tion of the output from a multitude of engineeringteams. By observing both older and newer ways ofimproving drilling efficiencies, the industry will con-tinue to hone current technologies to improve on veryspecific parts of the process and to provide the widestrange of applications throughout the world’s oil and gas producing regions.

Packers Plus QuickFRAC multi-stage batch fracturing system enables simultaneous stimulation of multiple stages (group) with a single

fracture treatment at surface. (Image courtesy of Packers Plus)