2009 ep versatile hwo

8/9/2019 2009 EP Versatile HWO

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A Hart Energy Publication May 2009www.EPmag.com

GLOBAL EXPLORATION & PRODUCTIO N NEWS • TECHNOLO GY UPDATES • ANALYSI

Workovers/WelInterventions

Versatile HWO/snubbing

units offer multiple benefitsover conventional rigs



Steadily advancing HWO and snubbing technologies have merged to provide a viable and economic alternative to conventional rigs in a host of onshore and offshore drilling, completion, and live-well intervention applications.

AUTHORS

Steve Wehrenberg and Mike Ponville ,

Boots & Coots

W hile hydraulic workover(HWO)/snubbing will never

wholly replace traditional workover rigs, particularly in dead wellapplications requiring multiple trips andfishing jobs, in live and pressured wellre-entries the technology offers myriadoperational; economic; and health,safety, and environment advantages.From its inception solely as a mechanismfor handing tubulars during well control

operations, hydraulic snubbing technol-ogy has evolved into a mechanism that can perform any operation once consid-ered the sole jurisdiction of conventionaldrilling and workover rigs.

The ability of modularHWO/snubbing units to pull existingcompletions, drill open holes, and re-complete a well bore at flowing (near-bal-anced or underbalanced) conditions haseffectively bridged the technological gapbetween derrick equipment configura-tions and coiled tubing (CT) units.

Consequently, standalone or rig-assistedHWO/snubbing units have beenemployed successfully in a variety of activ-ities worldwide, from re-completions andcompletions under pressure to tubing-conveyed perforating to the drilling of sidetracks, slim holes, and well deepen-ing operations, among others.

Faster rigup, rigdownTogether with its capacity to rotate pipein live well conditions and perform inter-

vention operations without having to

shut in production entirely,

HWO/snubbing units can often bemobilized and de-mobilized in a fractionof the time and associated costs of a con-

ventional workover rig.Key to the comparably faster and more

cost-effective mobilization and de-mobi-lization is the modular design that allowsHWO/snubbing units with up to 600,000lb hook load and rotary torque in excess

of 14,000 ft/lb to be transported easily by air, sea, or over land. Accordingly, themodular design, in tandem with a com-paratively minimal footprint as small as2,500 sq ft (753 sq m), makes the tech-nology an ideal contender for applica-tions on remote offshore platforms.

Depending on the wellhead equip-ment, one of the foremost drivers for thegrowing use of HWO/snubbing units is adesign engineered specifically to operateunder pressures as high as 20,000 psi.Consequently, operators can perform a

variety of well intervention operations

without having to first kill the well anddiscontinue production completely.

Cost efficienciesCompounding the costs associated withlost production is the expense of killingthe well and re-initiating productiononce the re-entry operation is completed.By way of illustration, installing a comple-

tion string after a typical fracturing jobrequires that the operator first employ high-density fluid to kill the well. In addi-tion to the costs of the brine and killpump are the rig-related expenses associ-ated with running the pipe in the wellbore. Afterwards, a CT unit and nitrogenmay have to be used to re-start produc-tion, magnifying the costs even further.

By comparison, an HWO/snubbingunit normally can perform the sameoperation in one to two days with pro-duction continuing while the operation

is under way. All things considered and

Versatile HWO/snubbing units offermultiple benefits over conventional rigs

An HWO/snubbing unit in operation onshore Louisiana. (Images courtesy of Boots & Coots)

E&P | May 2009 www.EPmag.com

Workovers/Well Interventions



Workovers/Well Interventions

depending on the specific application,

employing an HWO/snubbing unit gen-erally is more cost-effective on new andproducing wells than a conventional

workover rig and is less than that of thedaily rate for a CT unit.

Besides the production revenue lost during the balanced well intervention,there also is the risk of future shortfallsresulting from reservoir damage causedby the introduction of overbalanced killfluids that are especially harmful to someshales and other highly reactive forma-tions. Hydraulic snubbing not only can

use existing pipe and tubing for workstring, but it does not rely on kill-weight fluids to bring the well bore to static con-dition. Consequently, the risk of reser-

voir damage is minimized dramatically or eliminated altogether.

Moreover, with HWO/snubbing tech-nology, the operator avoids the costs andpotential environmental liabilities associ-ated with the onshore/offshore disposalof heavy-weight kill fluid. Also from anenvironmental perspective, since lessequipment is required on location, oper-

ators do not have to flow the well toatmosphere to maintain pressure con-trol, thus further reducing the carbonfootprint. Since the units do not requireany water from nearby streams or under-ground aquifers, hydraulic snubbing isespecially beneficial in areas where wateris a premium or scarce resource.

Snubbing evolutionContemporary hydraulic snubbing tech-nology bears little resemblance to theunits introduced in 1929, only 10 years

after the development of well cementing.Those first units comprised little morethan a series of cables, sheaves, andcounterweights and were used strictly for

well control operations and snubbing inlive completions.

At their conception, snubbing unitsrelied on a rig’s drawworks to hoist pipein and out of the hole, and the sheaves

were rigged up so that as the travelingblocks hoisted upward, the pipe wouldbe snubbed into the well. Conversely,lowering the traveling blocks brought

the pipe out of the hole.

Over the years, increased understand-ing of hydraulics resulted in the develop-ment of the “concentric” snubbing unit,

which consisted of a hollow hydrauliccylinder. This design also created the first pipe guide that prevented the bucklingthat plagued earlier units and allowedoperators to work on higher-pressure

wells with longer strokes, which reducedthe time required to complete the job.

Soon afterwards, the first multicylindersnubbing unit was developed, which wasa prototype of the system used today.The industry also developed specializedslips and blowout preventers (BOPs)configured for the purpose of snub-bing/stripping. As the unit designs pro-gressed, they incorporated stronger ginpoles and hydraulic rotary tables. Today,a standard HWO unit can be trans-formed into an HWO/snubbing unit inan hour with the simple addition of twosets of slips and a tubing guide.

The steady progression of hydraulicsnubbing coincided with drillingadvancements that have led to the wide-spread construction of ultraextended-reach drilling, multilaterals, and otherunconventional wells that all too oftenare outside the capability of conventionalservice tools and technologies. In uncon-

ventional plays and well configurations,the advantages of HWO/snubbing tomore conventional CT units, for exam-ple, are evident. Unlike CT, the ability torotate the pipe and work string dramati-

cally reduces wall-to-wall frictional drag.

In turn, minimizing friction increases

depth capability significantly, crucial inlaterals that extend past 3,000 ft (915 m).

HWO at workThe benefits of hydraulic snubbing inunconventional applications recently

were illustrated in the tight gas North Jonah field in Wyoming’s Pinedale Anticline. Since production from thefield was uneconomical using conven-tional technologies, hydraulic snubbing

was employed, allowing the well to bedrilled and completed simultaneously.

Hydraulic snubbing in concert with aninnovative flowback package allowed the

well to begin production even as the livecompletion was still under way.

Elsewhere, in an oil producer offshoreDubai, the technology was used in a livere-completion encompassing tubing-con-

veyed perforating (TCP) guns and acidstimulation at a well depth of 9,500 ft (2,898 m). After pulling the completion,the operator was able to run a cast-ironbridge plug and TCP guns before perfo-rating. After successfully performing the

acid stimulation, the hydraulic snubbingunit was used to run the re-completionassembly. From rigup to rigdown, theoperation required 15 twelve-hour days.

The technology also was applied in adry and pressurized re-completion ofan onshore 16,000-ft (4,880-m) deepgas well in Sharjah. After the tree wasfrozen and removed, the BOP stack wasinstalled and the 5-in. production stringpulled from the hole. Afterwards, atapered 27 ⁄ 8-in. to 31 ⁄ 2-in. productionstring was run in the hole to 8,500 ft

(2,593 m), at which time a retrievablebridge plug was used to isolate thereservoir from surface to change out the hanger spool. The remaining com-pletion installation was completed with31 ⁄ 2-in. production tubing. The entireoperation, including rigup and rig-down, was completed in 11 days.

The versatility of HWO/snubbing tech-nology allows operators to do more withless as illustrated by the platform in the

Gulf of Mexico where operations are per- formed via guy wire beams.



Considering the size of most E&P investments, it’s natural to be concerned about the

well-being of your operation. No one is more experienced than Boots & Coots at providingpressure control services. Our snubbing/hydraulic workover services and pressure control

rental tools set the industry standard. You’ll rest much easier with Boots & Coots on your

team. So call 1.281.931.8884 or 1.800.BLOWOUT today. And relax.

2009 ep versatile hwo

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