SCHLUMBERGER PIONEERS RECORD DEEPWATER OPEN-HOLE GRAVEL PACK COMPLETIONS

Two extremes define Perdido’s early development wells: The water is very deep, and the reservoirs are very shallow below the mudline. The difficulty for drillers is the small difference between the amount of pressure required to control the wellbore and the amount of pressure required to fracture the rock around it.

In the Silvertip field, where Schlumberger completed Perdido’s first two development wells, the narrow pressure window is so low that conventional open-hole gravel pack treatments would be at risk.

“The challenge is to pump the gravel slurry at a low enough pressure to keep it from fracturing and entering the formation, without reducing the effectiveness of the gravel placement,” says Salah Al-Harthy, Schlumberger well completion engineer. “The efficiency of the gravel pack directly affects the productive life of an open hole well. Any voids will expose the screens to erosion and possible well failure.”

Perdido’s first two development wells were drilled from a floating rig in the Silvertip field, in 9,400 feet of water. The targeted zone was the Oligocene-Frio sands, a portion of the Lower Tertiary that consists of as many as six separate reservoirs from 1,500 to 2,500 feet below the mudline.

Horizontal open hole completion with OptiPac

The wells reached a maximum total depth of 16,513 feet, with horizontal open-hole length of 2,300 feet. Since the Oligocene-Frio sands may compact as they are produced, well planners decided to complete these sands with a horizontal open-hole gravel pack to enhance the longevity of these completions in a highly compressive reservoir.

“There were two primary challenges in completing these sands with horizontal open-hole gravel packs,” Al-Harthy says. “The first challenge was the narrow pressure window and the second challenge was the selection of carrier fluid.”

 

Designing the completions

 

The fracture gradient of the targeted Oligocene-Frio sands was about 7,100 psi. With reservoir pressures of 6,700 psi, that meant the pressure window for placing the gravel pack was only 400 psi. The risk of such a narrow operating window is that the reservoir rock can fracture during treatment, causing premature screen-out and insufficient packing around the screens.

OptiPac screens and cutaway section of a nozzle

The requirement for the gravel packing carrier fluid needed to have enough carrying capacity to suspend the gravel and remove the filter cake after the gravel was placed. It also needed to have a low corrosion rate around the sand control screens, since the wells were being completed more than a year before first oil.

To overcome these challenges, Schlumberger used two of its flagship technologies, the OptiPac* Alternate Path† systems, and its ClearPAC* MS gravel packing fluid system, to ensure a complete pack around the sand control screens.

OptiPac Alternate Path systems use shunt-tube technology to fill the voids that can form during gravel packing even under fracturing conditions. The shunts are installed along the screens, each with a series of evenly placed nozzles.

Schlumberger DeepSTIM II stimulation vessel

“When a bridge forms, the slurry naturally diverts into the shunts,” Al-Harthy says. “When slurry encounters a nozzle facing a void in the open hole, it flows out to fill the unpacked annulus, and the process continues until the interval is fully packed.”

OptiPac systems are part of an integrated approach that ensures that screens are fully protected in high flow-rate wells, and is utilized in-conjunction with SandCADE*, gravel-pack design and evaluation software to help engineers design, execute and evaluate the entire job.

ClearPAC MS, which is an advanced viscoelastic surfactant, was selected as the carrier fluid on the first two Silvertip wells because of its excellent sand suspension capabilities, even at very low shear rates. The sand suspension and low friction pressure characteristics allow it to perform exceptionally well in the long intervals of both open hole and cased hole completions. The ClearPAC MS fluid also incorporates a breaker system (based on MudSOLV technology) to help dissolve filter cake that remains in the wellbore after the gravel pack is completed. By combining the breaker system with the carrier fluid this allowed Shell to eliminate the need to reenter the well, saving valuable rig time.

ClearPAC MS Fluids are used in OptiPac operations to ensure proper gravel transportation and controlled leakoff through the nozzles of packing shunts.

“To compensate for the narrow operating pressure, we also modified the mixing equipment on our stimulation vessel,” Al-Harthy says.

This equipment, called the POD* programmable optimum density blender, mixes the fluid and the gravel before it enters the pump. The POD normally operates at rates of above six barrels a minute, but for the Perdido wells the equipment was modified to accept half the rate of fluid and proppant, to maintain pumping pressures within the narrow margins.

“We conducted a number of trials and extensive modeling beforehand to make sure that the equipment, fluid and overall design would perform as planned,” says Al-Harthy.

 

Monitoring in real time

 

Throughout the process, Shell and Schlumberger engineers in distant locations were able to collaborate efficiently in real time using the InterACT* connectivity, collaboration, and information system. InterACT’s robust design allows it to continue working, even in areas with marginal communication links.

MudSOLV: Filter Cake Breaker
Part A shows nonaggressive, slow-acting, MudSOLV solutions remove the filtercake more uniformly, resulting in higher retained permeability across the entire interval.

Part B shows aggressive treatments like acid create localized open areas (wormholes or pinholes) in the filtercake, leaving large areas of filtercake unremoved, generally over areas having lower permeability.

 

Working the plan

 

“We really did our homework,” Al-Harthy adds. “Using powerful models and simulations, we worked together in a highly collaborative environment with Shell, to evaluate all the risks and to ensure successful execution. Perdido is a frontier development, so there were many uncertainties, but at the end of the day the modeling was correct and these jobs were performed as designed. The work we did on those first two wells will guide many of Perdido’s future well completions.”

*Mark of Schlumberger

†Mark of ExxonMobil Corp.; technology licensed exclusively to Schlumberger

Schlumberger
1325 S. Dairy Ashford
Houston, TX 77077
U.S.A.
Tel: +1 281 285 1300
Website: www.slb.com/sandcontrol

Related Articles

Fabricating the Single-Lift Topsides

07/01/2010 The Perdido team faced a tough decision. A conventional topsides design required a series of modules that would have to be fabricated onshore, then...

Technology and Teamwork Achieve World Class Success for Shell Perdido

04/01/2010 In the high-risk ultra deepwater environment, success depends on two key components: technology and teamwork. Shell and Technip have applied innova...

The Bayou Companies provide welding, coating and insulation services around the world

04/01/2010 Straight on the heels of successfully fabricating and supplying pipe line end terminals (PLET) for Shell’s Ursa/Princess waterflood project, ...

Oceaneering Installs Record Diverless Deepwater HOOPS Tie-in

04/01/2010 Who would cut a perfectly good pipeline? Oceaneering worked with Shell to add a new tie-in for the Perdido oil export pipeline to the currently ope...

Kiewit Offshore Services experience and no surprises approach results in quality services for the offshore oil and gas industry

04/01/2010 KOS’ extensive experience in fabricating large, complex topsides enabled the company to meet the challenges associated with the multi-discipl...

Noble Corp.’s innovative engineering helps Shell to develop Perdido

04/01/2010 Long before the industry dared to dream that operating in the ultra-deepwater of the U.S. Gulf of Mexico could be possible, Noble took a bold and p...

H&Ps Rig 205 ready for Perdido Spar drilling, completions, interventions

04/01/2010

With special modifications, 20,000-ft SCR rig to tackle subsea wells located in up to 9,627 feet of water

HORNBECK OFFSHORE SHELTERED SOME OF PERDIDO’S MOST VALUABLE ASSETS

04/01/2010 As many as 220 people per shift came to work aboard the Perdido deepwater spar during the peak of commissioning and hookup, but it was a short comm...

Halliburton Providing Life-of-Field Solutions for Shell Perdido

04/01/2010 The Shell Perdido project represents an industry milestone in overcoming the technology challenges of ultra-deep waters, subsalt drilling, and comp...

White Papers

AVEVA NET Accesses and Manages the Digital Asset

Global demand for new process plants, power plants and infrastructure is increasing steadily with the ...
Sponsored by

AVEVA’s Approach for the Digital Asset

To meet the requirements for leaner project execution and more efficient operations while transferring...
Sponsored by

Diversification - the technology aspects

In tough times, businesses seek to diversify into adjacent markets or to apply their skills and resour...
Sponsored by

Engineering & Design for Lean Construction

Modern marketing rhetoric claims that, in order to cut out expensive costs and reduce risks during the...
Sponsored by

Object Lessons - Why control of engineering design at the object level is essential for efficient project execution

Whatever the task, there is usually only one way to do it right and many more to do it wrong. In the c...
Sponsored by

Plant Design for Lean Construction - at your fingertips

One area which can provide improvements to the adoption of Lean principles is the application of mobil...
Sponsored by

How to Keep Your Mud System Vibrator Hose from Getting Hammered to Death

To prevent the vibrating hoses on your oilfield mud circulation systems from failing, you must examine...
Sponsored by

Duty of Care

Good corporate social responsibility means implementing effective workplace health and safety measures...
Sponsored by

Available Webcasts


On Demand

Optimizing your asset management practices to mitigate the effects of a down market

Thu, Dec 11, 2014

The oil and gas market is in constant flux, and as the price of BOE (Barrel of Oil Equivalent) goes down it is increasingly important to optimize your asset management strategy to stay afloat.  Attend this webinar to learn how developing a solid asset management plan can help your company mitigate costs in any market.

register:WEBCAST


Parylene Conformal Coatings for the Oil & Gas Industry

Thu, Nov 20, 2014

In this concise 30-minute webinar, participants have an opportunity to learn more about how Parylene coatings are applied, their features, and the value they add to devices and components.

register:WEBCAST


Utilizing Predictive Analytics to Optimize Productivity in Oil & Gas Operations

Tue, Nov 18, 2014

Join IBM on Tuesday, November 18 @ 1pm CST to explore how Predictive Analytics can help your organization maximize productivity, operational performance & associated processes to drive enterprise wide productivity and profitability.

register:WEBCAST


US HYDROCARBON EXPORTS Part 3 — LNG

Fri, Nov 14, 2014

US LNG Exports, the third in a trilogy of webcasts focusing on the broad topic of US Hydrocarbon Exports.

A discussion of the problems and potential for the export of US-produced liquefied natural gas.

These and other topics will be discussed, with the latest thoughts on U.S. LNG export policy.

register:WEBCAST


Careers at TOTAL

Careers at TOTAL - Videos

More than 600 job openings are now online, watch videos and learn more!

 

Click Here to Watch

Other Oil & Gas Industry Jobs

Search More Job Listings >>
Stay Connected