Workshop Covers Scope of Deepwater Completions

One hundred forty attendees participated in the SPE Deepwater Completions Applied Technology Workshop (ATW) held in Galveston, Texas, and organized by Steering Committee Chairperson Syed Ali of Chevron. Kevin Lacy of BP presented the keynote speech, “Deepwater Completions—Failure Is Not an Option!” Seven informal technical sessions were conducted during the 2-day workshop. Topics included

Drilling/Completion Interface, chaired by Earl Coludrovich of Chevron and Lee Nirider of Marathon Oil.
Upper-Completion Design, chaired by Stu Gosch of BP and Travis Hailey of Halliburton.
Sandface Completion, chaired by Hugo Morales of Schlumberger and Brian Stewart of Devon Energy.
Completion Evaluation, chaired by Mike Hecker of ExxonMobil and Tim Walker of Energy XXI U.S.A.
New Technology Gaps, chaired by Jackie LaFontaine of Shell and Mike Loudermilk of Baker Oil Tools.
Life-Cycle Management, chaired by Mitch Cornette of Chevron and Kevin Renfro of Anadarko.
Best Practices, chaired by Sam Larkin of ConocoPhillips and John Mather of Chevron.

Lacy kicked off the ATW, noting the industry’s fundamental mission to find new resources, convert resources to reserves, monetize reserves at a “fair” profit, and reinvest profits to find new resources. Companies and managers that can effectively recognize, develop, and reward “mission-critical” skills not only survive but thrive, he said. Completions engineering is mission critical—for example, a successful single-well subsea tieback can provide a net present value of U.S. $136 million, but if the completion fails after 3 years, the net present value can drop by $65 million. He noted that completion costs had risen from 10–20% of total well-construction costs in the 1970s to today, where they are 40–50% and, in the near future, will be more than 50%. In the 1970s, drilling was considered a separate operation from completions, but today, drilling and completions usually are integrated into one “well construction” department. However, those departments usually are managed by people with drilling backgrounds; therefore, the complexities of completions—especially in deep water—and their “mission criticality” are often neither well understood nor appreciated, he said. He challenged the completions-engineering community to work toward driving cultural changes in drilling and completions to attain leadership and commitment at all levels of the organization and to attain data-based communication, effective supplier partnerships, and common processes.

Drilling/Completion Interface

Jack Burman of Exploitation Technologies discussed 10 wells developed for Anadarko and pointed out a number of rig-logistics opportunities that were exploited to save rig time. These included an annular “slick joint” of SM 2550 material to reduce blowout preventer wear between overhauls and improve control while doing multiple frac packs; the use of long (approximately 93 ft) assemblies lifted into place with a riser skate to reduce “invisible lost time” during completion operations and use of equally long intelligent-well packer assemblies; and working from this riser skate to use greater than 30-ft assemblies in wellbore cleanouts, tubing-conveyed perforating, pulling packer plugs and wear bushings, and in placing gravel-pack assemblies.

Fluid Compatibility Testing

Bill Foxenberg of M-I Swaco reviewed extensive prejob fluid-compatibility testing that reduces costs by fixing problems during the planning stages, testing for compatibility of possible completion fluids with formation fluids, crude oil, formation waters, formation rock (with return-permeability studies), gravel-pack/frac-pack fluids, control-line fluids, and well materials of construction. He stressed the engineering of displacement spacers to reduce the size of transition zones and to improve the cleanup of all downhole equipment before any further completion steps.

Annular-Pressure Management

Rich Miller of Viking Engineering introduced annular-pressure management as an interface issue: The drilling department owns the casing design; the completions department delivers the producing well; the reservoir department predicts rates, fluids, and temperatures; and yet other disciplines get involved at this interface. Therefore, the development of a robust design requires multidisciplinary interaction. He categorized industry approaches in three ways:

To build mitigation into the drilling program with the most design flexibility in response to the most uncertainty.
To delay mitigation decisions until the completion phase.
To hope, pray, or wait for retirement.

An approach Miller recommended involved designing for a lightweight packer fluid to reduce the likelihood of a tubing leak, and install nitrified spacers, rupture disks, and syntactic foam to mitigate potential annular-pressure buildup.

Upper-Completion Design

Laurence Cowie of BP America gave an overview of BP’s Gulf of Mexico deepwater production hydrate-management options for high-water-cut wells. For cold restarts, antiagglomerant low-dosage hydrate inhibitors are used for hydrate management. He reviewed advantages and limitations, process, and downstream-impact consid-erations as well as testing for hydrate-inhibitor qualification.

Future Intelligent Completions

Joddie Carlile of WellDynamics discussed remotely operated adaptive completion systems beginning to be deployed in deepwater and high-pressure/high-temperature (HP/HT) completions, eight of which Devon installed recently in 4,700 ft of water depth. These wells required technological developments and involved high-pressure, complex completion hardware to deal with reservoir compaction; wellbore integrity after producing to low reservoir pressure; thick-walled casing resulting in associated perforating debris; fine-grained formations requiring premium screens; thick completion sections, high-rate producers; ultralong zones to perforate and frac pack; and flow-assurance issues.

Seal Considerations

Buc Slay of Halliburton introduced the NORSOK M-710 list of required elastomer properties—specific gravity and hardness, tensile properties, compression set, low-temperature properties, tear properties, the Gehman low-temperature plot, aging properties, and rapid gas decompression. He foresees future developments that will include production-company involvement in deepwater and HP/HT environments that will drive the development of new seal systems and the creation of qualification requirements. At the same time, the production companies will drive compliance. Seal-system qualification methods will need to simulate service conditions, and specifications will become more performance-based.

Sandface Completion

Mike Mullen of Mullen Energy listed the key lessons learned from operations that successfully frac packed long perforated intervals in a single stage, achieving low-to-negative skin values. Beyond the low skin values, key observations were that sand-control integrity can be maintained in long intervals after extreme reservoir depletion and that sand volume placed in long-interval frac packs is not related directly to flow rate or sand-control reliability.

Proppants and Fluids

Dave Norman of Chevron noted that sandface-completion issues in deep water begin with testing the fluids, where concerns include temperature at the seafloor, fluid-shear history, fluid density, changes in fluid formulation in response to formation issues, compatibility, and return permeability. Order of testing was addressed. The temperature inversion at the mudline takes on more importance in deep water because it can inhibit the full development of fluid properties, especially if there is a flow interruption and part of the fluid cools down significantly. Issues identified included flow mechanics being more complicated and more critical with large work strings and the hard surfaces on the tool joints generating iron filings during trips in and out of the hole, leading to greater problems with dissolved iron in completion fluids.

Perforating

Larry Berhmann of Schlumberger described today’s sand-control completion—conventional, phased, big-hole charges with large area-open-to-flow; overbalanced perforating; single-trip post-perforating surge into a closed chamber; reverse circulation of hydrocarbons and sand-to-surface holding tank; kill well with pill, run gravel-pack completion, acidize kill pill; and gravel pack. He predicted that tomorrow’s producers would be perforated overbalanced in an optimized noninvasive, sealing perforating fluid.

Completion Evaluation

Richard Keck of BP discussed the application of flux-based sand-control guidelines at the Na Kika deepwater fields, where new field-planning and off-take guidelines were used to set safe maximum rates after two pressure buildups, and, later in the life of the well, to monitor increased skin. The impact from this work is to bring the field up to targeted production rates without compromising long-term sand-control reliability, to identify incremental rate opportunities to extend the production plateau, and to lower the number of workovers during field life.

Optimizing Well Rates

Andy Brickell of BHP Billiton described using production logging and petrophysical analysis to optimize well rates. He presented production-logging-tool (PLT) results and contrasted the flux predictions before and after running the PLT. Brickell concluded with additional observations from the PLT.

Frac-Pack-Completion Diagnostics

Buddy Woodroof of Core Lab discussed frac pack-completion diagnostics. He noted that use of radioactive tracing and spectral gamma ray/density logging discloses new areas where reservoir completion response is not well understood and allows comparing and assessing various completion designs and methodologies. It also facilitates fieldwide stimulation-program surveillance, troubleshooting anomalous stimulation results, engineering field studies to optimize well spacing, determining bypassed or missed reserves, positively determining the mechanical integrity of the completion, and directly measuring enhanced-oil-recovery efficiency and performance.

New Technology Gaps

Matt Marek ofAnadarko presented lessons learned completing an ultradeep well, noting that little things can become big things when working at 29,000 ft. Large work strings and annular volumes require special operational and analytical considerations when frac packing, and debris management is a constant battle.

Functional Requirements for Qualifying Expandable Completions

Arnis Judzis of TerraTek/Schlumberger discussed how functional requirements are helping to qualify new expandable completions and how recent studies and products are influencing the choices. The strategic objectives for expandable screens are to deliver reliable, high-productivity sand-control completions, demonstrating high well performance and assuring effective sand control; to provide best-in-class installation efficiency for sand-control completions; to deliver fast installation with a low-risk sand-control operation; to deliver sand-control completions with enhanced functionality; and to provide the capability for selective completion and zonal isolation.

He concluded that

Functional requirements for expandable completions allow operators to compare completions methods.
The development of a broad set of technical specifications allows performance metrics to be set for a variety of fields, wells, well types, and downhole conditions.
Assurance programs to reduce risks identified by the failure-mode studies have commenced.
Functional requirements can be used by a “scorecard” approach to help qualify new products.

Testing an Invert Mud for Gravel Packing Horizontal Wells

Mark Luyster of M-I Swaco presented a discussion of planning for openhole gravel-pack horizontal completions using a reversible invert reservoir-drill-in system. The typical completion design is a dual completion with a lower open-hole gravel pack and an upper frac pack with a perforated liner with prepacked wire-wrapped screens. The fluid system for drilling the reservoir section was a reversible invert fluid at 9.7–10.0 lbm/gal; and for completion, a chelant-based breaker system in 11 to 22% KCl.

Nonaqueous Fluid in Horizontal-Gravel-Pack Displacement

L.F. Neumann of Petrobras described the placement of the alpha- and beta-waves in a horizontal-gravel-pack displacement using a nonaqueous fluid. The advantages of this approach include eliminating the possibility of an immobile water bed in the horizontal section; enabling drilling and completion in reservoirs that are sensitive to water-based fluids; and guaranteeing the possibility to drill the buildup section (normally composed of shale) and a reservoir in a single phase while maintaining the 8½-in.-diameter in the reservoir with the 5½-in.-diameter screen, leading to higher productivity. Furthermore, this approach guarantees the possibility of using the regular premium screen rather than screens with extra paths, and it enables the use of OHGP, which is a sand-controlling system that is more reliable, allows ample testing, and has been proved to be quite positive in a great variety of scenarios encountered in the Campos basin.

Life-Cycle Management

Mike Simmons of Noble Energy recounted a number of lessons learned at the Swordfish deepwater development to diagnose and treat the source of unexpected water production:

Go the “extra mile” to inspect equipment of third-party vendors and subcontractors.
Engage the operating crew on the Dp Msv in planning ahead.
Perform a system-integration test onshore involving the intervention riser system before deploying it.
Find out what operations will precede yours
Consider how they might impact third-party vendors on board.
Electrical-submersible-pump (ESP) penetrator for deep open-water applications needs more development.
Actively manage the hand-over from one operator to another.
Off-load and load-out can be time-consuming.
Select location.
Watch for disconnects between in-town support and vessel operating teams.

Subsea/Deepwater ESP Completions

Peter Lawson of Centrilift reviewed current technology for deepwater artificial lift, assessed current barriers to progress, and projected future developments. He noted the world’s first deployment of dual ESP systems in a subsea well at Total’s Otter deepwater development, including a 14.2-mile electrical stepout (longest to date), a subsea electrical switch, a dual-penetration ESP packer, and a dual-ESP system with interventionless changeover. Lawson also provided brief case studies of other emerging technologies—a single-pump caisson system, an ESP jumper that uses existing infrastructure and existing ESP components for greenfield or brownfield applications, and multiwell boosting.

Geomechanics of Water Injection

Ahmed Abou-Sayed of Advantek Intl. discussed the geomechanics of water injection and made the following recommendations: Shorter well lengths are preferable for injectivity; increasing choke ensures larger rates/pressures; operate at 100% choke; cycling and periodic shutoff maintain higher injectivity; increased rates/pressure lead to fracturing; deploying excess pumping capability allows for upsets or prolonged increase in the solid/oil loading; and reducing the injection temperature is advisable.

Best Practices

Scott Bennett of Devon discussed the Magnolia deepwater development, where design and operational best practices were developed in the process of dealing with issues connected with the successful installation of eight control lines. He recommended that operators hold tension on lines by releasing the drum brake and increasing the air pressure on the backspooling motor, closely monitor couplings while passing through slips to ensure that lines do not crimp, use plastic-wrapped control lines to prevent shifting, and be vigilant when unspooling to rigup. On workovers, Bennett recommended that operators leave spools rigged up from previous completions, splice lines at the rig floor, pull lines over the sheave to the spooler, swap spools out on “blue” flatpacks at mudline packoff tubing hanger, avoid reusing the lines, and add “poor boy” level wind to the spooler.

Current Status of Completion Benchmarking

Jonathan Parry of Chevron Energy Technology reviewed the current status of petroleum industry completion benchmarking. He noted that current methodologies to benchmark completions performance are focused on standard execution metrics—cost, time, and safety—but seldom address completion productivity. Parry challenged the workshop to consider where the added value of completion-productivity benchmarking lies and discover an optimum balance between cost and productivity. He concluded that despite significant efforts made to include completions performance in early project phases, most of the current benchmarking in the industry is driven by cost-schedule measures. Parry recommended completion representation at future Upstream Industry Benchmarking Conferences; proposed an industry standard on completions benchmarking and performance measurements through technical networks, conferences, consortia, and forums; encouraged the establishment of a global data-base that will enable operating companies to compare their completions performance against industry benchmarks; and examined the suitability of well-completions metrics, allowing tracking involvement of completions design vs. final completion performance.