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Challenging Subsea Gas Lift Application, Offshore Norway
by: Paulsen, Magnus — Added 6/28/2009 12:00:00 AMGeneral - Offshore Gas-Lift

Offshore, subsea applications provide a challenging environment for gas-lift equipment. Reliability is paramount as well intervention costs lead to little or no possibility of gas-lift valve change outs.

As the industry moves to deepwater and subsea production, costs increase significantly. Front end designs must consider artificial lift depletion plans to minimize life cycle costs. Higher lift gas supply rates and pressures, combined with more stringent regulatory agency requirements and the risks associated with floating structures, elevate the importance of well-bore integrity. Gas-lift practices and hardware that have been acceptable for onshore and continental shelf operations become less financially appealing due to the high cost and risk of well-bore entries to service in-well gas lift hardware.

One such application is StatoilHydro’s Norne Satellites development with five production wells tied back to a floating production storage and offloading vessel (FPSO). Gas-

Deepwater Gas-Lift: Issues and Considerations when Gas Lifting in a Deepwater Environment
by: Ghobrial, Nora — Added 6/24/2008 12:00:00 AMGeneral - Offshore Gas-Lift

Shell recently started up its first deepwater gas lift project at Ram/Powell and found that
gas-lifting in a deepwater environment poses a unique set of challenges. This presentation highlights the differences between Deepwater and Shelf environments including the safety issues involved and several project design and execution considerations when pursuing deepwater gas lift. Well design, facility design, and operational readiness items to consider are included.

Gas-Lift in TLP Wells
by: Robinson, Jerry — Added 6/24/2008 12:00:00 AMGeneral - Offshore Gas-Lift

Deepwater TLP completions in the Gulf of Mexico present several challenges for traditional gas lift methods. One of the first challenges is the mere fact that these types of wells are often located in water depths that can be as much as 6,500’. This deepwater environment dictates that special consideration be given, but not limited to: (1) Method of unloading the riser section, (2) Gas lift injection pressure for kickoff and operating, (3) Gas lift injection rate requirements, (4) Gas lift mandrel running OD’s, (5) Location of subsurface safety valve, (whether gas lift mandrels will be run above, below, or both, (6) Temperature profiles for accurately predicting static and flowing temperatures for setting nitrogen charged valves, and (7) accurate reservoir modeling to predict wells’ initial and future productivity.

Gas-Lifting a Subsea Tie-back at 65 Km
by: Wittfeld, Chad; Salman, Yaser; Wim der Kinderen — Added 3/31/2009 12:00:00 AMGeneral - Offshore Gas-Lift

The Penguins field is a cluster of reservoirs in the northern North Sea. The reservoir fluids range from black oil in the north at Penguin A to retrograde condensate in the south at Penguin E. The field is located at 50 to 65 km north of the Brent Charlie platform and is produced via a 16” commingled flowline. There are 4 drill centres and 9 wells in total. The reservoirs have no aquifer support; depletion drive is the primary recovery mechanism. The field has produced naturally from 2003. The need for gas-lift was foreseen in the Field Development Plan, to maximise ultimate recovery. The oil wells were therefore completed for gas-lift. These 5 wells have varying reservoir pressures, flow rates, and PVT properties.

Gas-Lifting on TLP’s
by: Ghobrial, Nora — Added 3/31/2009 12:00:00 AMGeneral - Offshore Gas-Lift

Shell is currently progressing several deepwater TLP gas-lift projects and has found that gas-lifting in a deepwater environment poses a unique set of challenges. This presentation highlights the differences between Deepwater and Shelf environments including the safety issues involved, the need for a holistic design approach, and several project design and execution considerations when pursuing deepwater TLP gas-lift. Well design, facility design, and operational readiness items to consider are included.

Optimizing Subsea Well Discharge Operations – Case Study Using Flowlift2
by: Lima, D. D. S.; Oliveira, G. P. H. A. — Added 6/29/2009 12:00:00 AMGeneral - Offshore Gas-Lift

This work presents a simplified model for dimensioning of sub sea well discharge operations through the wet Christmas trees, via the pig crossover valve. The model is supported by numerical simulation using PETROBRAS in-house software FlowLift2, and will be demonstrated through a case study.

FlowLift2 simulates transient black-oil two-phase flow and allows the monitoring of the evolution of relevant variables during the discharge operation time, such as pressures, velocities, and volumetric fractions throughout the production system.

This model allows the optimization of the discharge operation that promotes the anticipation of production wells start up. Furthermore, this study is relevant for ultra deep water production scenarios, where, in some cases, is not always possible to perform well discharge directly through the gas lift valves, due to pressure limitations of the compression system.

Oxy Computer Model Experience in Qatar
by: Mathews, Lee — Added 3/2/2009 12:00:00 AMGeneral - Offshore Gas-Lift

Occidental Petroleum of Qatar, Ltd. (OPQL) operates the Idd El Shargi field located offshore Qatar under a PSA from Qatar Petroleum (QP). Production is from 100 producing wellbores, located on 40 assorted tripod and nine-slot jackets. Gas lift is the primary lift mechanism with a few wells still naturally flowing. The production is delivered from the remote jackets to the PS-1 production station through a very complex and interactive gathering system of forty-four subsea pipelines. The pipelines vary in size from a single 6” line to 20” pipelines.

Petrobras Deep Water Gas Lift Project
by: Peixoto, Guilherme; RibeiJose Eduardoro, Paulo José Pinto; Resende de Almeida, Alcino; Mendonça da Silva, — Added 4/14/2008 12:00:00 AMGeneral - Offshore Gas-Lift

The Petrobras Deepwater Gas Lift Project is part of the PROCAP 3000 program and intends to face the challenges of gas lifting in high pressure and high flow rate deepwater wells. The main objective is to search for products that will optimize the gas lift process.

The work is focused in four areas of interest: study of scenarios, equipment development, software development, and gas lift automation. Phase 1 of the project is almost completed and Phase 2 will start soon.

The developed products, accomplished tests, and obtained results for Phase 1 of the project will be presented here, along with a summary.

Reliable Subsea Gas Lift System Meets the Challenge for Statoil’s NSD-URD Development
by: Stabell, Rina; White, Tommy; Lovie, Eric — Added 3/31/2009 12:00:00 AMGeneral - Offshore Gas-Lift

Statoil’s Norne Satellites Development (URD) lies about 125 mi. (200 km) from the north Norwegian coast at 66°N latitude, where the Norne FPSO produces from the Norne field and its two satellite fields, Staer and Svale. Staer is about 2.8 mi. (4.5 km) northeast of Norne, and Svale is an equal distance northeast of Staer. The satellites produce from three subsea installations comprising five producing oil wells and three water injection wells (Figure 1). Maximum reservoir depth is 8,150-ft (2,484 m), and water depth is about 1,245-ft (380 m). Significant uncertainties in identifying the properties and volumes of untested segments, led Statoil to believe that the best way to produce the Norne satellites was through the combination of open hole sand control completions with intelligent well systems augmented by high-performance gas lift and downhole injection of scale inhibitors.

Retrofit Gas-Lift on a Tension Leg Platform Well
by: Babajide, Abi — Added 6/28/2009 12:00:00 AMGeneral - Offshore Gas-Lift

When oil wells can no longer flow naturally, artificial lift methods are often employed. Most mechanical installations of artificial lift equipment require a complete workover of the well, involving pulling the well apart and re-running the completion with artificial lift. These methods can prove to be prohibitively expensive and/or risky, and so may not pass the economic hurdle to implement.

A tubing punch and pack-off gas-lift system, also known as an “econo-gas-lift” or retrofit gas-lift system may provide a less risky and economically viable means of bringing dead wells back on production or optimizing flowing wells. To the best of our knowledge, the use of retrofit gas-lift systems has been untested in a Tension Leg Platform (TLP) environment, and poses a new set of challenges as opposed to its use on offshore shelf locations.

A case study of the gas-lift retrofit of an oil well on a tension leg platform in the Gulf of Mexico demonstrates the usefulness of the proposed met

Rigless Gas Lift Conversion – A Success Story
by: Bikoro, Fortune — Added 6/25/2008 12:00:00 AMGeneral - Offshore Gas-Lift

MLC-1 is the only oil producer from the MLC satellite field located in block 405a onshore Algeria. It is part of the MLN field development operated by Burlington Resources. The MLN field oil production operations started mid-2003, and MLC-1 was open to production in December 2003.

The field has a defined maximum efficiency rate, or MER rate of 4,070 bopd, that it should not exceed. Within the first year, the oil production rate dropped from 4,200 bbls/d to 1,500 bbls/d due to reservoir depletion. There is no pressure support either by gas or water injection or any other producing well in the MLC field.

MLC-1 is a vertical well with 4.5” tubing to surface, stabbed into a 4.5” liner over the reservoir section. The well was completed with completion brine left in the annulus. The well is tied back to a facility which separates oil and gas from a number of fields and re-injects gas into other reservoirs at around 400bar. Therefore a high pressure gas source is available.

Subsea GL Undergoes Review
by: Ghobrial, Nora — Added 3/31/2009 12:00:00 AMGeneral - Offshore Gas-Lift

Subsea GL Undergoes Review will be about Shell's first proposed Gulf of Mexico sub-sea in-wellbore gas-lift project withstanding production engineering technical review. I will basically show the workshop how the project was technically defended and justified focusing on what portions of the production engineering/gas-lift segment of the project were challenged and how those challenges were answered. I hope to make this a peek into an instance when a real sub-sea gas-lift project underwent production engineering review.

The Use of Subsea Gas-Lift in Deepwater Applications
by: Jayawardena, Subash; Dykhno, Leonid; Zabaras, George — Added 3/31/2009 12:00:00 AMGeneral - Offshore Gas-Lift

Riser base gas-lift is a method that has been proven to work in subsea developments for production enhancement. In addition, gas-lift can be used to suppress severe slugging that usually occurs in flowlines with downhill inclination. In some cases, gas-lift can be used to assist in blow down for hydrate prevention.

Meanwhile, necessity of gas-lift application is not always obvious because gas-lift effectiveness depends on reservoir performance, fluid properties, seabed terrain, subsea architecture, and flowline and riser specifications. In many cases, gas-lift for production enhancement is only needed at late life production, when oil production rates are low and water rates relatively high. It is clear that the necessity of gas-lift, optimal operability and system design should be assessed from various aspects, including flow assurance.

TLP Gas-Lift Designs
by: Johnson, Milke; Hyde, Patrick — Added 6/24/2008 12:00:00 AMGeneral - Offshore Gas-Lift

ExxonMobil will present plans for the implementation of gas lift in new deepwater development.