BP has successfully performed the industry's first completion from a dynamically positioned (DP) vessel. The success of the completion, on BP's Nile project in the Gulf of Mexico using the DP Transocean Enterprise, was critical not just because it was a first, but because BP has a large corporate investment in the deepwater Gulf.

Teamwork ensures successful completion for Nile Project

BP has successfully performed the industry's first completion from a dynamically positioned (DP) vessel. The success of the completion, on BP's Nile project in the Gulf of Mexico using the DP Transocean Enterprise, was critical not just because it was a first, but because BP has a large corporate investment in the deepwater Gulf.

In addition to the challenges posed by completing seven wells in water depths ranging from 3,500 to 6,400 ft, Schlumberger Well Services took on the task of developing, proving, and supplying a subsea completion. The system had associated high-speed, multifunction control systems with Commander telemetry, IRIS dual-valve surge chambers, customized perforating, and environmentally friendly well cleanup facilities.

BP has frequently stated that it would not attempt a deepwater completion from a DP vessel without adequate safety systems in place. This requirement was satisfied, along with a number of technology firsts:

  • First subsea tree with a Commander control system
  • Special, big-hole, deep-penetrating charges
  • Transient rapid underbalanced surge technique
  • Formation isolation valve tool in a gravel-pack assembly
  • First early production facility in the Gulf of Mexico.

This deployment makes BP a formidable competitor in the deepwater completion market in the Gulf.

A crucial element in the project's success was the long-range planning, dating back to 1997, that went into the design and coordination. This lead-time allowed full cooperation and interaction among the companies and all product lines. The technological edge gained by the success of this project has led to the completion of additional wells in up to 6,400 ft water depth (the current world record completion for a horizontal tree).

The development of the most critical component involved in this project, the Sen7 subsea test tree with the Commander hydraulic controls system, was handled through the designated business center. It is this system that will allow operators to perform all tasks required when completing deepwater wells from a DP vessel. This system will allow operators to develop fields in water depths that would previously been beyond the capabilities of equipment and systems.

Another key factor in successfully developing the project was the decision to use proven technology instead of designing new or unique components. This decision had two major impacts on the project. One was to reduce the manufacturing and design time, which directly impacted the cost. But probably the more important result was increased reliability. Using proven technology dramatically reduced the probability of a component failure and added to the sense of reliability for a tool that had yet to be run.

Engineers designed the perforating-surge string to dynamically underbalance the perforations and surge the formation without producing hydrocarbons to surface. The system used a novel combination of existing commercially available hardware and allowed the perforating and surging to be performed in two independent steps on the same pipe trip into the well.

Ultra-deepwater record: 9,727 ft

Unocal Corporation's Trident prospect in Alaminos Canyon, Block 903, in the Gulf of Mexico set a new ultra-deepwater record in 9,727 ft water depth. The success of the cementing, drilling fluid, directional drilling, logging-while-drilling (LWD), surface data logging (SDL), and real-time operations (RTO) services help set the latest record besting the previous record of 9,687 ft water depth. The well encountered more than 300 net ft of hydrocarbon pay, identified at approximately 20,500 ft total depth.

These ultra-deepwater milestones further illustrate the value of teamwork in achieving a trouble-free, complete real-time reservoir solution. The entire business development and Gulf of Mexico operation teams reduced drilling days in a safe environment and on budget.

In setting the latest water depth record, Unocal relied on Halliburton Energy Services' Cementing, Baroid Drilling Fluids, and Sperry-Sun product service lines. HES Cementing provided the operator with the ZoneSeal foamed cement process, which integrates the SPU-180, automated nitrogen unit with the Advantage cementing skid. The process has the ability accommodate on-the-fly changes in the slurry design. This is critical, as it can prevent downtime due to delays associated with the transportation of additional additives for unplanned slurry design modifications.

The total-fluids-management team worked in conjunction with Unocal to develop the formulation for the synthetic-based drilling fluid. The team also provided ongoing fluids engineering for the project, allowing these wells to be drilled with fewer days on location, while maintaining superior hole integrity.

For the directional drilling, LWD, SDL, and RTO services at the well the team used specially designed equipment that can help alleviate issues typically encountered in deepwater and ultra-deepwater drilling environments. These issues include flow rate and operating pressure limitations. The equipment includes an 8-in., high-flow Bi-modal AcousTic LWD sonic tool. It also includes an 8-in., high-flow compensated thermal neutron logging sensor with an integrated caliper sensor that can withstand higher downhole hydrostatic pressures.

Methodology designed to optimize drilling

An Aberdeen-based engineering company Innovative Engineering Systems Ltd's (IESL) well construction system, GeoDRILL, is to be used by Canadian Natural Resources CNR subsidiary, Ranger Oil Côte d'Ivoire SARL, on wells in two fields off the Ivory Coast, West Africa.

This system, a methodology designed to optimize the drilling process through analysis and statistical field validated models to prevent wellbore fracture and collapse, is being used in the Espoir oil and gas field and in a nearby deepwater prospect.

In the Espoir field, the system will be used on seven wells with depleted reservoir pressure and a water depth of up to 1,400 ft. The wells also have a shale/sandstone-layered reservoir that could prove problematic to drill.

The deepwater prospect off the Ivory Coast will see the system being used to a water depth of 4,900 ft on a directional well through a shale section. The system can be used as a design or evaluation tool for the drilling of new or existing wells - it provides information on optimum mud weights required for drilling through problematic shales, unconsolidated sections or severely depleted reservoirs. Also, it can determine optimum drilling fluid flow rates required to ensure maximum hole cleaning which helps to avoid problems such as stuck pipe, high drag and torque, or even complete loss of the well.

This system has three main modules; drill cutting size determination, computational fluid dynamics, and geomechanical modeling. It can be used in the planning stages, during early operation when problems arise, and can conduct daily monitoring as well as give advance warning of instability or hole cleaning problems.

Perforation flow laboratory

A new Perforation Flow Laboratory has been developed that can simulate a wide range of well conditions and flow measurement options to accommodate low permeability hard rock and high permeability unconsolidated sand samples. Designed to address the deficiencies in validation data, the laboratory provides detailed instrumentation and controlled-laboratory conditions that can allow insight into physical phenomena occurring in the reservoir during complicated perforating and multi-phase flow events. This is a new element addition to the Halliburton PerfPro process.

The PerfPro process improves the design and optimization of perforating systems and to optimize well inflow performance using a standardized process and analysis tools. A three-pronged approach, using laboratory tests, theoretical models, and field tests, provides a process that can quantitatively determine the optimal perforating system design for a given reservoir formation.

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