Value Moment

ELECTRICAL HAZARD

HALLIBURTON

ELECTRICAL HAZARD

HALLIBURTON

DEEP WATER DRILLINGDEEP WATER DRILLING

December, 2008

Presented by: Tamer Gamal Bashandy

Deep water drilling

• Deepwater exploration and production have significant potential in many offshore locations around the world.

• Deepwater drilling, in general, has a greater degree of difficulty than conventional drilling and presents many operational challenges.

To classify well as deepwater, the water depth should be greater than 1500 ft.

RIG TYPE WATER DEPTH

COMPLIANT TOWER 1500 ft to 3000 ft

SEA STAR 500 ft to 3500 ft

FLOATING PRODUCTION 1500 ft to 6000 ft

TENSION LEG PLATFORM 1500 ft to 7000 ft

SEMISUBMERSIBLE 3000 ft to 8000 ft

DRILLSHIP UP to 10,000 ft

SPAR PLATFORM 2000 to 10,000

Rigs used in deep water drilling

Examples of deepwater drilling rigs

• A list of fluid design issues and considerations includes:

– Gas hydrates.

– Geology/reactive formations.

– Pore pressure and low fracture gradients.

– Riser volumes/large-casing well designs/logistics.

– Low flow line temperatures.

– High daily rig costs.

Deep water drilling challenges

Gas hydrates are a solid mixture of natural gas and water which looks like dirty ice.

At high pressures, gas hydrates will form at moderate temperatures higher than 32ºF.

Gas hydrates occur naturally in deepwater seabed deposits.

Gas Hydrates

Why gas hydrates are dangerous?

A- The severity of gas hydrates come from that small amount of hydrates give larger amount of natural gas than its original volume.

1 ft3 of hydrates can gives 170 ft3 of natural gas

B- When hydrates start to form they can cause blockages in the BOP.

SOLUTIONS

The following precautions can stop hydrates forming:

1- Primary well control = No gas in wellbore.

2- Temperature (increase) = Circulate hot fluid.

3-Composition of mud = Additives (Salts, Glycol).

Salinity Vs Temperature at which hydrates form

NaCl (wt%) Temperature at which hydrates may form ºF

O% 0

5% -4

10% -9

15% -15

20% -23

25% -31

Geology/Reactive formations• The geology of deepwater drilling is different from that on land and in

shallow water.

The formations are relatively young and very reactive.

The clays and silts have not been altered by extreme heat or pressure.

Sands are often unconsolidated and have not been compacted.

Shallow clay formations, referred to as gumbo, are very soft and sticky.

Geology/Reactive formations

SOLUTIONS

• High performance Water-base systems will required to minimize trouble with soft, sticky gumbo .

BARASILC ™ HYDRO-GUARD ™ BOREMAX ™ KCL/PHPA/GEM GP POLYMER ™

• Synthetic and oil-base systems provide excellent inhibition: INVERMUL ™ ENVIROMUL ™ PETROFREE ™ XP-07 ™

Low Fracture Gradients

• In deepwater drilling pore pressures and fracture gradients being very close.

• For deepwater applications, the fracture gradient decrease as water depth increases due to the lack of overburden .

• Surge, swab and ECD pressures are a significant concern for all deepwater drilling operations.

SOLUTIONS

Use frequent shallow casing strings to seal off low fracture-gradient formations.

Use lowest mud weight as practical as possible.

Use blend of STEEL SEAL & BARACARB.

Run Baroid DFG™ program to calculate surge pressure and optimum tripping speeds, specially in slim holes and while running casing.

Large Mud Volumes Wells drilled in deep water require long risers and

large diameter casing strings.

A 20-in. ID riser in 2,500 ft of water has a volume of 972 bbl.

It is common for a deepwater drilling operation to have a circulating system of 4,000 bbl or more.

These large systems require larger quantities of mud additives

for maintenance and treating.

SOLUTIONS

• Logistics

–Inventory management is critical

–Delivery time

–Sea conditions

•Considerations

–Bulk bags (1 ton or more)

–Floating liquid storage for brines

–Bulk handling systems

–Proper estimates

Low Flow Line Temperatures• As explained earlier, water temperature decreases with depth.

• Long risers surrounded by cold sea water will result in much colder mud temperatures.

• Shale shaker screens limitations.

• Avoid treating the mud system to reduce the viscosity at the flow line, since it will reduce hole cleaning in the riser.

SOLUTIONS

Circulating a third “boost” mud pump on the riser .

A Fann70 viscometer can be used to provide a more accurate profile of the effects of cold and hot temperatures and pressures on mud.

High Rig Costs The practices of drilling and completing wells in deep water are high-cost

operations.

Optimization can be achieved through proper planning to reduce cost and maximize productivity.

A low-cost approach to fluids is not always the correct approach for deepwater projects.

The cost of a high-performance mud system can be offset easily by the savings in rig cost realized by reducing the number of days required to complete the project.

REFRENCES

• Canadian Petroleum Institute.

• Transocean drilling.

• Geology of egypt.

• Internet websites.

• Thanks

•Questions