PETROLEUM DEVELOPMENT GEOLOGY DRILLING

☯ Making a hole or well to make access into Pipeline to Flow Process and Storage Surface Casing Intermediate Casing Production Casing Completion Fluid Cement Packer Cement Cement Tubin

© Schlumberger 1999

☯ Making a hole or well to

make access into

Pipeline to Flow Process and Storage

Surface Casing

Intermediate Casing

Production Casing

Completion Fluid

Cement Packer

Cement

Cement

Tubing

Well Fluids

Oil or Gas Zone Perforations

OIL EXTRACTING HISTORY

In the earliest day of oil

production, oil was

collected from surface

seepages.

Mine shafts were dug to

make a well (like water

well in Java) to produce

shallow oil.

In the early 19th century

peoples developed cable

tool drilling

TYPE OF DRILLING :

• Cable Tool Drilling

• Rotary Rig Drilling

CABLE TOOL

DERRICK

JACK UP UNIT

A jack-up unit is a barge with legs that can be

lowered or raised The barge is towed to the

drilling location with its legs in the raised

position Once in position, the legs are lowered

When they reach the sea-bed, the barge's body

is hoisted above the water, creating a stable

drilling platform The length of the legs

determines the depth of water in which a

jack-up barge can be used They can generally be

used in up to 100 meters of water Jack-up

barges are widely employed in the relatively

shallow waters of the North Sea's Southern

basin

SEMI-SUBMERSIBLE RIG

A semi-submersible drilling rig is normally a propelled working platform supported by vertical columns on submerged pontoons By varying the amount of ballast water in the pontoons, the unit can be raised or lowered in the water

self-A semi-submersible vessel is normally held in position by up to eight very large anchors, or by dynamic positioning: computer controlled

directional propellers to keep the vessel stationary relative to the sea-bed, compensating for wind,

wave or current

Semi-submersibles can drill in water depths to 300 meters or more all year round

SETTING UP THE RIG

• Depending upon the remoteness of the

drill site and its access, equipment may be

transported to the site by truck,

helicopter or barge

• Some rigs are built on ships or barges for

work on inland water where there is no

foundation to support a rig (as in marshes

or lakes)

• Once the equipment is at the site, the rig

is set up Here are the major systems of

a land oil rig:

• Mechanical system - driven

by electric motors

– hoisting system - used for

lifting heavy loads; consists of

a mechanical winch

(drawworks) with a large

steel cable spool, a block-and- tackle pulley and a receiving storage reel for the cable

– turntable - part of the drilling

apparatus

• Power System

– large diesel engines - burn

diesel-fuel oil to provide the main source of power

– electrical generators -

powered by the diesel engines

to provide electrical power

• Derrick - support structure: holds

the drilling apparatus

sections of drill pipe to be

added to the drilling apparatus

as drilling progresses

• Blowout preventers and Rams -

high-pressure valves (located

below the rotary table or on the sea floor)

lines and relieve pressure

when necessary to prevent a blowout (uncontrolled gush of gas or oil to the surface, often associated with fire)

space (between pipe and well)

or the complete hole

• Rotating equipment - used for rotary

drilling

– swivel - large handle that holds the weight of

the drill string; allows the string to rotate and makes a pressure-tight seal on the hole

– kelly - four- or six-sided pipe that transfers

rotary motion to the turntable and drill string

– turntable or rotary table - drives the rotating

motion using power from electric motors

– drill string - consists of drill pipe

(connected sections of about 30 ft / 10 m)

and drill collars (larger diameter, heavier

pipe that fits around the drill pipe and places weight on the drill bit)

• Drill bit(s) - end of the drill that actually cuts

up the rock; comes in many shapes and

materials (tungsten carbide steel, diamond) that are specialized for various drilling tasks and rock formations

• Casing - large-diameter concrete pipe that

lines the drill hole, prevents the hole from collapsing, and allows drilling mud to

circulate

• There's more to drilling than simply rotating the bit.

• Fluid is circulated while the drilling proceeds.

• Powerful pumps move the fluid down the pipe, through the bit and back to the surface, carrying the cuttings and other debris with it.

• Thus, on a rotary rig (unlike the cable tool), drilling can be continuous as stopping to bail the cuttings is no

longer required.

• The drilling mud also stabilizes the walls of the hole

• Circulation system - pumps drilling mud under pressure through the kelly,

rotary table, drill pipes and drill collars

– pump - sucks mud from the mud pits

and pumps it to the drilling apparatus

– pipes and hoses - connects pump to

drilling apparatus

– mud-return line - returns mud from hole

– shale shaker - shaker/sieve that

separates rock cuttings from the mud

– shale slide - conveys cuttings to the

reserve pit

– reserve pit - collects rock cuttings

separated from the mud

– mud pits - where drilling mud is mixed

and recycled

– mud-mixing hopper - where new mud is

mixed and then sent to the mud pits

CONTROLLING

THE WEIGHT ON THE BIT

The weight is held partly by the hook etc If not, the drill bit wouldn’t turn! Collars are added to the drill string to add more weight

Hence the driller can control the weight on the bit by

adding/ removing collars or

by raising/lowering the

swivel tackle.

Which bit?

•Largest bit is used first, decreasing with depth

•For each formation & depth have a particular set of jet sizes, gallons per minte, pump strokes per minte, minimum annular velocity (speed mud returns at to keep the hole clean), bit hydraulic horsepower

•Hence the hydraulic and bit programs work in

tandem to most efficiently drill the well giving best

cost per foot, drilling time, minimum down time

• Drilling continues in stages:

– Drill

– run and cement new casings, then drill again

• When the rock cuttings from the mud reveal the oil sand from the reservoir rock, the final depth may have been reached

• At this point, the drilling apparatus is removed from the hole and perform several tests to confirm this finding:

– Well logging - lowering electrical and gas sensors into the hole

to take measurements of the rock formations

– Drill-stem testing - lowering a device into the hole to measure

the pressures, which will reveal whether reservoir rock has been reached

– Core samples - taking samples of rock to look for characteristics

of reservoir rock

PRODUCING

SAND

WELL COMPLETION TYPE

1 Openhole Openhole Completion

atas zona zona produktif produktif

(interest zone) Jadi Jadi sumur sumur

diproduksi

diproduksi dengan dengan kondisi kondisi

terbuka

terbuka di di sepanjang sepanjang zona zona

PACKER CEMENT

CASING

PRODUCTION STRING

2 Liner Completion

Ada dua model penyelesaian sumur

menggunakan Liner Completion :

1 Screen Liner Completion

Casing diset sampai di atas zona

produksi yang kemudian

digabungkan dengan kombinasi liner

dan screen yang tidak disemen di

seluruh permukaan zona produksi

2 Perforated Liner Completion

Metode penyelesaian sumur dengan

melakukan pemasangan liner dan

disemen pada zona produktif yang

kemudian dilaksanakan pelobangan

(perforated) pada zona-zona yang

paling produktif

CASING SHOE

PACKER CEMENT CASING

Perforated casing

completion adalah

penyelesaian sumur

dengan menutup semua

zona produktif dengan

PRODUCTION STRING

PERFORATION OIL SAND

THE MAST (CHRITMAST-TREE)

Setelah pemboran dinyatakan

berhasil dan mendapatkan minyak atau gas, maka di kepala sumur

dipasang chritmas tree yang

didefinisikan sebagai rangkaian

dari valve dan fitting yang

digunakan untuk control produksi dan disambungkan dengan bagian atas tubing head Pertama kali

christmas tree digunakan untuk

tekanan aliran rendah dan

menengah dari suatu sumur,

dimana rangkaian dari tees,

elbows, nipples, valve yang dibeli secara terpisah dan dirangkaikan jadi satu di lokasi

PRODUCING WELL

COMPLETION