2 descripción_proceso de perforacion_1

8/19/2019 2 Descripción_Proceso de Perforacion_1

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Exploring and Drillingfor Oil and Gas


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Where can we find Oil and Gas?


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Some people think that oil is in big pools underground.

Actually, most oil is trapped in the tiny pore spaces betweengrains of rock or sand. Most of these pores are too small to

be seen with the naked eye.


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How do we find oil-bearing rocks?

• Oil and gas are found in natural traps within the earth.

• These traps consist of domes or faults. Impermeable rock

above the trap prevents the oil and gas from migrating up

to surface. An “impermeable” rock is one that fluid

cannot pass through.

• Without traps, the oil and gas could migrate all the way to

the surface and evaporate.


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Oil

Example: A dome-shaped oil reservoir

Water


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Gas

Example: Oil reservoir with a gas cap

Oil

Water


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How do we find the oil reservoirs?

• Geophysicists find reservoirs by bouncing sound waves off

them, and timing how long it takes for the sound to come

back

• Computers process the data to construct pictures of what the

earth looks like underground.

Gas

Oil

source

receivers

t = 1 sec

t = 1.2 sect = 1.42 sec


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What do we do after we find areservoir?

?

??


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We Drill Into It ! ! !


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What do we drill with ?


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A Drilling Rig !

Here are a few different types of drilling rigs available:

Land Rig

For drilling on land.

Drill Ship

Drill ships and semi-submersible rigs are for drilling in

water depths from 100 to 5000+ ft.

Semi-Submersible Rig

Jackup Rig

For drilling in water

depths from 15 ft

to +/- 350 ft.

Inland Barge

For drilling in water depths

from 8 to 30 ft.


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What’s a drilling rig ?


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A Drilling Rig is:

A package of special equipment put together to enable us to

drill into the earth.

• A drilling rig has many different parts:

a derrick, a substructure, hoisting equipment, engines for

power, drill pipe, steel tanks, pumps, solids control

equipment, and many other pieces.


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Drill string

Drill bit

The hoisting equipmentconsists of:

a crown block,

a traveling block,

drilling line,

and a drawworks to

pull the drilling line up

or down.

substructure

derrick

This picture shows the hoisting equipment on a rig.This equipment is used to raise or lower the drillstring, which is

picked up in 30 foot long segments, or “joints”, of drill pipe.

spare drill pipe

This shows a 30 foot section

of drill pipe being added to

the drill pipe already in the

hole.


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Here’s a picture of the drill bit drilling the rock.

The drill string is turned at

surface, which turns the bit

at the bottom of the hole.

The teeth on the drill bit

grind the rock intofragments, or “cuttings”.

Drilling mud is

pumped down the inside

of the drill pipe, through

jet nozzles in the bit,

and into the “annulus”.

This is the space

between the sides of the

hole and the drill pipe.

The mud lifts the

cuttings and circulates

them back to surface

where they are removed.


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3) the mixture of drilling mud and

drill cuttings are circulated up the

annulus

screens

5) the drill cuttings are removed, and

form a cuttings pile. This can be

hauled off and disposed of.

4) the mixture is

circulated across

screens at surface

1) Clean drilling mud is taken from the steel

mud tanks and pumped down the inside of the

drill pipe.

2) the mud is circulated through the drill bit into the

annulus, lifting the cuttings removed by the drill bit.

6) Clean mud falls

through the screens

and is returned to the pits

The Drilling Mud Cycle

mud pump


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Here’s a sequence showing how holes are drilled

First, a large drill bit is used to drill

a short interval of hole.

Then, steel casing is run and cemented on

the outside to keep the hole from

collapsing.

0’

200’


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Next,a smaller bit is

run inside the

first casing.

This bit drills

out the bottom

of the casing,

and drills new

hole.

200’

0’

500’

Then, this newhole is also

cased off and

cemented.


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Again, a smallerhole is drilled out,

and smallercasing is run

to keep the

hole from

falling in.


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In this way, the hole is drilled in stages, until the target reservoir rock is penetrated. Atthis point, the geologists must figure out if there is oil or gas in it.


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They do this by running logs across the zone. Logs are tools run on electric cable(“wireline”) which record the physical properties in the rock such as resistivity, porosity,

density, radioactivity, and pore pressure.

How do Geologists tell if the reservoir has oil or gas?


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Sand

Shale

Siltstone

Shale

Siltstone

Dolomite

Shale

Here’s an example of what a log looks like. Geologists look at logs to decidewhether or not to complete a well (if there is oil), or abandon it (if there’s no oil).

Gamma

Radiation

200’

500’

3000’

Electrical

ResistivityPorosity

Looks

like

good

sand

quality

good

resistivity,

may have

oil or gas

poor

resistivity,

probably

water

good

porosity

poor porosity

good

porosity

poor

resistivity,

probably

water

poor

porosity

good

porosity


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Can you tell where the geologist would complete this well?Gamma

Radiation

200’

500’

3000’

Electrical

ResistivityPorosity

Lookslike

good

sand

quality

good

resistivity,

may have oil

or gas

poor

resistivity,

probably water

good porosity

poor

porosity

good porosity

poor

resistivity,

probably

water

poor porosity

good porosity

}Right here! This shows a clean sand,with good porosity and resistivity.

good porosity

poor porosity


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If the well looks good on the logs, we run a final stringof casing across the production zone, and cement it in place.


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Then, we run perforating guns in the hole and perforate (shootholes ) in the casing across the productive zone.


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Production tubing is run, with a packer to isolate the producedzone from the casing above.

tubing

Packer


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Finally, the well is produced intoa pipeline, which takes it to

production facilities on surface.


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The production facilities on surface separate out thegas, oil, and water into their separate phases.

Production Separator

Oil

Produced

Water

Produced Gas


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2 descripción_proceso de perforacion_1

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