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| Horizontal Drilling |
Horizontal drilling
is an applied science of Petroleum Engineering is a knowledge of drilling
techniques in the warp direction of the wellbore from vertical depth horizontal
direction at a certain distance and direction to achieve a target formation.
When viewed simply drilling a well as if very easy to penetrate a layer
formation that contains oil and gas, but the horizontal drilling is done with
sophisticated equipment and complex. Success in using all the equipment
obtained through studies and the development of technology experience. With horizontal
wells, causing more and more people are interested in doing the drilling of
horizontal wells for horizontal wells provides better productivity compared to
vertical wells.
Horizontal
drilling is generally done based on several considerations, among others, is to
reduce the occurrence of water coning with the best interval of a certain layer
of oil. Horizontal drilling is often performed on a thin layer of oil (thin
reservoir), low permeability, many have a vertical fracture. Also on oil
formations that are below a city, under the restricted areas or protected. This
drilling technique can also be carried out to produce formations under the sea
not far from the beach.
With
the horizontal drilling can optimize oil recovery, so that the area draining
the productive zone can be expanded. The tilt angle or inclination of
horizontal drilling can reach 90 ° to the vertical position and heading into
productive formations horizontally following the deployment of the reservoir
rock field that aims to:
•
Increase the production rate and recovery rate.
•
Reduce the number of development wells.
The
main objective of horizontal drilling is done to optimize well productivity by
extending the drainage area of the well.
When the current drilling horizontally can
diklafikasikan in four (Figure 2) categories using the build rate that is
different from the angle inclinasi can reach 90 ° to the vertical, ie drilling
horizontally by using ultra short radius, short radius, medium radius and long
radius (conventional ).
Long
Radius
Long
radius is the standard system used in the oil field for directional drilling
technology. Long radius or conventional horizontal wells have biuld-rate 2 ° to
6 ° / 100 feet (30 m) and build 1000ft-3000ft radius. The length of the
horizontal section can reach 1000ft-5000ft.
Long
radius drilling a three part (phase) from the top of the wellhead to the bottom
.Fase 1 is a vertical drilling to KOP (Kick of Point). Phase 2 drilling is
directed from KOP to the target point, and Phase 3 is drilling that has a
horizontal direction. Determination of the total depth of each phase
disensuaikan with slope formation.
Medium
Radius
Mechanical
drilling medium radius horizontal wells have been developed by modifying of
conventional drilling and produce a build rate between 6o to 60 ° / 100ft
(30m). Mechanical medium radius has a radius of curvature of between 125-700
feet, with long horizontal section reaches 3000 feet (915 m), and the same
diameter as the wells of long radius.
Short Radius
On
the lateral drilling Short Radius produce a level of build formation rate
between 1.5 to 3 ° / feet. Mechanical medium radius having a radius of
curvature between 20ft- 40ft, with the length of the horizontal section is
smaller daari reach 800ft
Short
radius lateral drilling would require very special equipment to support this
horizontal drilling systems.
Ultrashort - Radius
The
fourth category, sometimes - sometimes separately for ultrashort methods -
Radius, using the action of the jetting nozzle of the high pressure at the end
of the nozzle at the end of a flexible pipe directions. Possibility angle build
rate can reach 90 ° / feet.
For
what directional drilling is done?
Conventionally
drilled wells in a straight approaching the vertical direction. Directional
drilling (directional drilling) is drilling wells where the wellbore is not
straight vertical, but rather targeted to achieve the desired targets.
The
goal can be manifold:
- sidetracking: if there is an obstruction in front of the wellbore to be drilled, the wellbore inevitable or warped to avoid obstacles.
- If desired reservoir located just below an area that is not possible drilling, such as the city, residential areas, nature reserves or somewhere a highly sensitive environment. The well can be dug from elsewhere and are directed towards the reservoir is concerned.
- To avoid salt-dome (salt formations which continuously keep moving) which can damage the wellbore. Often hydrocarbons found under or around salt-dome. Directional drilling can be done to reach the reservoir and avoid salt-dome.
- To avoid faults (geological fault).
- To create a branch multiple wells from one lubung wells on the surface.
- To access the reservoir located under the ocean but rignya located on land so it can be cheaper.
- Generally in offshore, some wells may be drilled from the same platform making it easier, faster and cheaper.
- For the relief well to wells that are not controlled (blow-out).
- To create horizontal wells with the aim of raising the production of hydrocarbons.
- Extended Reach: horizontal wells that have parts that are longer than 5000m.
- Multilateral wells: one wellbore at the surface but has several branches laterally at the bottom, to be able to access several separate hydrocarbon formations.
Directional
drilling can be done with conventional drill equipment, where the drill pipe is
rotated from the surface to rotate the drill bit at the bottom. The
disadvantage, the angle can be formed very limited. Directional drilling is now
more commonly done using a motor having a mud (mud motor) which will rotate the
drill bit and drilling pipe installed at the end. The entire drilling pipe from
the surface does not need to be screened, more drilling pipe can be
"curved" so the pit can be more flexible to be directed.
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more: www.petrorad.com
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