This document discusses semisubmersible drilling rigs and logging while drilling (LWD). It begins by explaining how semisubmersibles work, noting they are partially submerged platforms that provide stability for drilling. It describes two main types of semisubmersibles and how dynamic positioning and mooring lines keep them in place for drilling. The document then discusses LWD, which involves tools that log wells in real-time while drilling, allowing drillers to make immediate decisions. LWD transmits data on properties like porosity and resistivity through mud pulses.

1. Oil and Gas
Industry

2. Source:
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• This training is designed to help everyone
who works in the Oil and Gas Industry
develop their speaking skills.

3. How Do Semisubmersibles Work?
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Source:
https://www.rigzone.com/training/insight.asp?insight_id=338&
c_id=24
3

4. Originally conceived as a bottom-supported drilling unit, semisubmersibles
eventually found their true calling. Now, semisubs are the most stable of any
floating rig, many times chosen for harsh conditions because of their ability
to withstand rough waters.
A semisubmersible is a MODU designed with a platform-type deck that
contains drilling equipment and other machinery supported by pontoon-type
columns that are submerged into the water. Another type of drilling rig that
can drill in ultra-deepwaters, drillships are capable of holding more
equipment; but semisubmersibles are chosen for their stability. The design
concept of partially submerging the rig lessens both rolling and pitching on
semisubs.

5. While in transit, semisubs are not lowered into the water. Only during drilling
operations are semisubs partially submerged. Because semisubs can float
on the top of the water, transporting these rigs from location to location is
made easier. Some semis are transported via outside vessels, such as tugs
or barges, and some have their own propulsion method for transport.

6. Types Of Semisubs
Source : https://en.wikipedia.org/wiki/Semi-
submersible_platform#/media/File:Deepwater_drilling_systems_2.png
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24

7. Based on the way the rig is submerged in the water, there are two main types of
semisubmersibles: bottle-type semisubs and column-stabilized semisubs.
Bottle-type semisubs consist of bottle-shaped hulls below the drilling deck that can
be submerged by filling the hulls with water. The first incarnation of this type of
drilling rig, bottle-type semisubs originally were conceived as submersible rigs. As
a submersible, the bottles below the rig were completely submerged, resting on the
ocean floor.

8. But, as time progressed, naval architects realized that the rig would maintain
its stabilization if the bottles were only partially submerged, but be able to
drill in deeper waters. Mooring lines are then used to keep the semisub in
place, and these anchors are the only connection the rig has with the sea
floor. Eventually, these bottle-type rigs were designed to only serve as
semisubs.

9. As a semisub, the rig offered exceptional stability for drilling
operations, and rolling and pitching from waves and wind was
great diminished. In addition to occasional weather threats, such
as storms, cyclones or hurricanes, some drilling locations are
always harsh with constant rough waters. Being able to drill in
deeper and rougher waters, semisubs opened up a new avenue
for exploration and development operations.

10. DSS 38 Semisubmersible
Source:
https://www.rigzone.com/training/insight.asp?insight_id=338&c_id=
24

11. A more popular design for semisubmersible rigs is the column-
stabilized semisub. Here, two horizontal hulls are connected via cylindrical
or rectangular columns to the drilling deck above the water. Smaller diagonal
columns are used to support the structure.
Submerging this type of semisub is achieved by partially filling the horizontal
hulls with water until the rig has submerged to the desired depth. Mooring
lines anchor the rig above the well, and dynamic positioning can help to
keep the semisub on location, as well.

12. Mooring Patterns (padrões de amarração)
Semisubmersibles and other mobile offshore facilities are moored in
systematic ways, but there are many different designs for various situations.
Mooring is similar to multiple anchors, and a number of spread mooring
patterns are used to keep the floating rig in place, including symmetric six-
line, symmetric eight-line, symmetric twelve-line and 45i-90i nine-line,
among others. These mooring spreads are chosen depending on the shape
of the vessel being moored and the sea conditions in which it will be
moored.

13. Because the wellbore is extremely precise, it is very important that the
semisub is kept in position, despite the waves and the winds working to
move it about. Furthermore, working in ultra-deepwaters, the drilling riser
pipe may span thousands of feet from the bottom of the semisub to the
stationary subsea well equipment located on the ocean floor.

14. The drilling equipment is somewhat flexible to overcome slight movements
caused by the wind and waves, but the drilling risers must not be bent
beyond what it can manage, or they will break.
Additionally, dynamic positioning can be used as well as mooring lines to
keep the rig in place. Dynamic positioning uses different motors or
propulsion units on the vessel to counteract against the motions of the
water.

15. Many times, the dynamic positioning system is guided by telemetry signals
from beacons on the ocean floor, satellite information and the angular
movements of a cable.

16. Loggin While Drilling LWDSource: Leg Summaries & Maps

17. • For centuries, drillers (whether drilling for oil or water) have been keeping
keen notes of drilling activities. What started as a regular record of drilling
depth versus cuttings observed (also known as mud logging) has
transformed to encompass various technological well logging
measurements, including electric logging, SP, induction and GR. Most
recently, scientists and engineers have developed Logging-While-Drilling
(LWD), a type of well logging that incorporates the logging tools into the
drill string, administering, interpreting and transmitting real-time
information measurements to the surface.

18. •
• Overcoming well logging challenges presented by directional drilling, LWD
has revolutionized the well logging concept. By locating well logging tools
near the drill bit on the end of the drilling apparatus, LWD enables drillers
to log wells that exceed 60 degrees, which makes pushing the tool through
the well impossible. Additionally, by providing real-time information, LWD
helps drillers and engineers to make immediate decisions about the future
of a well and the direction of drilling.

19. Providing information on porosity, resistivity, acoustic waveform, hole direction, and
weight on bit, LWD transmits logging measurements at regular intervals while drilling is
taking place. Data is transmitted to the surface through pulses through the mud column
(also known as mud pulse of mud telemetry) in real time.
A type of LWD, Measurement-While-Drilling (MWD) specifically refers to information
used to help in steering the drill, such as direction, orientation and drill bit information.

20. Drillers and engineers are able to use LWD information immediately to
define well placement and predict drilling hazards. Known as "intelligent
drilling," use of real-time logging information provided by LWD is enabling
stronger, more successful wells both onshore and off.

22. C:UsersengliOneDriveOxford English for Careers Oil and Gas 1 Student's Book CD.mp3

27. Bibliógrafia Oil and Gas 1 Student's Book by Lewis Lansford,
D'Arcy Adrian-Vallance, Peter Astley
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de 2021