Transcript Coastal and Marine Resources Management

TEKNOLOGI RESERVOIR
K04
PEKERJAAN PEMBORAN
(drilling rig, drilling mud, casing, completion,
production, abandonment)
Dr. Wahyudi
Dept. Ocean Engineering, ITS
Surabaya
1. DRILLING RIG
1. Mud tank
15. Monkey board
2. Shale shakers
16. Stand (of drill pipe)
3. Suction line (mud pump) 17. Pipe rack (floor)
4. Mud pump
18. Swivel
5. Motor or power source
19. Kelly drive
6. Vibrating hose
20. Rotary table
7. Draw-works
21. Drill floor
8. Standpipe
22. Bell nipple
9. Kelly hose
23. Blowout preventer (BOP) Annular
10. Goose-neck
24. Blowout preventers (BOPs) Pipe ram
& Blind ram
11. Traveling block
25. Drill string
12. Drill line
26. Drill bit
13. Crown block
27. Casing head
14. Derrick
28. Flow line
1. Drilling rig
• #22 (bell nipple): a section of large diameter pipe fitted to the top of the
BOPs that the flow line attaches to via a side outlet, to allow the drilling fluid
to flow back to the mud tanks.
• #23 & #24 (blowout preventers BOPs): are devices installed at the wellhead
to prevent fluids and gases from unintentionally escaping from the wellbore.
#23 is the Annular (often referred to as the Hydril, which is one
manufacturer) and #24 is the Pipe rams and Blind rams.
• Casing head: (#27) a large metal flange welded or screwed onto the top of
the conductor pipe (also known as drive-pipe) or the casing and is used to
bolt the surface equipment to. Equipment such as the blowout preventers (for
well drilling) or the christmas tree (for well production).
• Centrifuge: (Not pictured) an industrial version of the device that separates
fine silt and sand from the drilling fluid. Typically mounted on top or just off
of the mud tanks.
• Crown block: (#13) The stationary end of the block and tackle.
1. Drilling rig
• Degasser: (Not pictured) a device that separates air and/or gas from the
drilling fluid. Typically mounted on top of the mud tanks.
• Derrick: (#14) the support structure for the equipment used to lower and
raise the drill string into and out of the wellbore.
• Desander / desilter: (Not pictured) contains a set of Hydrocyclones that
separate sand and silt from the drilling fluid. Typically mounted on top of the
mud tanks.
• Draw-works: (#7) is the mechanical section that contains the spool, whose
main function is to reel in/out the drill line to raise/lower the traveling block.
• Drill Bit: (#26) device attached to the end of the drill string that breaks apart
the rock being drilled. It contains jets through which the drilling fluid exits.
• Drill floor: (#21) the area on the rig where the tools are located to make the
connections of the drill pipe, bottom hole assembly, tools and bit. It is
considered the main area where work is performed.
1. Drilling rig
• Drill line: (#12) Thick, stranded metal cable threaded through the two blocks
(traveling & crown) to raise and lower the drill string.
• Drill Pipe: (#16) joints of hollow tubing used to connect the surface equipment to the
bottom hole assembly (BHA) and acts as a conduit for the drilling fluid. In the
diagram, these are stands of drill pipe which are 2 or 3 joints of drill pipe connected
together and stood in the derrick vertically, usually to save time while Tripping pipe.
• Drill string: (#25) an assembled collection of drill pipe, heavy weight drill pipe, drill
collars and any of a whole assortment of tools, connected together and run into the
wellbore to facilitate the drilling of a well. The collection of which is referred to
singularly as the drill string.
• Elevators: (Not pictured) a hinged device that is used to latch to the drill pipe or
casing to facilitate the lowering or lifting (of pipe or casing) into or out of the
wellbore.
• Flow line: (#28) is large diameter pipe that is attached to the bell nipple and extends
to the shale shakers to facilitate the flow of drilling fluid back to the mud tanks.
• Goose-neck: (#10) thick metal elbows connected to the swivel and standpipe that
supports the weight of and provides a downward angle for the kelly hose to hang
from.
• Kelly: (#5) a square, hexagonal or octagonal shaped tubing that is inserted through
and is an integral part of the rotary table that moves freely vertically while the rotary
table turns it.
1. Drilling rig
• Drill line: (#12) Thick, stranded metal cable threaded through the two blocks
(traveling & crown) to raise and lower the drill string.
• Drill Pipe: (#16) joints of hollow tubing used to connect the surface equipment to the
bottom hole assembly (BHA) and acts as a conduit for the drilling fluid. In the
diagram, these are stands of drill pipe which are 2 or 3 joints of drill pipe connected
together and stood in the derrick vertically, usually to save time while Tripping pipe.
• Drill string: (#25) an assembled collection of drill pipe, heavy weight drill pipe, drill
collars and any of a whole assortment of tools, connected together and run into the
wellbore to facilitate the drilling of a well. The collection of which is referred to
singularly as the drill string.
• Elevators: (Not pictured) a hinged device that is used to latch to the drill pipe or
casing to facilitate the lowering or lifting (of pipe or casing) into or out of the
wellbore.
• Flow line: (#28) is large diameter pipe that is attached to the bell nipple and extends
to the shale shakers to facilitate the flow of drilling fluid back to the mud tanks.
• Goose-neck: (#10) thick metal elbows connected to the swivel and standpipe that
supports the weight of and provides a downward angle for the kelly hose to hang
from.
• Kelly: (#5) a square, hexagonal or octagonal shaped tubing that is inserted through
and is an integral part of the rotary table that moves freely vertically while the rotary
table turns it.
1. Drilling rig
• Kelly hose: (#9) is a flexible, high pressure hose that connects the standpipe
to the kelly (or more specifically to the gooseneck on the swivel above the
kelly) and allows free vertical movement of the kelly, while facilitating the
flow of the drilling fluid through the system and down the drill string.
• Monkey board: (#15) the structure used to support the top-end of the stands
of drill pipe vertically situated in the derrick.
• Mud motor: (Not pictured) a hydraulically powered device positioned just
above the drill bit used to spin the bit independently from the rest of the drill
string.
• Mud pump: (#4) reciprocal type of pump used to circulate drilling fluid
through the system.
• Mud tank: (#1) often called mud pits, provides a reserve store of drilling fluid
until it is required down the wellbore.
• Pipe rack: (#17) a part of the drill floor (#21) where the stands of drill pipe
are stood upright. Typically made of a metal frame structure with large
wooden beams situated within it. The wood helps to protect the end of the
drill pipe from damage.
• Rotary table: (#20) rotates, along with its constituent parts the kelly and kelly
bushing, the drill string and the attached tools and bit.
1. Drilling rig
• Shale shaker: (#2) separates drill cuttings from the drilling fluid before it is
pumped back down the wellbore.
• Stand: (#16) sections of 2 or 3 joints of drill pipe connected together and
stood upright in the derrick. When pulling out of the hole, instead of laying
down each joint of drill pipe, 2 or 3 joints are left connected together and
stood in the derrick to save time.
• Standpipe: (#8) a thick metal tubing, situated vertically along the derrick, that
facilitates the flow of drilling fluid and has attached to it and supports one
end of the kelly hose.
• Suction line: (#3) intake line for the mud pump to draw drilling fluid from
the mud tanks.
• Swivel: (#18) the top-end of the kelly that allows the rotation of the drill
string without twisting the block.
• Traveling block: (#11) The moving end of the block and tackle, together they
give a significant mechanical advantage for lifting.
• Vibrating hose: (#6) is a flexible, high pressure hose (similar to the kelly hose)
that connects the mud pump to the stand pipe. It is called the vibrating hose
because it tends to vibrate and shake (sometimes violently) due to its close
proximity to the mud pumps.
1. Drilling rig
1. Drilling rig
2. DRILLING MUD
Drilling mud
On a drilling rig, mud is pumped from the mud pits through the drill string
where it sprays out of nozzles on the drill bit, cleaning and cooling the drill bit
in the process. The mud then carries the crushed rock ("cuttings") up the annular
space ("annulus") between the drill string and the sides of the hole being drilled,
up through the surface casing, and emerges back at the surface.
Cuttings are then filtered out at the shale shakers and the mud returns to the
mud pits. The returning mud can contain natural gases or other flammable
materials. These can collect in and around the shale shakers area or in other
work areas.
There is a potential risk of a fire, an explosion or a detonation occurring if they
ignite. In order to prevent this safety measures have to be taken. Safety
procedures, special monitoring sensors and explosion-proof certified equipment
has to be installed, e.g. explosion-proof certified electrical wiring or control
panels. The mud is then pumped back down and is continuously recirculated.
After testing, the mud is treated periodically in the mud pits to give it
properties that optimize and improve drilling efficiency.
Drilling mud
Water-based drilling mud may consist of bentonite clay (gel)
with additives such as barium sulfate (barite), calcium calcium carbonate (chalk)
or hematite.
Various thickeners are used to influence the viscosity of the fluid,
eg. Xanthan gum, guar gum, glycol, carboxymethylcellulose,
polyanionic cellulose (PAC), or starch.
In turn, deflocculants are used to reduce viscosity of clay-based muds;
anionic polyelectrolytes (eg. acrylates, polyphosphates, lignosulfonates (Lig)
or tannic acid derivates such as Quebracho) are frequently used.
Red mud was the name for a Quebracho-based mixture,
named after the color of the red tannic acid salts;
it was commonly used in 1940s to 1950s, then was made obsolete
when lignosulfonates became available.
Many other chemicals are also used to maintain or create some of
the properties listed in the section titled "Purpose".
2. Mud engineer
• The name given to an oil field service company individual who is charged
with maintaining a drilling fluid or completion fluid system on an oil and/or
gas drilling rig. This individual typically works for the company selling the
chemicals for the job and is specifically trained with those products, though
independent mud engineers are still common. The work schedule of the mud
engineer or more properly Drilling Fluids Engineer, is arduous, often
involving long shifts.
• In offshore drilling, with new technology and high total day costs, wells are
being drilled extremely fast. Having two mud engineers makes economic
sense to prevent down time due to drilling fluid difficulties. Two mud
engineers also reduce insurance costs to oil companies for environmental
damage that oil companies are responsible for during drilling and production.
• The cost of the drilling fluid is typically about 10% (may vary greatly) of the
total cost of well construction, and demands competent mud engineers. Large
cost savings result when the mud engineer performs adequately.
• The mud engineer is not to be confused with mudloggers, service personnel
who monitor gas from the mud and collect wellbore samples.
2. Drilling mud: function
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Remove cuttings from well
Suspend and release cuttings
Control formation pressures
Seal permeable formations
Maintain well bore stability
Minimizing formation damage
Cool, lubricate & support the bit and drilling assembly
Transmit hydraulic energy to tools and bit
Ensure adequate formation evaluation
Control corrosion (in acceptable level)
Facilitate cementing and completion
. Remove cuttings from well
• Drilling fluid carries the rock excavated by the drill bit up to the surface. Its ability to
do so depends on cutting size, shape, and density, and speed of fluid travelling up the
well (annular velocity). These considerations are analogous to the ability of a stream
to carry sediment; large sand grains in a slow-moving stream settle to the stream bed,
while small sand grains in a fast-moving stream are carried along with the water. The
mud viscosity is another important property, as cuttings will settle to the bottom of
the well if the viscosity is too low.
• Most drilling muds are thixotropic (i.e. they gel under static condition). This
characteristic keeps the cuttings suspended when the mud is not moving during, for
example, maintenance.
• Fluids that have shear thinning and elevated viscosities are efficient for hole cleaning.
• Higher annular velocity improves cutting transport. Transport ratio (transport velocity
/ lowest annular velocity) should be at least 50%.
• High density fluids may clean hole adequately even with lower annular velocities (by
increasing the buoyancy force acting on cuttings). But may have a negative impact if
mud weight is in excess of that needed to balance the pressure of surrounding rock
(formation pressure), so mud weight is not usually increased for hole cleaning
purposes.
• Higher rotary drill-string speeds introduce a circular component to annular flow path.
This helical flow around the drill-string causes drill cuttings near the wall, where poor
hole cleaning conditions occur, to move into higher transport regions of the annulus.
Increased rotation are the best methods in high angle and horizontal beds.
Suspend and release cuttings
• must suspend drill cuttings, weight materials and additives under a wide
range of conditions.
• drill cuttings that settle can causes bridges and fill, which can cause stuck-pipe
and lost circulation.
• weight material that settles is referred to as sag, this causes a wide variation in
the density of well fluid. More frequently occurs in high angle and hot wells.
• high concentrations of drill solids are detrimental to;
– drilling efficiency (it causes increased mud weight & viscosity which in turn
increases maintenance costs and increased dilution)
– Rate of Penetration (ROP) (increases horsepower required to circulate)
– mud properties that suspended must balanced with properties in cutting removal
by solid control equipment.
• for effective solids controls, drill solids must be removed from mud on the 1st
circulation from the well. If re-circulated, cuttings break into smaller pieces
and are more difficult to remove.
• conduct a test to compare the sand content of mud at flow line and suction
pit (to determine whether cuttings are being removed).
Control formation pressures
• if formation pressure increases, mud density should also be increased, often
with barite (or other weighting materials) to balance pressure and keep the
wellbore stable. Unbalanced formation pressures will cause a blowout from
pressured formation fluids.
• hydrostatic pressure depends on mud weight and True Vertical Depth. If
hydrostatic pressure is greater than or equal to formation pressure, formation
fluid will not flow into the wellbore.
• well control means no uncontrollable flow of formation fluids into the
wellbore.
• hydrostatic pressure also controls the stresses caused by tectonic forces, these
may make wellbores unstable even when formation fluid pressure is
balanced.
• if formation pressure is subnormal, air, gas, mist, stiff foam or low density
mud (oil base) can be used.
• in practice, mud weight should be limited to the minimum necessary for well
control and wellbore stability. If too great it may fracture the formation.
Control formation pressures
Control formation pressures
Seal permeable formations
• when mud column pressure exceeds formation pressure, mud filtrate invades
the formation, and a filter cake of mud is deposited on the wellbore wall.
• mud is designed to deposit thin, low permeability filter cake to limit the
invasion.
• problems occur if a thick filter cake is formed; tight hole conditions, poor log
quality, stuck pipe, lost circulation and formation damage.
• in highly permeable formations with large pore throats, whole mud may
invade the formation, depending on mud solids size;
– use bridging agents to block large opening, than mud solids can form seal.
– for effectiveness, bridging agents must be over the half size of pore spaces
/ fractures.
– bridging agents (i.e calcium carbonate, ground cellulose).
• depending on the mud system in use, a number of additives can improve the
filter cake (i.e bentonite, natural & synthetic polymer, asphalt and gilsonite).
Maintain well bore stability
• chemical composition and mud properties must combine to provide a stable wellbore.
Weight of mud must be within the necessary range to balance the mechanical forces.
• wellbore instability = sloughing formations can cause tight hole conditions, bridges
and fill on trips (same symptoms indicate hole cleaning problems).
• wellbore stability = hole maintains size and cylindrical shape.
• if the hole is enlarged, it becomes weak and difficult to stabilize, causes problems (low
annular velocities, poor hole cleaning, solids loading and poor formation evaluation)
• in sand and sandstones formations, hole enlargement can be accomplished by
mechanical actions (hydraulic forces & nozzles velocities). Reduced by conservative
hydraulics system. Good qualities filter cake containing bentonite to limit the
enlargement.
• in shales, mud weight is usually sufficient to balance formation stress, and wells are
usually stable. With water base mud, chemical differences cause interactions between
mud & shale and can lead to softening. Highly fractured, dry, brittle shales can be
extremely unstable (leading to mechanical problems).
• various chemical inhibitors can control mud / shale interactions (calcium, potassium,
salt, polymers, asphalt, glycols and oil - best for water sensitive formations)
• oil (and synthetic oil) based drilling fluids are used to drill most water sensitive Shales
in areas with difficult drilling conditions.
• to add inhibition, emulsified brine phase (calcium chloride) drilling fluids are used to
reduce water activity and creates osmotic forces prevent adsorption of water by
Shales.
Minimizing formation damage
• skin damage or any reduction in producing formation natural
porosity and permeability (washout)
• most common damage;
– mud or drill solid invade formation matrix
– swelling of formation clays within reservoir, reduce
permeability
– precipitation of solids of mud filtrate to formations fluids or
to the other fluids forming insoluble salts
– mud filtrate & formation fluids forming an emulsion (blocking
reservoir pores)
• specially designed drill-in fluids or workover and completion
fluids, minimize formation damage.
Cool, lubricate & support the bit and drilling assembly
• heat is generated from mechanical and hydraulic forces at the bit and when
drill-string rotates and rubs against casing and wellbore.
• cool and transfer heat away from source and lower to temperature than
bottom hole.
• if not, bit, drillstring and mud motors would fail more rapidly.
• lubricity base on Coefficient of friction. Oil and synthetic bases lubricate
better than water based mud (but can be improved by the addition of
lubricants).
• amount of lubrication provided by drilling fluid depends on type & quantity
of drill solids and weight materials + chemical composition of system.
• poor lubrication causes high torque and drag, heat checking of drillstring but
aware these problem also caused by key seating, poor hole cleaning and
incorrect bottom hole assemblies design.
• drilling fluids also support portion of drill-string or casing through buoyancy.
Suspend in drilling fluid, buoyed by force equal to weight (or density) of
mud, so reducing hook load at derrick.
• weight that derrick can support limited by mechanical capacity, increase
depth so weight of drill-string and casing increase.
• when running long, heavy string or casing, buoyancy possible to run casing
strings whose weight exceed a rig’s hook load capacity.
Transmit hydraulic energy to tools and bit
• hydraulic energy provides power to mud motor for bit rotation
and for MWD (measurement while drilling) and LWD (logging
while drilling) tools. Hydraulic programs base on bit nozzles
sizing for available mud pump horsepower to optimize jet
impact at bottom well.
• limited to:
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pump horsepower
pressure loss inside drillstring
maximum allowable surface pressure
optimum flow rate
drillstring pressure loses higher in fluids higher densities, plastic viscosities
and solids.
• low solids, shear thinning drilling fluids such as polymer fluids,
more efficient in transmit hydraulic energy.
• depth can be extended by controlling mud properties.
• transfer information from MWD & LWD to surface by pressure
pulse.
Ensure adequate formation evaluation
• chemical and physical mud properties and wellbore conditions
after drilling affect formation evaluation.
• mud loggers examine cuttings for mineral composition, visual
sign of hydrocarbons and recorded mud logs of lithology, ROP,
gas detection or geological parameters.
• wireline logging measure - electrical, sonic, nuclear and magnetic
resonance.
• potential productive zone are isolated and performed formation
testing and drill stem testing.
• mud helps not to disperse of cuttings and also improve cutting
transport for mud loggers determine the depth of the cuttings
originated.
• oil base mud, lubricants, asphalts will mask hydrocarbon
indications.
• so mud for drilling core selected base on type of evaluation to
be performed (many coring operations specify a blend mud with
minimum of additives).
Control corrosion (in acceptable level)
• drill-string and casing in continuous contact with drilling fluid
may cause a form of corrosion.
• dissolved gases (oxygen, carbon dioxide, hydrogen sulfide) cause
serious corrosions problems;
– cause rapid, catastrophic failure
– may be deadly to humans after a short period of time
• low pH (acidic) aggravates corrosion, so use corrosion coupons
to monitor corrosion type, rates and to tell correct chemical
inhibitor is used in correct amount.
• mud aeration, foaming and other O2 trapped conditions cause
corrosion damage in short period time.
Facilitate cementing and completion
• cementing is critical to effective zone and well completion.
• during casing run, mud must remain fluid and minimize pressure
surges so fracture induced lost circulation does not occur.
• mud should have thin, slick filter cake, wellbore with no
cuttings, cavings or bridges.
• to cement and completion operation properly, mud displace by
flushes and cement. For effectiveness;
– hole near gauges
– mud low viscosity
– mud non progressive gel strength
Minimize impact on environment ! !!
• Mud is, with varying degree, toxic.
• It is also difficult and expensive to dispose of in an
environmentally-friendly manner.
• Vanity Fair article described the conditions at Lago Agrio, a
large oil field in Ecuador where drillers were effectively
unregulated.
• Texaco, the drilling company, left the used mud (and associated
cuttings and crude oil) in unlined open-air pits, allowing it to
contaminate both surface and underground waters. Storing mud
properly is very expensive.
• After a decade of drilling, Texaco considered transferring the
mud waste at Lago Agrio to concrete-lined pits, but estimated
that it would cost over 4 billion dollars (US).
3. CASING
4. COMPLETION
5. PRODUCTION
6. ABANDONMENT