Zusammenfassung der Ressource
LECTURE 20
- DRILLING
- Types
- Onshore
- Offshore
- Jack-up rig
- able to stand on sea
floor, floated into
place, leg jacked
down onto sea floor
- shallow water, <120m
- Semi-submersible rig
- <= 10,000 feet/ ~3000m
- stable in marine,
watertight
pontoons below
ocean, wave base,
operating deck is
far from waves
connected to
pontoon by
structural columns
- Rotating system
- Rotary table
- Kelly and Kelly bushing
- Drillingstring assembly
- Swivel
- Decoupling of
Kelley
rotation and
circulating
system
- Drill pipe
- steel,
30-33
feet long
- Drill collars
- holds equipment
for logging while
drilling (LWD)
- Measurement
while drilling
(MWD)
- Add weight to
drill bit
- Drill bit
- Tricone drill bit
- Diamond drag
drill bits
- Decrease in well
diameter with
drilling depth
- different bits used for
different hardness of
formation rocks
- Hoisting system
- Derrick
- Drawworks
- Crown block
- Travelling block
- Mud hose (circulating system)
- Circulating system
- Mud
- Circulating - lubrication -
cooling - cleaning of bit -
removal of cutting -
prevent fluids flowing
into well from subsurface
formations + chemical
reaction with subsurface
formations
- mud pump
- Shale shakers
- Remove drill cuttings
from drilling fluid (mud)
- Mud tanks
- Mud volume
- gain
- Blowout
- Blowout preventers (BOPs)
- Lost (lost circulation)
- Fractures
- Fluid invasion of formation
- Conventional drilling program
- Drill - log - case - cement -
change for smaller bit+string
- boost mud weight (density)
- repeat...
- Casing cement in place
- prevent contaminations (fresh water aquifers), unstable formations from caving in
- enable use high density fluids in deep drilling, smooth internal bore for installing equipmnet
- isolate+ seal off high pressure zones
- new joint in mouse hole - swinging the swivel - stabbing the joint - reconnection
- Drill to final/total depth - cement casing & bottom hole assembly - perforate
production well casting at target depths
- Mud log
- Geological interpretation of drill cutting, check rock types vs. prognosis
- Gas detect, composition analysis
- fluorescence (oil)
- Drilling (drilling rate), mud (density, resistivity, viscosity) data
- is basic record of drilling, cutting description of a lithology log
- Deviated wells
- Access issues
- Environmental
- Onshore to offshore areas (cheaper drilling)
- from offshore platforms to many different parts of petroleum field
- Relief well for blowout
- Increased production due to
- Greater intersection with reservoir (thin/low
permeable reservoir
- avoid fluid comming during production by gravity
- intersect/ stimulate fracture network
- Access multiple fuild/pressure compartments
- Coring
- hollow drill bit captures a core (column of rock)
- core slabbed + interpret at surface
- Neotectonic structures (faults, fractures)
- sedimentary strcutures (cross/graded bedding)
- Plugs of core extracted to investigate
- porosity
- permeability
- seal capacity