Introduction to Petroleum Engineering
Michelle_Michy
DrillingOperations.pdf
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
PTRE 201
Introduction to Petroleum Engineering
Drilling Preliminaries
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Lecture Outline
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• Phases in an oilfield life cycle
• Different types of wells drilled in each phase
• An overview of the activities before drilling operations start
• National and international agreements involved in drilling projects
• Governmental regulations
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
1. Exploration: Involves geological, geochemical and geophysical surveys
2. Appraisal: Preliminary development planning, feasibility studies
3. Development: Capital-intensive investments for operational infrastructure
4. Production: Starting to produce hydrocarbon
5. Abandonment: Decommissioning of facility installations
Oilfield Life Cycle
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• Geoscientists predict where the oil and gas occur.
– Geology: Structural and stratigraphic studies
– Geochemistry: Chemistry of petroleum and its sources
– Geophysics: Gravity, magnetic and seismic methodologies
• Existence of a working petroleum system is proved.
– Preliminary business and economic planning
– Define the optimal drilling location
• Drilling starts after all
» geological,
» economic,
» political and
» environmental
conditions are considered and evaluated.
Exploration Phase
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• WildCat Wells
– Drilled in an unexplored and unproven area Might be “Dry Hole”
• Exploratory wells
– Assess if a prospect comprises commercial amounts of hydrocarbon
• Appraisal (step out, delineation) wells
– Determine the size of the field
– Assess the viability of the reservoir
• Developmental wells
– Drilled in the known extent of the field to produce the hydrocarbon
• In-fill wells
– Drilled within the original drilled well patterns
Well-Type Classification
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• The most expensive component in exploration and field development.
• A multidisciplinary project:
– Operating company
– An outside drilling contractor
– One or more service companies
• Health, safety and environmental (HSE)
Drilling Engineering Group Activities:
– Detailed well design, drilling rig selection
– Contractor evaluation and bid requests
– Risk assessment
– Ensuring safe, economic and on schedule operations
Drilling Operations
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• In most countries, all mineral resources belong to the government
• In the United States and parts of Canada, private land has two separate ownerships:
– Surface rights owner
• Can build a house, ranch, or farm on the land
– Mineral rights owner
• Can explore for and produce the gas and oil found on their land
Land Rights
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Lease
A legal document that grants the right to explore, drill and produce oil and gas during the life of the lease.
Signing Bonus
An up-front payment to the owner for granting the lessee a right to explore the property for a limited period of time.
– No exploration or no marketable hydrocarbon Lease expires
– Commercial amounts of hydrocarbon Lease is automatically extended
Royalty
A fraction of the gross revenue from production paid to the owner.
Exploration Lease
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Concession Agreement
• Full control over exploration and production
• Liable for the entire costs and risks
• Pay bonuses, taxes, and royalties to the host country
Production-Sharing Contract
• Full control over exploration and production
• Liable for the entire costs and risks
• An agreed share of the gross production (cost oil) goes towards the costs.
• The remaining production (profit oil) is split between the company and the host country
Service contract
• Contractor is paid a fee for specific services
Production contract
• Contractor takes over an existing or underdeveloped field to improve production
• Portion of the increased production paid to the contractor
Foreign Contracts
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Joint Operating Agreements
• A single well or the development of a larger area
• Reduce the financial impact of a dry hole
• Cost share and production shares are defined and agreed
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Support (Contribution) Agreement
Dry hole agreement
• Cash contribution towards a dry hole
• Receives the geological and drilling information
Bottom hole agreement
• Cash contribution to a certain well depth
• Receives the geological and drilling information
Acreage contribution agreement
• Property lease or interest contribution
• Receives the geological and drilling information
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drilling Contracts
Footage drilling contract
• Based on cost per foot to drill down to contract depth
Daywork contract
• Based on a cost per day to drill down to contract depth
Turnkey contract
• An exact cost to drill down to the contract depth
Combination contract
• Footage rate to a certain depth and daywork rate below that
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Government Regulations Drilling Spacing Unit (DSU)
• A legally described boundary (a square or a rectangle area) around each well
• Typically 40 or 80 acres for oil wells and 640 acres for gas wells.
• Depends on the oil viscosity and reservoir permeability.
• Well can be off center but cannot be located on the edge.
Allowable
• The maximum amount of production allowed from a single well, lease, or field during a specific unit of time.
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drilling Plan
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Authority for expenditure (AFE)
Drilling Prognosis
Drilling engineers & contractors
Technical aspects Expected drill time Cost estimate
Drilling permits acquired
Lease is secured
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Site preparation
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Site is cleared of vegetation and leveled
Below-ground-level cellar is excavated Reserve pit and settling pits for water
or drilling fluid (mud) discharges
Pad for the drilling rig and other equipment is constructed
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Rigging Up
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Rig Crew
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• Company man/Rig Supervisor
• Tool Pusher
• Driller
• Derrick man
• Floormen (Rotary helpers, roughnecks)
• Mud Engineer (Mud Logger)
• Mechanics & Electricians
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Typical Rig Site
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Power
Pipe Racks
Drill Rig
Mud System
Personnel Quarters
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei 19
Mud System
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
PTRE 201
Introduction to Petroleum Engineering
Drilling Mechanics
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
History of Drilling
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Cable Tool Rigs
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• Derrick
• Engine
• Drilling Cable
• Drill Stem
• Drill bit
• Bailer
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Cable Tool Rigs
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Advantages:
• Suitable for remote settings
• Low fuel consumption
• Low capital investment and cheap maintenance
• Efficient use of personnel
• Simple design
Disadvantages:
• Very slow
• Rock chips remain in the hole
• Limited to vertical holes
• Suitable for shallow depths
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Rotary Drilling Rigs
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• Hoisting System
• Rotary System
• Fluid Circulating System
• Power System
• Well Control System
• Well Monitoring System
Rotary Rig Components
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Hoisting system
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• Derrick
• Draw works
• Fast line
• Crown block
• Travelling block
• Dead line
• Deal line anchor
• Storage reel
• Hook
Derrick
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Hoisting System
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
The Rotating System
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– Swivel
– Kelly
– Kelly Bushing
– Master Bushing
– Rotary Table
Drill String Rotates Rotates
Bit
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• Rotary Table: Spinning section of the drillfloor
• Master Bushing: Receives the rotational momentum
• Kelly Bushing: Transfers the rotation to the Kelly
Rotary Mechanism
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• Developed in the 1970s
• Becoming very popular
• More efficient than
conventional rotary systems
Top Drives
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drill String
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• Transmits the rotational movement to the drill bit
• Transmits drilling fluid (via the mud pumps)
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drill Pipe Connection
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Environmentally Friendly Drilling Systems
Virtual Tour of a Drilling Rig
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Drill Pipe Connection
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drill Bit
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• Located at the bottom of the drill string
• Breaks up & dislodges the formation rock
• Common diameters of 3 3/4 to 26 in
• Rotating at a rate of 50-100 rpm
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Blade Bits (Drag, Wing, Fishtail Bits)
– Unconsolidated formations
– Cuts the rock by shearing force
Tricone Bits
– Cuts by crushing and chipping
• Milled teeth – Long toothed for soft formation
– Short toothed for medium hard formations
• Insert or button type – Tungsten carbide implanted on the cone
Drill Bit Types
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Polycrystalline Diamond Compact Bits
• Man-made polycrystalline diamonds attached to the carbide inserts
Diamond Bits
• Industrial diamonds implanted on bit
• Extremely hard formations
• 40-50 times harder than steel bits
Drill Bit Types
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Drill Bits
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
• Drilling Fluid
• Drilling fluid pumps
• Mud pits
• Compressors
• Mud mixing equipment
• Solid removal equipment
The Circulating System
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De-sander and De-silter)
Mud Pump
De-gasser
Vibrating mesh screens (shale shaker)
Mud Mixer
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drilling mud is a mixture of clay with:
• Water (water-based)
• Oil (oil-based)
• Oil and water (emulsion mud)
• Water & a synthetic organic matter (synthetic-based)
Purpose:
• Cool and lubricate the drill bit
• Remove debris and cuttings
• Stabilize the well wall
Drilling Mud
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drilling Mud
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Underbalance Drilling
Mud hydrostatic pressure < Formation pressure
• Reservoir fluids flow into the wellbore
• Sides of the well to cave in
• Equipment trapped
• Blowout
Overbalance Drilling
Mud hydrostatic pressure > Formation pressure
• Prevent reservoir fluids from entering wellbore
• Drilling mud is forced into the surrounding rocks
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei 23
Circulating System
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
The Power System
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Depending on the size of the rig and the drilling depth, one or more diesel engines supply the power to the rig.
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Well Monitoring and Control Systems
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Well Monitoring System:
• Sensors, gauges, indicators, alarms
Well Control System:
• Detect, stop and remove undesired formation fluid in the borehole.
Kick: Undesired entrance of formation fluid into the borehole
Blowout: Uncontrolled release of formation fluids from the well to the surface
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Seal, control and monitor wells to prevent uncontrolled release of formation fluids from the well.
Blowout Preventer (BOP)
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei 27
Well Control
BOP
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
PTRE 201
Introduction to Petroleum Engineering
Drilling Problems
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drilling Problems
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• Junk in hole
• Stuck Pipe
• Lost Circulation
• Formation Damage
• H2S Embrittlement
• Kick and Blowout
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Fish in the Hole
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• Very time consuming and
costly for the operator.
• A side track or a new
borehole may be necessary.
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Fishing Tools
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Wireline spear
Impression block (a weight with soft lead or wax on the bottom)
Washover pipe (washpipe)
Tapered mill reamer Junk mill
Magnets
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Drill String Twist Off
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Causes:
• Rough pipe handling
• Faulty drill string
• Improper torque and stress
• Damage on the drill string
Diagnosis:
• Loss of drill string weight
• Lack of penetration, increased rotary speed
• Reduced pump pressure, increased pump speed
Spear: fits into and grips the inside of the pipe
Overshot: Fits and grips the outside of the pipe
Overshot
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Mechanical Sticking
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• Inadequate hole cleaning
• Unconsolidated formations
• Sloughing shale
• Hole Geometry
• Ledges: Soft rock above and
below the hard rock washed out
• Key seating: The drill pipe wears
a groove in the side of the well
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Mechanical Sticking
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Stuck Pipe
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Mechanical Sticking
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• Locate the stuck point using a stuck-point indicator tool or stuck-pipe log
• Back off: Unscrew the free section of the drill string
• Cut above the stuck point:
- Chemical cutter: Hydrofluoric Acid
- Jet cutter: Shaped explosive charge
- Severing tool: Powerful explosive
• Use fishing tools to remove the stuck pipe
Back off Video
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Differential Pressure
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ΔP = Pmud – Pformation
Pmud = ρgh
ΔP _
+
Overbalanced Drilling
Underbalanced Drilling
ΔP
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Differential Pipe Sticking
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Solution
• Reduce hydrostatic pressure
• Pipe release agents to reduce the surface tension
• Sudden movement of the drill string (Jarring)
Source: www.aapgsuez.net
Jarring
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Lost Circulation
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Drilling fluid flow in > flow out
Causes:
• High formation permeability
• Faults and fractures
• Low formation pore pressure
• Drilling fluid characteristics
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Lost Circulation
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Solution:
• Decreasing circulation rate
• Decreasing mud weight
• Mud additives (fibers, granules)
• Minimizing pressure loss
• Use of casing
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Formation Damage
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• Reduction in formation permeability
- Physical plugging of pores by mud solids
- Migration of fines into pore throats
- Clay swelling in pore spaces
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Abnormal High Pressure
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Reservoir with large, aerial extent:
Depth increase
Overburden pressure increase
Reservoir compacts
Squeezing fluids out of the pore space
Normal hydrostatic pressure is maintained
Isolated reservoirs with limited extent:
Depth increase
Overburden pressure increase
Seal prevents the fluids to expel from the pore space
Fluid pressure increases
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Kick and Blowout
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Kick: Undesired entrance of formation fluid into the borehole
Blowout: Uncontrolled release of formation fluids from the well to the surface
Formation fluid
entering the wellbore
Mud pressure is
reduced
Wellbore pressure is
reduced
Indications:
• Out-flow rate increase
• Mud pit volume increase
• Flowing well with pumps off
• String weight change
Causes:
• Insufficient mud weight
• Improper hole fill-up during trips
• Pipe pulling speed
• Lost circulation
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Kick and Blowout
16Source: Oil and Gas Well Drilling and Servicing eTool, www.osha.gov
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
H2S Embrittlement
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Problem:
• H2S corrodes and weakens the metal
• Diffused hydrogen makes steel brittle
Prevention:
• Using drill string with more resistant steel
• Adding chemicals to the drilling mud
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Fishing by Downhole Camera
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Downhole Camera
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Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
A Different Type of Fish in the Hole!
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Fish in the Hole
Introduction to Petroleum Engineering Prepared by Dr Minou Rabiei
Embedded Video Links:
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Fishing Animations:
https://www.youtube.com/watch?v=7-WqVgksKtk
https://www.youtube.com/watch?v=o2Ca6pwr0XY
Downhole Camera:
https://www.youtube.com/watch?v=ZzDrheWDhGw
