Unit 1 - Overview of Drilling Operations Flashcards
What is the maximum depth you are allowed to drill with an Exploration license in the UK?
350m
What do companies do before applying for a productions license?
Let geologists evaluate seismic data, regional geology and info on nearby fields + calculate exploration costs, development costs, oil prices, tax regimes etc.
How can you aquire a production license ?
Buy from government or farm into existing licence
What does it mean to farm into an existing licence?
A company takes over a part of a licence or the whole licence by: - paying a sum of money to the licencee - drilling wells on behalf of licencee at own expense - buying the company, who owns the licence
What are the targets of exploration well drilling?
- Determination of HC- presence - Provision of geological data (cores, logs) - Flow tests, to determine production potential and receive fluid examples
Lifecycle of an oil and gas field?
- Exploration - Appraisal - Development - Maintenance - Abandonment
What will a company do if they found an economically attractive discovery?
They enter the appraisal phase → more seismic, more wells, more info
What does a company have to do once they consider a prospect to be financially attractive?
They have to submit a field development plan for approval to the Secretary of State of Energy
What will a company do once they receive approval for the field development?
Start drilling development wells and start the construction of production facilities
What is an operator?
the oil company, who manages the drilling and/or production operations → in joint ventures only 1 company is the operator → normally an oil company employs a drilling contractor
If you have a drilling contractor ? What do they do ?
- employ the personnel for the rig - the own and maintain the drilling rig
What is the task of service companies?
- provide equipment for logging, surveying, etc. - maintain specialist tools or to provide staff
What is a day-rate contract?
- operator prepares detailed well design + program of work for drilling operation - drilling contractor provides drilling rig and personnel - consumable items (drillbits, etc.) provided by operator - contractor is paid a fixed sum for every day of drilling
What is a turnkey contract?
- drilling contractor designs well and contracts transport and support services - contractor purchases well consumables - oil company is charged a fixed sum of money for the whole operation
What is the role of the operator in the case of a turn-key contract?
- specify the drilling targets - evaluation of procedures - establish quality controls on final well
Who is always responsible for the maintenance of the rig and the equipment? No matter the contract?
Always the drilling contractor
What is a “company man”?
A representative of the operator on the rig
Who would hire a tool pusher ?
Drilling contractor
A typical drilling crew consists of ?
Head of the crew: driller Crew: - Derrickman ( also takes care of pumps) - 3 roughnecks - mechanic - electrician - crane operator - roustabouts (general labourers)
What is a drilling proposal ?
Prepared by the geologists and reservoir engineers → provides information upon which well will be designed and the drilling program will be prepared. proposal contains: • Objective of the Well • Depth and Location of Target • Geological Cross section • Pore Pressure Profile Prediction
What is the drilling program?
Prepard by the drilling engineer contains: - drilling rig - location for rig - hole sizes + depths - casing sizes + depths - drilling fluid specifications - directional drilling info - well control equipment and procedures - bits and hydraulics program
Why do BOPs have a large inner diameter?
So that necessary drilling tools can be run in the hole
How do you call tools to measure petrophysical logs, that are run on an eletric wireline?
Wireline logging tools
What is the percentage of oil and gas produced from offshore fields ?
25%
Decription of a Jack-up rig?
- Has retractable legs
- Up to 350 ft. water depth
Drill depth of a semi-submersible platform?
- is not bottom supported → floats
- up to 3500 ft water depth
When are drillships used ?
For very deep water → up to 7500 ft.
Why is the rig connected to seabed once it is not a fixed drilling platform?
you would have a constant position change → drillpipe should shear
Is there still work for the rig once the development wells have been drilled?
yes:
- maintenance of the wells
- redrill to intersect another part of the reservoir
- possibility of converting from a producer well to a gas/water injector well
Why are offshore wells more expensive than onshore wells?
- specially designed rigs
- subsea equipment
- bad weather means time loss
- transport costs (e.g. helicopters, boats)
What is the contribution of the drilling costs to the whole development costs for an offshore field?
- 25 - 35%
Which drilling costs are related to time?
For example:
- drilling contract
- transport
- accomodation
Which item costs are related to depth?
consumable items (e.g. casing or cement)
→ can be estimated from the drilling program
Which items are fixed costs ?
Wellhead for example
What happens once the cost estimation (AFE) is done?
It needs to be send to the company managment for approval
What is an AFE?
Authority for expenditure - a document, which lists the estimated cost for drilling a well to a specified depth
