Unit 1 - Overview of Drilling Operations

Question 1

What is the maximum depth you are allowed to drill with an Exploration license in the UK?

Answer 1

350m

Question 2

What do companies do before applying for a productions license?

Answer 2

Let geologists evaluate seismic data, regional geology and info on nearby fields + calculate exploration costs, development costs, oil prices, tax regimes etc.

Question 3

How can you aquire a production license ?

Answer 3

Buy from government or farm into existing licence

Question 4

What does it mean to farm into an existing licence?

Answer 4

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

Question 5

What are the targets of exploration well drilling?

Answer 5

• Determination of HC- presence - Provision of geological data (cores, logs) - Flow tests, to determine production potential and receive fluid examples

Question 6

Lifecycle of an oil and gas field?

Answer 6

• Exploration - Appraisal - Development - Maintenance - Abandonment

Question 7

What will a company do if they found an economically attractive discovery?

Answer 7

They enter the appraisal phase → more seismic, more wells, more info

Question 8

What does a company have to do once they consider a prospect to be financially attractive?

Answer 8

They have to submit a field development plan for approval to the Secretary of State of Energy

Question 9

What will a company do once they receive approval for the field development?

Answer 9

Start drilling development wells and start the construction of production facilities

Question 10

What is an operator?

Answer 10

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

Question 11

If you have a drilling contractor ? What do they do ?

Answer 11

• employ the personnel for the rig - the own and maintain the drilling rig

Question 12

What is the task of service companies?

Answer 12

• provide equipment for logging, surveying, etc. - maintain specialist tools or to provide staff

Question 13

What is a day-rate contract?

Answer 13

• 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

Question 14

What is a turnkey contract?

Answer 14

• 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

Question 15

What is the role of the operator in the case of a turn-key contract?

Answer 15

• specify the drilling targets - evaluation of procedures - establish quality controls on final well

Question 16

Who is always responsible for the maintenance of the rig and the equipment? No matter the contract?

Answer 16

Always the drilling contractor

Question 17

What is a “company man”?

Answer 17

A representative of the operator on the rig

Question 18

Who would hire a tool pusher ?

Answer 18

Drilling contractor

Question 19

A typical drilling crew consists of ?

Answer 19

Head of the crew: driller Crew: - Derrickman ( also takes care of pumps) - 3 roughnecks - mechanic - electrician - crane operator - roustabouts (general labourers)

Question 20

What is a drilling proposal ?

Answer 20

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

Question 21

What is the drilling program?

Answer 21

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

Question 22

Why do BOPs have a large inner diameter?

Answer 22

So that necessary drilling tools can be run in the hole

Question 23

How do you call tools to measure petrophysical logs, that are run on an eletric wireline?

Answer 23

Wireline logging tools

Question 24

What is the percentage of oil and gas produced from offshore fields ?

Answer 24

25%

Question 25

Decription of a Jack-up rig?

Answer 25

• Has retractable legs
• Up to 350 ft. water depth

Question 26

Drill depth of a semi-submersible platform?

Answer 26

• is not bottom supported → floats
• up to 3500 ft water depth

Question 27

When are drillships used ?

Answer 27

For very deep water → up to 7500 ft.

Question 28

Why is the rig connected to seabed once it is not a fixed drilling platform?

Answer 28

you would have a constant position change → drillpipe should shear

Question 29

Is there still work for the rig once the development wells have been drilled?

Answer 29

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

Question 30

Why are offshore wells more expensive than onshore wells?

Answer 30

• specially designed rigs
• subsea equipment
• bad weather means time loss
• transport costs (e.g. helicopters, boats)

Question 31

What is the contribution of the drilling costs to the whole development costs for an offshore field?

Answer 31

• 25 - 35%

Question 32

Which drilling costs are related to time?

Answer 32

For example:

• drilling contract
• transport
• accomodation

Question 33

Which item costs are related to depth?

Answer 33

consumable items (e.g. casing or cement)

→ can be estimated from the drilling program

Question 34

Which items are fixed costs ?

Answer 34

Wellhead for example

Question 35

What happens once the cost estimation (AFE) is done?

Answer 35

It needs to be send to the company managment for approval

Question 36

What is an AFE?

Answer 36

Authority for expenditure - a document, which lists the estimated cost for drilling a well to a specified depth