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Log Analysis- Eval 305- Log Analysis Fundamentals > eval module 2 & 3 > Flashcards

eval module 2 & 3 Flashcards

0
Q

What does Rt mean

A

True formation Resistivity.

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1
Q

Name the six basic logs that the triple combo and platform express use

A 
Resistivity
Sonic porosity
Neutron density porosity
Gamma ray
Sp
Calliper
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2
Q

What is the Archie equation ?

A

SW=(f*Rw)/Rt)^1/n

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3
Q 
What are the API gravity ranges for
Light 
Medium
Heavy
Extra heavy
A

Light > 31
Medium 22 - 31
Heavy 10 - 22
Extra heavy < 10

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4
Q

Define water saturation

A

The percentage of the pore space that is occupied with formation water. Calculated using the Archie equation.

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5
Q

What is the formula for calculating oil reserves

A

Effective porosity * area * thickness * oil saturation * Bo * Rf

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6
Q

What are porosity and lithology derived from

A

Sonic log
Compensated neutron formation density log
The core

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7
Q

Rw measurements are made on water samples recovered from ?

A

DSTs and production tests

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8
Q 
Archie equation variables
Sw
F
Rw
Rt
n
A 
Sw=water saturation
F=formation Resistivity factor
Rw=formation water Resistivity
Rt=true formation Resistivity 
n=saturation exponent ---- usually 2
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9
Q

Is F gay? If so what is it’s formula?

A

F=a/porosity^m

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10
Q

What is m in the formation factor equation ??????????!!!!?!!!?!???!!!?!

A

The cementation exponent
Varies with grain specifics
And tortuosity (complexity of paths between pores)

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11
Q

What is the normal value for tortuosity(a)?….

A

O
N
E

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12
Q

What is the normal value for the cementation exponent (m)?

A

T
W
O

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13
Q

The Archie equation must always be corrected to what?

A

The formation temperature (Tf)

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14
Q

what is Rt

A

The true Resistivity of the fluid filled formation in the uninvaded zone.

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15
Q

What is absolute permeability?

A

permeability of a single phase fluid

16
Q

What is effective permeability?

A

The ability of a porous medium to transit a fluid in the presence of more than one phase.

17
Q

What are the factors affecting relative permeability?

A

Fluid saturation
geometry and size distribution of the pore spaces
Wettability
Fluid saturation history

18
Q

What is capillary pressure?

A

The pressure requires to squeeze a hydrocarbon droplet through a pore throat to overcome the interfacial tension between oil and water phases. Capillary pressure is higher for smaller pore spaces.

19
Q

What is wettability?

A

measure of the relative preference of the pore surface of rocks to be covered by a certain phase and is affected by the minerals present in the pores.

20
Q

What is a water wet rock?

A

a rock with much more affinity for water than oil

21
Q

What is intermediate wettability?

A

occurs when some pores are water wet and some are oil wet

22
Q

Most kind of water do most reservoir sands contain?

A

Connate waters (present in pores at time of deposition)

23
Q

How is temperature formation measured?

A

bottom-hole temperature logs

24
Q

What is the assumption for temperature formation?

A

that there is linearity of the geothermal gradient

25
Q

What are the two main reasons Formation temperature is an important characteristic of subsurface rocks?

A

Tool measurements that are sensitive to temperature need to be corrected
The temperature may be used as an indicator of source rck maturity.

26
Q

Define Darcy’s law?

A

rate of fluid flow through a porous medium is proportional potential energy gradient within that fluid. e.g.. compaction/cementation

27
Q

What is diagenesis?

A

post-depositional process in which sediments are exposed to physical, chemical and biological changes.

28
Q

What factors affect primary porosity?

A 
angularity
packing
sorting
cementing
stress
vugs/fracture
29
Q

Secondary porosity generally develops in which 2 rock types?

A

Sandstones

Shales

30
Q

What are the 3 most important logs in determining if economically recoverable volumes of hydrocarbon are present in the well?

A

Resistivity
Porosity
Gamma Ray

Log Analysis- Eval 305- Log Analysis Fundamentals (9 decks)

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