Module 9- Neutron Density

Question 1

Sandstone with gas

Answer 1

Low GR
Low Neuton (low HI=gas)

Question 2

Sandstone with oil

Answer 2

Low GR
High Neutron (High HI=oil)
High density

Question 3

Sandstone with water

Answer 3

Sandstone with low porosity

Increased density

Question 4

Shale

Answer 4

High GR

High Neutron

Question 5

Neutron log responds to?

Answer 5

H in water and hydrocarbons

Question 6

What is the Neutron log the best for detecting?

Answer 6

gas-bearing strata

Question 7

What does a neutron log read in a gas zone?

Answer 7

anomonously low porosity

Question 8

NPHI in shale?

Answer 8

high across shales

Question 9

NPHI in a limestone scale?

Answer 9

actual porosity in limes

Question 10

NPHI in a sandstone?

Answer 10

reads different porosity than the actual

Question 11

Oil, gas and water HI values?

Answer 11

oil- high
water- high
gas- low

Question 12

What is the shale effect?

Answer 12

An increase in neutron porosity due to the presence of clay (causes error in readings= high HI)

Question 13

How does the neutron tool work?

Answer 13

Bombards the formation with high energy neutrons and measures the hydrogen content of the formation as the neutrons collide with the nuclei of the formation’s atoms

Question 14

A lot of H atoms =?

Answer 14

Increased gamma radiation

Question 15

Compensated neutron logs (CNL) determine?

Answer 15

porosity by assuming the that the reservoir pore spaces are filled with either water or oil and then measure the amount of hydrogen atoms in the pores.

Question 16

CNL are designed to do what?

Answer 16

underestimate the high porosity rocks containing gas, (this created the crossover with density logs)