Introduction and Rock Properties

Question 1

What is a hydrocarbon?

Answer 1

Hydrocarbons are a class of organic compounds consisting predominantly of hydrogen (H) and carbon (C), with traces of nitrogen (N), oxygen (O) and sulphur (S).(methane, ethane, butane, polypropylene)

Question 2

What are the 4 main things a Reservoir Engineer must determine when there is a known hydrocarbon in a reservoir?

Answer 2

–How much hydrocarbon is in place?
–How much of the hydrocarbon can be recovered?
–What is the timeline for the recovery process?
–How much profit can be achieved?

Question 3

What are the 4 stages of analysis?

Answer 3

–Understand the physics of the problem (e.g., properties and behaviour of hydrocarbon).
–Collect the required data (field and experimental tests, literature, professional judgment).
–Apply a suitable model to predict performance results
–Verify and evaluate the model results using other models and real data.

Question 4

What are the two main area’s Reservoir engineers traditionally function within:

Answer 4

1. Exploration and development of new pools

2. Optimization of already discovered pools

Question 5

What is Porosity?

Answer 5

• How much solid / how much void

- Volume of Voids / Bulk Volume

Question 6

What is effective porosity?

Answer 6

Volume of INTERCONNECTED PORES / Bulk Volume

Question 7

Primary porosity is the original ____ (interstitial) void space

Answer 7

inter-granular

Question 8

Secondary porosity is void space developed by ______ or ______

Answer 8

fractures, dissolution

Question 9

Dual Porosity

Answer 9

void spaces within rock are made up components with different ORIGINS (inter-granular and fracture; fracture and dissolution)

Question 10

What are the 5 controls on porosity?

Answer 10

Packing-how grains or clasts are packed together.
Sorting-particle size distribution.
Clast porosity-porosity within clasts or fragments.
Fracturing porosity-secondary porosity added by stress and deformation.
Solution porosity-secondary porosity added by solid-fluid interaction.

Question 11

Density log

Answer 11

Measures bulk density of formation. Gamma rays are stopped by electrons -the denser the rock the fewer gamma rays reach the detector

Question 12

Sonic log

Answer 12

Measures time required for compressional sound waves to travel through one foot of formation. Sound travels more slowly in fluids than in solids. Pore space is filled with fluids. Travel time increases as porosity increases.

Question 13

Neutron log

Answer 13

Measures the amount of hydrogen in the formation (hydrogen index). In clean, liquid filled formations, hydrogen index is directly proportional to porosity. Neutron log gives porosity directly.

Question 14

when estimating the volume of a specific pore fluid, we need to know the _____ of the rock as well as the _____state.

Answer 14

porosity , saturation

Question 15

q

Answer 15

specific discharge, (L/T) (has dimensions of velocity but is NOT the flow rate)

Question 16

Q

Answer 16

volumetric flow rate, (L^3/T)

Question 17

A

Answer 17

flow cross section (L^2)

Question 18

K

Answer 18

hydraulic conductivity (L/T)

Question 19

dh/dL

Answer 19

hydraulic gradient

Question 20

K varies empirically as follows:

Answer 20

1. K increases with porous medium grain sized (proportional to d^2)
2. K increases with fluid density (specific weight, g)
3. K decreases with fluid viscosity

Question 21

True or False: 1 md is often used for net-pay cutoff purposes

Answer 21

true

Question 22

Klinkenkerg effect

Answer 22

when the pressure is so low the molecules no longer collide with pore wall - increases flux (permeability is measured abnormally high)