Fundamentals of Drilling Mud: Section 1

Question 1

Muds are composed of a three phase system:

Answer 1

(1) water (liquid phase)
(2) active solids
(3) inert solids

Question 2

Active Solids

Answer 2

Clays that readily swell in water (Hydrophilic) giving viscosity to the fluid and designated as hydrophilic such as IMCO-Gel (bentonite)

Question 3

Inert Solids

Answer 3

Solids in the drilling mud that do not hydrate or swell in the presence of water (hydrophobic), such as BaSO4, sand, shapes that do not hydrate

Question 4

Hydrophillic

Answer 4

Swell in water

Question 5

Hydrophobic

Answer 5

Does not hydrate or swell in the presence of water

Question 6

What chemical is used to treat mud with a calcium excess of 120 ppm?

Answer 6

Soda ash

Question 7

By increasing the weight the cuttings become more ________ and suspend better, resulting in a cleaner hole

Answer 7

buoyant

Question 8

What is the pressure exerted on a column of fluid at rest called?

Answer 8

Hydrostatic pressure

Question 9

Term used to describe the property of a fluid which causes it to build up a rigid or semi-rigid gel structure when allowed to stand at rest; yet the gel structure can be returned to a fluid state by mechanical agitation.

Answer 9

thixotropic

Question 10

Commercial additives may be broken into two broad categories:

Answer 10

viscosifiers and weighting materials

Question 11

There are two basic types of viscosifiers:

Answer 11

Clays and polymers

Question 12

There are two types of commercial clays:

Answer 12

montmorillonite and attapulgite

Question 13

Montmorillonite clays is used in two forms

Answer 13

Sodium and calcium

Question 14

Sodium montmorillonite is the highest grade of clay and commonly called what?

Answer 14

bentonite (IMCO-gel)

Question 15

Bentonite has the ability to swell up to how many times its size?

Answer 15

10

Question 16

Calcium montmorillonite (IMC-Klay) has the ability to swell up to how many times its size?

Answer 16

2 to 4

Question 17

Which clay yields as much viscosity in salty water as it does in fresh water?

Answer 17

Attapulgite Clay (IMCO-Brine gel)

Question 18

True/False: Attapulgite/Brine gel is good for filtration control

Answer 18

FALSE

Question 19

The term used to describe particle size and ability to remain in suspension

Answer 19

Colloidal

Question 20

True/False: The atomic structure of commercial clays have a negative imbalance thus permitting water to pull it apart

Answer 20

TRUE

Question 21

Which divalent ion is more highly charged than the monovalent sodium ion and forms a stronger bond thus preventing water molecules from swelling the particles to a greater degree?

Answer 21

Calcium montmorillonite (IMCO-Klay)

Question 22

Which clay is harder to pry apart and flocs/aggregates in large units with void spaces between thus limiting the usefulness as a fluid loss reducer and borehole stabilizer?

Answer 22

Calcium montmorillonite (IMCO-Klay)

Question 23

In a sodium chloride solution above __% salt, bentonite becomes impractical for use as a viscosifier. Why?

Answer 23

3. Sodium tends to satisfy the negative imbalance of the particles, bonding the platelets so tightly it produces little hydration or swelling.

Question 24

When bentonite becomes ineffective because of high salt content, which clay is used as a viscosifier?

Answer 24

Attapulgite Clay (IMCO-Brine gel)

Question 25

True/False: Barite, calcium, carbonate and galena are used as viscosifiers

Answer 25

FALSE: weighting materials

Question 26

The most commonly used material for increasing the density of muds is?

Answer 26

Barite (IMCO-Bar), BaSO4

Question 27

Barite has a specific gravity of __ to __. Galena has a specific gravity of __ to __. Calcium carbonate has a specific gravity of __ to __.

Answer 27

4. 2 to 4.3 6. 5 to 6.7 2. 7 to 10.8

Question 28

True/False: Barite is used most often for emergencies such as killing wells.

Answer 28

FALSE: galena

Question 29

Which chemical is used to increase the density of oil muds?

Answer 29

Calcium carbonate

Question 30

What term is defined as the science of flow and deformation of matter (solid, liquid and gas)? In essence, it deals with the study of the ______-______-____ relationship of any matter.

Answer 30

Rheology. stress-strain-time

Question 31

True/False: Viscosity is the most important rheological property of a fluid.

Answer 31

TRUE

Question 32

Capillary viscometer is preferred when the data are used for ____ ____ problems.

Answer 32

Pipe flow

Question 33

___ ________ is a measure of thixotropic under static conditions. It shows the amount of structure buildup during a static period due to the attractive forces between particles. _____ value is a measure of thixotropic under dynamic conditions.

Answer 33

Gel strengths | Yield

Question 34

Starches, CMC, asbestos fibers, and bacterially-grown _______ are under the broad description of which type of viscosifiers

Answer 34

polymer

Question 35

Excessive gel strengths can cause complications such as: 1. __________ of air or gas in the mud, causing a lightening of the __________ column. 2. Pump efficiency _______. 3. Retards settling of sand and cuttings while drilling, causing an ________ in _______ and solids buildup. 4. Swabbing on trips. 5. _________ pressure surges breaking down the formation. 6. Unable to get logging tools to the ______.

Answer 35

1. Entrapment, hydrostatic 2. Reduced 3. Increase, density 5. Excessive 6. bottom

Question 36

True/False. The treatment for excessive gel strengths is not the same for excessive yield point.

Answer 36

FALSE

Question 37

The term for loss of fluid into permeable formations after these zones have been exposed to the drilling fluid through drilling operations.

Answer 37

Filtration or fluid loss

Question 38

True/False: The rate of fluid loss is proportional to the amount of deposited cake.

Answer 38

TRUE

Question 39

Without the deposition of filter cake, dynamic fluid losses are greatest where?

Answer 39

Below the bit

Question 40

True/False: Laminar flow is susceptible to greater fluid loss than turbulent flow (generally adjacent to the drill collars).

Answer 40

FALSE. Turbulent flow is more prone to fluid loss.

Question 41

Which filtration agent has the most favorable filtration control? And which filtration agent helps control dynamic fluid loss rate, particularly at elevated temperatures?

Answer 41

Starch | Lignosulfonate

Question 42

In what ways does temperature effect filtration? 1. Increased __________ 2. Attractive forces ________ with the change in the ionic atmosphere 3. Organic colloids such as ______ and CMC break down under excessive temperatures. 4. High temperatures may cause ___________ in muds containing _______, high alkalinities, and high solids

Answer 42

1. solubility 2. increase 3. starch 4. cementation, calcium

Question 43

True/False: the filter cake becomes more compacted as pressure increases resulting in a change in the cake's porosity and permeability.

Answer 43

TRUE

Question 44

True/False: The addition of dispersants serves to soften the filter cake and thus increase fluid loss.

Answer 44

FALSE. It toughens and lowers

Question 45

Benefits of soda ash:

Answer 45

1. Removes calcium contamination | 2. Decreases viscosity and gel strength