Technical- Part 7

Question 1

Oil based fluids (YFGO)

Answer 1

GO=gelled oil ; used in water-sensitive formations, expensive

Question 2

What are the Multi-phase fluids

Answer 2

1. Energized fluids = CO2/N2 ; foam <52% ; used in under pressured formations
2. Foams= CO2/N2 ; 52%-96% ; under pressure/water sensitive form, control leakoff
3. Polyemulsions= highly water-sensitive formations

Question 3

Buffer

Answer 3

1. Buffer – used to control pH. (Weak acids or bases)

Question 4

Clay Stabilizers

Answer 4

Clay particles can migrate or swell, blocking the pore spaces and reducing the permeability. The clay stabilizer can be temporary or permanent. Temporary stabilizers prevent swelling or dispersing by maintaining the chemical environment of clay particles. Permanent stabilizers are absorbed on the clay surface bridging the clay particles.

Types: Kaolinite, ilite, chlorite, smecite

Question 5

Bactericides

Answer 5

added to water-based fluids to prevent bacterial degradation of the polymer. Bacteria degrades and lessens the gel’s viscosity.

Question 6

Temperature Stabilizers

Answer 6

used to prevent degradation of gel at temperatures >200°F. Common stabilizers are methanol and sodium thiosulfate. Sodium thiosulfate is more effective than methanol and can maintain gel viscosity @ high temperatures by a factor of 10.

Question 7

Fluid Loss Additive

Answer 7

helps to reduce the loss of fluid into formation, which is needed to propagate cracks in the formation. Fluid additives are pumped during the prePAD and PAD stages.

Question 8

Surfactants

Answer 8

Surfactants – surface-acting agent that reduces the surface and interfacial tensions between the reservoir fluid and treating fluid. They are one part oil soluble and one part water soluble. Used as oil wetters, water wetters, foamers, defoamers, emulsifiers or dispersants. Some of the following are examples:

1. Anionic Surfactant – water soluble group with negative charge
2. Cationic Surfactant – water soluble group with positive charge
3. Nonionic Surfactant – electrically neutral
4. Amphoteric – water soluble group that carries either positive or negative charge
5. Wettability – can be water wet or oil wet

Question 9

Breakers

Answer 9

Breakers – used to degrade the polymer, reducing the fluid viscosity by splitting the polymers into smaller fragments.

Question 10

Corrosion Inhibitor –

Answer 10

Corrosion Inhibitor – slows the attack of acid corrosion on drillpipe, tubing or any other metal that acid contacts during treatment.

Question 11

Iron Control

Answer 11

Iron Control – pH control, sequestering agent or reducing agents to keep iron in solution.

Question 12

Mechanical Obstruction

Answer 12

Ball Sealers – is use to help open up more perforations in the wellbore. The balls can be degradable or rubber. They don’t work always and can lead to screen outs.