GEORGE KING- ACIDIZING-CAUSES OF FAILURE

Question 1

Acid treatments types can be simplifies into what 3 methods?

Answer 1

1. Wellbore acidizing
2. Matrix acidizing
3. Fracture acidizing

Question 2

Define wellbore acidizing

Answer 2

wash of the wellbore to remove scale on the pipe surface, corrosion and debris.

Question 3

What is the most common acid used for wellbore washes and in what concentration?

Answer 3

HCL 5% to 15%

Question 4

wellbore acid contains what 2 things and why?

Answer 4

inhibitor and some type or surfactant to strip oil from acid reactive surfaces.

Question 5

Name 4 main variables in wellbore acidizing

Answer 5

1. correct treating fluid mixture to target specific material
2. sufficient volume of the treating fluid to accomplish dispersion
3. time of contact that allows reaction to break physical bonding
4. Placement of materials and keeping the materials on the damage

Question 6

Define matrix acidizing

Answer 6

treating of the formation beyond the wellbore to remove permeability blocking damage to inward or outward flow.

Question 7

What are the most common damages?

Answer 7

particulates in injected fluids

Question 8

What are some other causes of damage besides the primary particulate damage?

Answer 8

1. water blocks
2. fine particle migration
3. bacterial colonies

Question 9

What are some damage causes that cannot be removed by matrix acidizing?

Answer 9

poor perforating practice (too few, incorrect placement, uncleaned)
water influx
packer slip
extremely low permeability

Question 10

What is AVR

Answer 10

area to volume ratio

Question 11

How is the reaction within the matrix, fissures or natural fractures controlled?

Answer 11

AVR ratio
AVR ratio hydraulic fracturing 10:1
AVR ratio natural fracture 100:1 to 1000:1
Matrix AVR 20000:1 to 30000:1.

Question 12

Typical concentration of Hcl/HF will range from what for drilling mud removal?

Answer 12

12% HCL and 3% HF

Question 13

Acid fracturing involves fraturing with what acid and in what concentration?

Answer 13

HCL 15%-28%

Question 14

Acid fracturing additives may include:

Answer 14

inhibitor, gelling agents, breakers and surfactant

Question 15

What is the objective of acid fracturing?

Answer 15

to etch stable channels in the fracture face that will stay open when the hydraulic pressure in removed. Soft formations not a good idea!

Question 16

Typical acid etched frac half-lengths are what length?

Answer 16

50 to 100 ft

Question 17

In most comparisons, does proppant fraturing outperform acid fracturing?

Answer 17

YES!!