Wellbore Cleanout and Scale Removal

Exercises Wellbore Cleanout and Scale Removal

1. Can scale inhibitors be placed in acid solutions?

1. Yes
2. No
3. Some inhibitors can

Solution

3. Some inhibitors can

2. Which acid system is best suited for removing iron sulfide scale from the wellbore and perforations?

1. 10 % HCl with sequestering agents
2. 10 % acetic acid
3. 15 % HCl-aromatic dispersion
4. 7 1/2 % HCl with no surfactant

Solution

1. 10 % HCl with sequestering agents

3. All acid-insoluble scales cannot be removed chemically.

1. True.
2. False.

Solution

2. False (Calcium sulfates can be removed with converter solutions).

4. How do liquid scale inhibitors work?

1. By dissolving in formation fluids during placement.
2. By coating the tubulars.
3. By balancing the chemical equilibrium.
4. By adsorbing on the rock surface and being produced gradually.

Solution

4. By adsorbing on the rock surface and being produced gradually

Assessment Wellbore Cleanout and Scale Removal

1. Hydrocarbons such as xylene or toluene are preferred over diesel when applying a mutual solvent to a dry gas reservoir.

A .True. ✔
B .False.

2. Soaking the perforations with acid is less expensive than pumping acid into the formation.

A .True. ✔
B .False.

3. Calcium Sulfate is _________.

A .water soluble.
B .acid soluble.
C .acid insoluble. ✔

4. An acid insoluble material is treated by_________.

A .acidizing then converting.
B .converting then acidizing. ✔
C .neither of these.

5. The formation of scale can be inhibited within the rock matrix so an acid job will not have to be performed later.

A .True ✔
B .False

6. A well treating program calls for a mutual solvent and acid job. Which is pumped first?

A .The mutual solvent. ✔
B .The acid.

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