1. API Mixing Energy Proposal
June 24-28, 2013
Presented by Jim Davison, Ametek-Chandler Engineering
with
Terry Dammel & Joe Day, Schlumberger
Work by Terry Dammel, Schlumberger and Joe Day, Schlumberger

2. Project Goals Assign a Mixing Energy to each Cement Slurry
Step 1 - Laboratory testing with a Lab Blender
Time to reach a vortex at 4000 rpm
Calculate a Mixing Energy value
Step 2 – Field Mixing Equipment
Determine the Mixing Energy of your Field Equipment
Calculate the time needed to Mix the Cement Slurry
This is presentation covers Step 1.
Step 2 is a future study.

3. Parameters Standard API Lab Blender Exception to Standard API Mix
Alter 15 seconds at 4000 rpm
Time mix at 4000 rpm until a stable vortex is reached.
Once a vortex is reached mix at 12,000 rpm for 35 seconds.
Calculate Mixing Energy
The energy needed to hydrate a slurry
API mixing procedure is 15 seconds at 4000 rpm, followed by 35 seconds at 12,000 rpm.
Cement blend should be homogenous particles should be well distributed.

4. Mixing Energy Calculations for the Lab Blender
Standard mixing energy for a laboratory blender. Excel file available for calculations.

5. API Specification 10A
Standard API mixing values. Taken from API Specification 10A, Twenty-Fourth Edition, December 2010, June 1, 2011.

6. Mixing Energy Video
Standard API mixing values. Taken from API Specification 10A, Twenty-Fourth Edition, December 2010, June 1, 2011.

7. Mixing Energy Values
Results from various classifications of A, C, G, H.
The mix water is brought to 4000 rpm and then the timer started when cement powder is added to the mix water.
Timing until a stable vortex is reached.
This time is used to calculate the Mixing Energy to Vortex. The energy needed to hydrate the cement. Kilojoules per Kilograms
API systems should take less than 4000 rpm to reach a vortex, if so we continue mixing for the 15 seconds and then increase the rpm to 12,000 for 35 seconds.
This will result in a Total Mixing Energy of 5.9 kJ/kg.
If it takes longer to reach a vortex, then once the vortex is reached the rpm is increased to 12,000 for 35 seconds. This results in an energy greater than API mix of 5.9 kJ/kg.
NOTE: Density check with an unpressurized mud balance was as follows:
A = 15.4 ppg
C = 14.3 ppg
G = 15.7 ppg
H = 16.4 ppg

8. Mixing Energy Values
Samples H (1-1) indicates Manufacturer 1 from bucket 1. The first two are taken from the same bucket.
Sample H (1-2) indicates Manufacturer 1 from bucket 2 same lot, delivered months later.
Sample H2 indicates Manufacturer 2.
Sample H3 indicates Manufacturer 3.
Questions: Why is more energy needed to mix sample H (1-1)?
Why do the samples from same lot different buckets different?
NOTE: All samples weighted 16.4 pounds per gallon on an unpressurized mud balance.

9. Questions
Why does this brand of Class H cement require a high mixing energy?
Why the difference between two buckets of the same lot?
Will it be able to be mixed in the field?
Will it be able to be pumped on the fly?
Future Questions: Can sample H (1-1) be mixed in the field?
Will the mixing energy be enough to mix it on the fly?
Step 2 is to calculate the energy of your field mixing equipment, then determine how much time is needed to mix the slurry using the Laboratory calculated Mixing Energy.
If too much time is required, than there could be problems mixing and pumping the slurry on the fly.

10. Questions for API How do we know if a cement slurry can be mixed?
Can this procedure be adapted as a part of API testing?
Should 15 seconds at 4000 rpm be applied once a vortex is achieved?
Does documentation in the API determine if a cement slurry can be mixed?
Are you applying mixing energy when the slurry is not hydrated?
Most API slurries should mix in less than 15 seconds.
This will be a quick quality control check on the cement replacing the initial mix rheology which are not recommended by the API.
Slurries with aggregates and additives will usually be more viscous.
This will provide a heads up on potential field problems.