FRAC BALLS TESTING - Bruce Diamond Corp · (Original Signed by) (Original signed by) Mohammad...

FRAC BALLS TESTING

Report Prepared for:

Bruce Diamond Corporation

Prepared by:

Rapid Design Group Inc.

(Original Signed by) (Original signed by)

Mohammad Nauman Serg Arabsky

Technical Services Engineer, E.I.T. President, CEO

August 14, 2012

Nisku, Alberta

FRAC BALL TESTING REPORT

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1. INTRODUCTION

The purpose of this report is to provide a detailed analysis on the pressure test results of Frac

Balls provided by Bruce Diamond Corporation. Rapid Design Group Inc. uses its expertise in

testing Frac Balls and rating them according to their performance under hydraulic pressures. The

Frac Balls are divided into different batches with each batch labeled under different materials.

Those batches are further divided into batches of different sizes and thus, compared to the

exact same size batch in different materials. And the Frac Balls are rated under size batch which

comes under the category of material batch.

1.1 TEST GOALS

Frac Balls are tested to determine:

1. Ball Failure/Maximum Pressure in each batch

2. Ball performance at Failure/Maximum Pressure

3. Ball performance at Holding Pressure

4. Back Pressure after the Holding Pressure

5. Pressure rating due to performance

1.2 TERMINOLOGY

1.2.1 Failure/Maximum Pressure:

The pressure testing equipment is rated to a maximum pressure of 10,000 psi. Therefore, a Frac

Ball is tested until it fails under the hydraulic pressure, Failure Pressure, or until the maximum

pressure is attained if it does not fail.

1.2.2 Ball Failure:

Frac Balls are placed in such a way inside the pressure testing equipment that they create a seal

on the ball sleeve creating a differential pressure i.e.,

Pressure is applied on the top side of a Frac Ball while the bottom side is open to atmosphere. A

Frac Ball fails if the pressure escapes the seal created by the Frac Ball.

1.2.3 Holding Pressure:

Once a Frac Ball has been tested, another Frac Ball of the same batch is tested until the pressure

inside the equipment reaches ~85% of the Failure/Maximum Pressure. The Frac Ball is held at

that pressure for 5-10 minutes.


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1.2.4 Back Pressure:

Depending upon the material and size of a Frac Ball, some either extrude through the ball sleeve

while some crack at the sealing location into 2 halves or break into several smaller pieces.

After the Holding Pressure, the equipment is flipped 180° such that the bottom side becomes

the top side. Pressure is applied, Back Pressure, in order to determine the pressure required to

eject the ball off the ball sleeve. This pressure corresponds to Bottom Hole Pressure, BHP, in the

Downhole Completions industry on field.

2. EQUIPMENT

2.1 Ball Batches for Testing:

- 5 X 3.750” BDC INJECTION MOLDED PEEK

- 1 X 3.750” Extruded PEEK

- 1 X 3.750” Controlled G10

2.2 Testing Apparatus:

- 3 5/8” Seat

- Pressure Testing Unit with ¼” NPT fittings on the end caps

- Stand-alone pressure pumping unit

- Pressure recording system

3. TESTING PROCEDURE

3.1. Initial Failure/Maximum Pressure Test:

- Start pressuring up until the maximum pressure of 10,000 psi is attained or the ball fractures

before reaching the maximum pressure inside the fixture

- Upon fracturing, the bottom end cap with atmospheric relief valve will start leaking

- Record the ball failure/maximum pressure

3.2 Holding Pressure Test:

- Use Frac Ball of a sample that has undergone “Initial Failure/Maximum Pressure Test”

- Pressure up to ~85% of the Failure/Maximum Pressure and hold for 5-10 minutes

- Record the holding pressure and the pressure drop


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3.3 Back Pressure Test:

- Flip the fixture 180° such that the bottom side becomes the top side and interchange the

fittings

- Pressure up to ~85% of the Failure/Maximum Pressure and hold for 5-10 minutes

- Record the holding pressure and the pressure drop

3.4 CF PEEK Balls Placement

- Place the ball dimple facing up on the sleeve and perform 3.1, 3.2 and 3.3 in this orientation

- Place the ball dimple facing sideways on the sleeve and perform 3.1, 3.2 and 3.3

3.5 Controlled G10 Balls Placement

- Place the ball dimple facing up on the sleeve and perform 3.1, 3.2 and 3.3 in this orientation

- From experience and considering the quantity of balls, dimple on the ball represents the

weak orientation and therefore; the weak orientation must be tested first

3.6 Extruded PEEK Placement

- The ball is homogeneous therefore the orientation doesn’t matter


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4. RESULTS AND DISCUSSIONS

4.1 BDC INJECTION MOLDED PEEK

4.1.1. Failure/Maximum Pressure – Dimple up Break 1

Figure 1 - 3.750" BDC injection molded PEEK - Dimple up Break 1 @ 4,173 psi

The ball had a sharp break establishing its failure at 4,173 psi, Figure 1. The ball came off the

seat easily with very little effort, Figure 2.

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3.750" BDC INJECTION MOLDED PEEK - DIMPLE UP BREAK 1

Ball Fail = 4,173 psi


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Figure 2 - 3.750" BDC injection molded PEEK Break @ 4,173 psi

4.1.2. Failure/Maximum Pressure – Dimple up Break 2

Figure 3 - 3.750" BDC INJECTION MOLDED PEEK - Dimple up Break @ 3,763 psi

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3.750" BDC INJECTION MOLDED PEEK - DIMPLE UP BREAK 2

Ball Fail = 3,762.8


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The ball had a sharp failure dimple up, like before, at 3,763 psi. The ball came off the seat easily

with very little effort.

Figure 4 - 3.750" BDC INJECTION MOLDED PEEK Ball – Dimple up break @ 3,763 psi


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4.1.3. Failure/Maximum Pressure – Dimple on side Break 1

Figure 5 - 3.750" BDC INJECTION MOLDED PEEK Ball - Dimple on side break @ 4,878 psi

When the ball was tested in the orientation when the dimple faced the side wall of the sleeve,

the ball broke at higher pressure i.e., 4,878 psi, Figure 5. However, instead of the ball losing

pressure it started to gain pressure. The fixture was flipped 180° and was back pressure

however; the pressure could not be built up. Upon inspection, it was noticed that the ball was

broken in half and the bottom half flipped inside the sleeve getting stuck which explained the

uncommon pressure graph. The ball had to be pressed out of the seat on a hydraulic press.

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3.750" BDC INJECTION MOLDED PEEK BREAK - DIMPLE ON SIDE 1

Ball Fail = 4,878 psi


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Figure 6 - 3.750" BDC INJECTION MOLDED PEEK Dimple on side break @ 4,878 psi

4.1.4. Failure/Maximum Pressure – Dimple on side Break 2

Figure 7 - 3.750" BDC INJECTION MOLDED PEEK Dimple on side break @ 4,893 psi

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3.750" BDC INJECTION MOLDED PEEK - DIMPLE ON SIDE BREAK 2

Ball Fail = 4,892.8 psi


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Figure 8 - 3.750" BDC INJECTION MOLDED PEEK dimple on side break @ 4,893 psi

The ball was tested in this orientation again and similar results were noticed. It was

further noticed that the bottom half was stuck at the dimple ends against the sleeve

walls. Also, the crack occurred at the plane parallel and slightly above the two dimples.

One of the reasons could be that the manufacturing induced pressure traps at the

dimple locations and as soon as cracks appeared at that plane, pressure traps got

released and the ball slightly extruded outward. Hence, the ball got stuck at the two end

points surfaces.

The ball bottom half flipped at about 45°, crack plane with the vertical axis. This could

be understood such that there were two actions happened simultaneously. Firstly, as

the first crack appeared at the sealing location which also happened to be roughly at the

same plane explained above, it propagated across the diameter of the ball. Secondly,

the escaping pressure flipped the bottom half inside the seat getting stuck. The top half

remained in the same orientation after the test as it was placed before the test.

The two different orientation tests show that the ball has a weak and strong orientation,

and pressure-wise the ball is non-homogeneous. Therefore, dimple up is weak

orientation.


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4.1.5. Holding Pressure – Dimple up

Figure 9 - 3.750" BDC INJECTION MOLDED PEEK Ball Holding Pressure

It can be seen that the ball holding pressure plateaued at around 3,000 psi on its weak

orientation, Figure 9. Had the ball been held at 3,500 psi it would have shown similar results,

Figure 10. Hence, the ball can be rated between 3200-3500 psi.

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3.750" BDC INJECTION MOLDED PEEK BALL - HOLDING PRESSURE

Holding Pressure = 3,360.81psi Δ = 335.65 psi


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Figure 10 - 3.750" BDC INJECTION MOLDED PEEK after Holding Pressure


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4.2 3.750” Extruded PEEK

Figure 11 - 3.750" Extruded PEEK failure @ 3,840 psi

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3.750" EXTRUDED PEEK Failure/Maximum Pressure Chart

Max = 3,840 psi


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Figure 12 - Extruded PEEK failure @ 3,840 psi

It can be seen From Figure 11 that the failure pressure for the ball is 3,840 psi. Due to limited

quantity the ball could not be tested for holding pressure. The ball extruded into the seat as

compared to the 3.750” BDC injection molded PEEK balls. The ball came off the sleeve at city

water pressure.


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4.3 3.750” G10

4.3.1 Failure/Maximum Pressure

Figure 13 - 3.750" G10 failure pressure @ 3,958 psi

It can be seen from Figure 13 that the ball failed at 3,958 psi and the ball breaks into a sharp 2

halves break.

-500

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3.750" G10 Failure/Maximum Pressure Chart - Weak Side

Max = 3,958 psi


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Figure 14 - 3.750" G10 failure @ 3,958 psi


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5. COMPARISON

5.1 3.750” Ball Lowest Failure Pressure

Figure 15 - 3.750" Ball Lowest Failure Pressure Chart

It can be seen from Figure 15 that the BDC INJECTION MOLDED PEEK ball has highest pressure of

all. The pressure shown is the average of the two break pressures at its weak orientation. The

Controlled G10 breaks into 2 halves, which could create problems downhole by getting stuck

into the seat. In the 2 halves break, the bottom half quickly turns 90° due to high pressure force

and thus getting stuck. Once the ball is stuck sideways, pressure can’t build up on the ball sleeve

and therefore, the ball might need to get milled. The BDC INJECTION MOLDED PEEK may have

getting stuck and milling problems if the ball landed at its strong orientation. Also, since the ball

built up pressure after the break it can throw off pumping personnel suggesting something

getting stuck other than the ball.

Extruded PEEK yields into the seat losing seal therefore, pressure can’t build up on the ball such

that it gets pushed through the seat therefore, milling may be required. In this test however,

due to high ductility of the material the ball extruded in such a way that it came out the other

end. More tests may be needed to be done to confirm consistency.

3,840

3,958 3,968

3,750

3,800

3,850

3,900

3,950

4,000

Extruded PEEK Controlled G10 BDC injection molded PEEK

3.750" Ball Lowest Failure Pressure (psi)


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BDC INJECTION MOLDED PEEK ball shows consistency in terms of break pressure, holding

pressure, break and the back pressure. Since the ball outperforms G10 ball therefore, it is a

better ball and has higher pressure rating. The ball is also better because it is lighter than the

G10 ball.

6. CONCLUSION

- BDC INJECTION MOLDED PEEK is a better ball in 3.750” category. It is light and takes higher

pressure. However the dimple side getting stuck into the sleeve could create problems.

- Extruded PEEK extrudes through the seat and it has slightly lower pressure than BDC

INJECTION MOLDED PEEK. More tests are needed to be done on this material to confirm

extrude through exit consistency. However, there is a chance that the ball may get stuck

into the seat.

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