fractech laboratories - rcp technology · 2.2 bulk density & specific gravity 9 2.3 acid ... a...

FracTech Laboratories

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Unit A, Scotswood Park, Forsyth Road, Sheerwater, Woking, Surrey, GU21 5SU, UK.

Telephone: +44 (0)1483 755244 Facsimile: +44 (0)1483 755285 Email: [email protected] Website: www.fractech.com

FracTech Limited is Incorporated in the UK (No. 2778772)

WARNING: THIS WORK HAS BEEN PERFORMED BY FRACTECH LTD. ON BEHALF OF ITS CLIENT RCP TECH LLC. THE RESULTS ARE

STRICTLY CONFIDENTIAL TO RCP TECH LLC.

DISCLAIMER

WHILST FRACTECH LTD. PERSONNEL HAVE MADE EVERY REASONABLE EFFORT TO CONDUCT THIS STUDY WITH CARE, AND

REPORT THE RESULTS ACCORDINGLY, THE COMPANY CAN ACCEPT NO RESPONSIBILITY FOR ANY EVENT RESULTING FROM THE USE OF THIS DATA, OR OF ANY INTERPRETATION DRAWN FROM THIS DATA.

Report Prepared: 1th July 2013 Report Number 009508A

CONTACT POINT: +44 (0)1483 755244

ISO 13503-2 SUITE

BASELINE FRACTURE CONDUCTIVITY &

PERMEABILITY

CERAMIC PROPPANTS

LtRCP 12/18 and LtRCP 16/20

SUPPLIED BY RCP TECH LLC

FracTech Laboratories

CONTENTS

SUMMARY i

1. EXPERIMENTAL PROCEDURE 1

1.1 Specific Gravity 1

1.2 ISO 13503-2 Method 2

1.3 Compressive Strength Test Procedure 3

1.4 Baseline Fracture Conductivity and Permeability 4

2. RESULTS 7

2.1 Sieve Analysis 7

2.2 Bulk Density & Specific Gravity 9

2.3 Acid Solubility 9

2.4 Sphericity & Roundness 10

2.5 Turbidity 12

2.6 Compressive Strength Test Results 13

2.7 Crush Resistance 14

2.8 Baseline Fracture Conductivity, Permeability &

Pack Width Results 15

APPENDIX A: Proppant Photomicrographs A-1

FracTech Laboratories i

SUMMARY

Two samples of proppant were provided for testing by RCP TECH LLC:

LtRCP 12/18 and LtRCP 16/20.

Testing was carried out in accordance with the API RP 60 & 56 suite and ISO

13503-2 suite of tests, covering crush resistance, acid solubility, bulk density,

specific gravity, sphericity and roundness, turbidity and sieve analysis.

The baseline conductivity and permeability tests of the sample were

performed with a loading of 2lb/ft2, at closure stresses of 2, 4, 6, 8 and 10kpsi,

at 250°F and each maintained for 50 hours between Ohio sandstone.

A summary of results obtained from the API RP 60 & 56 and ISO 13503-2

suite of tests is tabulated overleaf. Long term baseline conductivity results are

presented in the main report.

Photomicrographs are given in Appendix A.

FracTech Laboratories ii

Parameters LtRCP 12/18 LtRCP 16/20

Cru

sh

Tes

t

(ps

i) 10000 7.2 0.4% 7.2 0.1%

12500 12.8 0.4% 11.8 1.6%

Sieve Analysis (90% 12/18)

99.4 0.1

Sieve Analysis (0.1% -30)

0.0 0.0

Sieve Analysis (1% +8)

0.0 0.0

Sieve Analysis (90% 16/30)

75.9 4.9

Sieve Analysis (0.1% -40)

0.0 0.0

Sieve Analysis (1% +12)

0.0 0.0

Mean Size (mm) 1.330 0.000 0.901 0.010

Turbidity (FTU) 56 1 23 1

Sphericity 0.9 0.0 0.9 0.0

Roundness 0.8 0.1 0.7 0.0

Bulk Density (g/cm3)

1.54 0.00 1.71 0.00

Specific Gravity 2.68 0.01 2.90 0.02

Acid Solubility (%) 3.8 0.1 3.5 0.0

Table i: Summary of API RP 60 & ISO 13503-2 Test Suite on Proppant Samples

FracTech Laboratories 1

1. EXPERIMENTAL PROCEDURES

1.1 Specific Gravity

A dry density bottle, with stopper, is weighed (W1). Approximately 30g of

proppant is added and the bottle re-weighed (W2). Mineral oil is added to

cover the proppant and fill the bottle 3/4 full. The bottle is vacuumed to an

absolute pressure of less than 30 mbar for approximately thirty minutes.

More oil is added to fill the bottle. The stopper is then placed in the neck.

Excess oil is wiped off, being careful not to suck oil through the capillary in the

stopper. The full bottle is weighed (W3). The proppant and oil are disposed of

and the bottle refilled with mineral oil only. The stopper is placed in the neck

and the bottle dried and weighed again (W4). This procedure is repeated.

The Specific Gravity is then given by,

(W2 - W1) / ((W4 - W3) + (W2 - W1))


1.2 ISO 13503-2 Methods

The following tests were performed in exact accordance with the ISO 13503-2

procedures. The relevant sections are as follows:

Section Test/Procedure

5.2 Sample Splitting

6 Sieve Analysis

7 Sphericity and Roundness

8 Acid Solubility (tests run using 60% HF as source)

9 Turbidity

10.3 Bulk Density

11 Crush Resistance (with pluviator)*

Table 1: ISO Procedures

*Crush testing was carried out at pressures of 10000 and 12500psi.


1.3 Compressive Strength Testing

40g samples are placed in the cylindrical test cell of diameter 1 inch and

length approximately 2 inches. Steel gauzes enable fluid flow through the

proppant packs. The packs are loaded uniaxially to 100psi. 2%KCl brine at pH

6.5 – 7.5 is flushed through the pack. The stress is increased to required level

(50 or 1050psi) at 100psi/minute with a back pressure of 50psi. The top exit of

the pack is connected to a back pressure regulator. The temperature is

ramped to the required level and held there for 4 or 12 hours.

Figure 1: Compressive Strength Testing Apparatus

After the specified time, the oven is switched off and the stress reduced to

zero. Once cool, the samples are pushed out of the steel holders. They are

dimensioned, weighed and loaded to failure using a servo hydraulic test

machine. From the peak load, the unconfined compressive strength is

recorded.

Gas-Charged

Pressure

Vessel

Piston

Proppant Pack

Steel Tube

1” Ram

BPR

Servo-Pump

Leak Off Line

Convection Oven


1.4 Baseline Fracture Conductivity & Permeability

The Fracture Conductivity Cells allow for samples of proppant of various

loading to be subjected to closure stress and temperature over extended time.

Fluids are flowed through the pack and from differential pressure

measurements the flow capacity of the pack can be determined. A schematic

of the experimental set-up is given below. The cell is essentially a modified 10

square inch API conductivity cell.

Figure 2: Configuration of Conductivity Cell

Proppant Pack

Nitrogen

Deoxygenated

Brine

Needle

Valve

Differential Pressure

Transducer

Thermocouple

Inline Heater &

Silica Saturator

Rock Wafer

Servo-Controlled Axial Stress

Balance


The test procedure is as follows:

1. Outcrop rocks are selected. For these tests, Ohio sandstone was used.

Ohio sandstone has a static elastic modulus of approximately 4 million-psi

and a permeability of 0.1mD. Wafers of thickness 9.5mm are machined to

0.05mm precision and one rock is placed in the cell.

2. The selected proppant is sample split and weighed out. Sample splitting

ensures that a representative sample is achieved in terms of its particle

size distribution.

3. In cell 1, the proppant is placed into the cell and levelled. The top rock is

then inserted.

4. Heated steel platens provide the correct temperature simulation for the

test. A thermocouple inserted in the middle port of the cell wall records the

temperature of the pack. A servo-controlled loading ram provides the

closure stress.

5. The cells were initially set at 80ºF and 1000psi. The cells were then heated

to 250ºF and held for 15 hours at 1000psi before being ramped to 2000psi

over 10 minutes. After 50 hours a set of measurements was made before

the stress was ramped to 4000psi (total time: 115 hours).

6. Further measurements were made at 6000, 8000 and 10000psi,

corresponding to a total time of 265 hours.


Conductivity measurements were made using the following procedure:

i. A 70mbar full range differential pressure transducer is activated by closing

the bypass valve and opening the low pressure line valve (the second

valve is there to prevent fluid flow bypassing the cell itself while the d.p.

bypass is open).

ii. Flow is generated and maintained by a piston pump located downstream

of the cell. The pump can control flow rates down to 10-5cm3/min with a

resolution of 2mm3. Fluid is flowed at rates as specified by the ISO

procedure. When the differential pressure appears to be stable, data is

logged every second for a 3 minute interval. The output from the

differential pressure transducer is fed to a data logger 5 digit resolution

multi-meter.

iii. The mean value of the differential pressure is retrieved from the multi-

meter together with the peak high and low values. If the difference

between the high and low values is greater than the 5% of the mean, the

data is disregarded.

iv. Temperature is recorded from the inline thermocouple at the start and end

of the flow test period. If the temperature variation is greater than 0.5

degrees K the test is disregarded. Viscosity of the fluid is obtained from

using the measured temperature and viscosity tables. For brine at 100psi,

no pressure correction is made. The density of brine at elevated

temperature is obtained from these tables.

v. At least three permeability determinations are made at each stage. The

standard deviation of the determined permeabilities should be less than

1% of the mean value for the test sequence to be considered acceptable.

vi. At the end of the permeability testing, the widths of each of the four

corners of the cell are determined using vernier callipers, to 0.01mm

resolution.


2. RESULTS

2.1 Sieve Analysis

The result of the sieve analysis is tabulated below:

ASTM Mesh

LtRCP 12/18

% Proppant (A) by weight

% Proppant (B) by weight

% Average by weight

Standard Deviation

+8 0.00 0.00 0.0 0.0

-8 +12 0.39 0.55 0.5 0.1

-12 +14 34.39 33.98 34.2 0.3

-14 +16 39.32 39.47 39.4 0.1

-16 +18 25.76 25.87 25.8 0.1

-18 +20 0.07 0.06 0.1 0.0

-20 +30 0.03 0.03 0.0 0.0

-30 0.03 0.03 0.0 0.0

Total 100.0 100.0 100.0

%12/18 99.5 99.3 99.4 0.1

Mean Size(mm) 1.330 1.330 1.330 0.000

Table 2: Proppant: Sieve Analysis, LtRCP 12/18


ASTM Mesh

LtRCP 16/20

% Proppant (A) by weight

% Proppant (B) by weight

% Average by weight

Standard Deviation

+12 0.00 0.00 0.0 0.0

-12 +16 0.22 0.12 0.2 0.1

-16 +18 7.20 5.40 6.3 1.3

-18 +20 72.15 67.07 69.6 3.6

-20 +25 19.83 26.70 23.3 4.9

-25 +30 0.61 0.71 0.7 0.1

-30 +40 0.00 0.00 0.0 0.0

-40 0.00 0.00 0.0 0.0

Total 100.0 100.0 100.0

%16/20 79.3 72.5 75.9 4.9

Mean Size (mm)

0.908 0.894 0.901 0.010

Table 3: Proppant: Sieve Analysis, LtRCP 16/20


2.2 Bulk Density & Specific Gravity

The results of the bulk density & specific gravity are tabulated as follows:

Sample No. Bulk

Density (g/cm3)

Standard Deviation

(g/cm3)

Specific Gravity

Standard Deviation

LtRCP 12/18 1.54 0.00 2.68 0.01

LtRCP 16/20 1.71 0.00 2.90 0.02

Table 4: Bulk Density & Specific Gravity: Results

2.3 Acid Solubility

The results of the Acid Solubility are tabulated below:

Sample No. Test No. % Loss, by Mass

Average % Loss,

by Mass

Standard Deviation

% Loss, by Mass

LtRCP 12/18

1 3.705

3.8 0.1

2 3.815

LtRCP 16/20

1 3.544

3.5 0.0

2 3.505

Table 5: Acid Solubility Results


2.4 Sphericity & Roundness

LtRCP 12/18

Sample Reference Sphericity Roundness

1 0.9 0.9

2 0.9 0.7

3 0.9 0.9

4 0.9 0.9

5 0.9 0.7

6 0.9 0.7

7 0.9 0.7

8 0.9 0.7

9 0.9 0.9

10 0.9 0.7

11 0.9 0.9

12 0.9 0.7

13 0.9 0.7

14 0.9 0.7

15 0.9 0.9

16 0.9 0.9

17 0.9 0.7

18 0.9 0.7

19 0.9 0.7

20 0.9 0.7

Mean = 0.9 Mean = 0.8

Standard

Deviation = 0.0 Standard

Deviation = 0.1

Table 6: Sphericity & Roundness: LtRCP 12/18


LtRCP 16/20

Sample Reference Sphericity Roundness

1 0.9 0.5

2 0.9 0.7

3 0.9 0.7

4 0.9 0.7

5 0.9 0.7

6 0.9 0.7

7 0.9 0.7

8 0.9 0.7

9 0.9 0.7

10 0.9 0.7

11 0.9 0.7

12 0.9 0.7

13 0.9 0.7

14 0.9 0.7

15 0.9 0.7

16 0.9 0.7

17 0.9 0.7

18 0.7 0.7

19 0.9 0.7

20 0.9 0.7

Mean = 0.9 Mean = 0.7

Standard

Deviation = 0.0 Standard

Deviation = 0.0

Table 7: Sphericity & Roundness: LtRCP 16/20


2.5 Turbidity The following table and graph show the spectrophotometer calibration.

Solution/FTU Transmittance/%

0 100.5

40 76.3

80 57.4

120 42.0

160 33.2

200 25.1

240 18.7

280 14.6

320 10.9

400 7.2

Table 8: Turbidity Calibration

Turbidity : Formazin Solutions

0

20

40

60

80

100

120

0 50 100 150 200 250 300 350 400 450

Formazin Turbidity Units / FTU

Tra

nsm

itta

nce

/ %


Sample No.

Measured Sample

Transmittance (%)

Turbidity (FTU)

Mean Turbidity

(FTU)

Standard Deviation

LtRCP 12/18

68.8 55

56 1

67.8 57

LtRCP 16/20

86.8 22

23 1

86.2 23

Table 9: Turbidity Results

2.6 Compressive Strength Test.

The results of the compressive strength tests of the proppant samples are

tabulated below. Samples are run for 4 and 12 hours.

Product Fluid Temperature

(°C)

Curing Stress (psi)

Curing Duration (hours)

Mean UCS (psi)

LtRCP 12/18

2% KCl 20

1000

12 46

2% KCl 35 4 47

LtRCP 16/20

2% KCl 20 12 92

2% KCl 35 4 117

Table 10: Compressive Strength Results


2.7 Crush Resistance

The results of the Crush Resistance tests are tabulated below:

Stress (psi)

LtRCP 12/18

% fines, by mass

Average % fines, by

mass

Standard Deviation (% fines, by

mass)

10000 6.93

7.2 0.4 7.52

12500 12.45

12.8 0.4 13.07

Table 11: Crush Resistance Results, Sample LtRCP 12/18

Stress (psi)

LtRCP 16/20

% fines, by mass

Average % fines, by

mass

Standard Deviation (% fines, by

mass)

10000 7.28

7.2 0.1 7.13

12500 12.93

11.8 1.6 10.68

Table 12: Crush Resistance Results, Sample LtRCP 16/20


2.8 Baseline Fracture Conductivity, Permeability & Pack Width

The results of the baseline fracture conductivity; permeability and fracture

widths are tabulated and plotted below.

Closure Stress (psi)

LtRCP 12/18

Baseline Fracture

Conductivity (mDft)

Baseline Permeability

(Darcy)

Pack Width (mm)

2000 20053 995 6.14

4000 11137 583 5.82

6000 4468 248 5.49

8000 1897 111 5.23

10000 708 42.6 5.06

Table 13: Baseline Conductivity & Permeability Results, 2lb/ft², 250°F, Ohio Sandstone


Closure Stress (psi)

LtRCP 16/20

Baseline Fracture

Conductivity (mDft)

Baseline Permeability

(Darcy)

Pack Width (mm)

2000 8131 462 5.37

4000 6935 403 5.25

6000 5490 326 5.14

8000 3815 231 5.03

10000 2266 141 4.89

Table 14: Baseline Conductivity & Permeability Results, 2lb/ft², 250°F, Ohio Sandstone

FracTech Laboratories A-1

APPENDIX A

Proppant Photomicrographs


Proppant Sample LtRCP 12/18a

Proppant Sample LtRCP 12/18b


Proppant Sample LtRCP 16/20a

Proppant Sample LtRCP 16/20b


Proppant Sample LtRCP 16/20c

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