Several recommendations can be applied to future project involving ECT sensor to measure porosity, especially in terms of the design. For this project, only eight and twelve electrodes are used to provide image. By opting for sixteen electrodes, a better image can be expected, where the ECT may have chance to locate the porosity distribution of the core sample.
Second, to improve the result of porosity measurement and also the tomogram image for porosity distribution, the methodology may have to be changed. The current methodology, saturating core sample with distilled water may not be suitable to get the accurate result. One suggestion is to inject water at high pressure using the device in figure 24, so that the real time data of water occupying the porous space of the rock can be observed. In fact, along with porosity, permeability can also be detected using ECT.
Measurement electrodes are attached at the outer body of the high pressure water injection device.
FIGURE 24. High pressure water injection device
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Third, by utilizing an industry made ECT sensor may help in the online measurement process. The ECT sensor develop by the student may suffer from performance issue as the ECT are not carefully fabricated, thus resulting in error in measurement. Soldering of the wire and assembling the SMB Plug are the two most challenging aspect of fabricating ECT, therefore the problem may come from both aspects. In addition, the ECT size must be exactly the same size as the core sample, to prevent air from occupying the gap between the core sample and the wall of ECT sensor.
Fourth, to improve the result of measurement using ECT, the core sample size must be according to the standard size used in the industry. Currently, the core sample dimension, 3 inch in length, 1.5 inch in diameter, is too small, thus the ECT may not be able to detect the correct representation of the porosity distribution of the core sample.
Standard size of core sample used in the industry can be obtained from geology or mineralogy lab.
5.3 Future Works
This project will be continued using sixteen electrodes mounted around the external body of the sensor, to provide better image of porosity distribution of core sample. The sensor will also be fabricated by the industry standard to prevent performance issues. In addition, the methodology of the project can also be improved, where the result of image of porosity distribution of core sample can be compared with the result of X-Ray CT scanning. If the ECT is proven to be able to measure porosity distribution in core sample, the ECT can be implemented as a tool that can be used in down hole, to provide real time image of reservoir.
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REFERENCES
1. Ismail, I., Gramio, J.C., Bukhari, S.F.A., Yang, W.Q.,, Tomography for multi- phase flow measurement in the oil industry. Flow Measurement and Instrumentation, 2005(16): p. 145-155.
2. Jenkins, R.J., Accuracy of Porosity Determination, in Core Laboratories, Inc.1960. p. 29-46.
3. Survey, W.G.a.N.H., Rock Properties: Porosity and Density, in http://wisconsingeologicalsurvey.org/porosity_density/about_porosity_density.ht m, P. Sandstone, Editor 2010.
4. Ahmad, T., Reservoir Engineering Handbook. 2nd ed. 2000, Houston, Texas:
Butterworth-Heinemann. 1211.
5. Glover, P.W.J., Formation Evaluation. University of Aberdeen, UK: Department of Geology and Petroleum Geology.
6. Torsaeter, O., Abtahi, M., Experimental Reservoir Engineering Laboratory Work Book. 2000, Norway University of Science and Technology: Department of Petroleum Engineering and Applied Geophysics. 98.
7. Bradley, H., Petroleum Engineering Handbook. 1987.
8. Sandstone: Nugget. Available from: http://www.kocurekindustries.com/nugget- sandstone.
9. Ursin, J., Zolotukhin, A., B., Fundamentals of Petroleum Reservoir Engineering.
1997, Stavenger.
10. Unalmiser., S., Funk., J.,J., Engineering Core Analysis, in JPT1998, Saudi Aramco: Saudi Arabia.
11. Alme, K., Mylvaganam, S., Electrical Capacitance Tomography - Sensor Models, Design, Simulations, and Experimental Verification. IEEE Sensors Journal, 2006. 6(5): p. 1256-1266.
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12. Yang, W., Design of Electrical Capacitance Tomography Sensors. Measurement Science and Technology, 2010. 21: p. 1-14.
13. Yang, W.Q., Chondronasios, A., Natrass, S., Nguyen, V.T., Betting, M., Ismail, I., McCann, H., Adaptive calibration of capacitance tomography system for imaging water droplet distribution. Flow Measurement and Instrumentation, 2004. 15: p. 249-258.
14. Yang, W.Q., Modelling of capacitance tomography sensors. IEEE Proc.-Sci.
Meas. Technol., 1997. 144(5): p. 203-208.
15. Donthi, S., S., Capacitance based Tomography for Industrial Applications.
Electronic Systems Group, 2004.
16. Al-Aleef., A., S., Image Reconstructing in Electrical Capacitance Tomography of Manufacturing Processes Using Genetic Programming, in Graduate Studies2010, Al-Balqa Applied University: Al-Salt, Jordan. p. 151.
17. Gamio, J., C., Ortiz-Aleman, C., Martin, R., Electrical Capacitance Tomography Two-Phase Oil-Gas Pipe Flow Imaging by the Linear Back-Projection Algorithm. Geofisica International, 2005. 44(3): p. 265-273.
18. Rautenbach, C., Mudde, R.F., Yang, X., Melaaen, M.C., Halvorsen, B.M., A Comparative Study between Electrical Capacitance Tomography and Time- Resolved X-Ray Tomography, in Department of Process, Energy and Environment Technology2012, Telemark University College, Porsgrunn, Norway.
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APPENDICES
ACECT System Specification
1. Working environment
General Laboratory conditions
Temperature 0 ~ 50°C ambient
Humidity Without condensation
Power 110-240 V~
2. System hardware
Hardware units
Capacitance measurement board 8 2 measurement channels each board and 16 measurement channels in total
DDS signal generator board 1 Providing 2 programmable sinusoidal signals
Multiplexer 1 Compatible with Eurocase*
Backplane board 1 96 channels
PCI data acquisition board 1 With ADC, DAC and DI/DO
Ribbon cable 1 50 wires
Eurocase 1 19”
* Eurocase is a European standard for industrial and laboratory instrumentation
Hardware details
Number of measurement channel 2
Capacitance measuring circuit Sinusoidal excitation and phase-sensitive demodulation
Excitation frequency Programmable up to 500 kHz (Default frequency:
200 kHz)
Adaptive capacitance measurement range 0 ~ 2 pF (Different measurement range with different electrode pair/combination)
Capacitance resolution < 0.1 fF
Signal-to-noise ratio (SNR) > 60 dB
Power supply +5 V, ±15 V
Board format: Eurocard**
Connector to electrode SMB
Each capacitance measurement board
Connector to backplane board DIN41612 a/c-64 way plug
Number of generators 2
Signal type Sinusoidal
Signal frequency Programmable up to 500 kHz (Default frequency:
200 kHz)
Signal amplitude Programmable up to 20 Vp-p (Default amplitude: 16 Vp-p)
Phase between 2 sinusoidal signals 0 ~ 360° programmable
Power supply +5 V, ±15 V
Board format Eurocard
DDS signal generator board
Connector to backplane board DIN41612 a/c-64 way plug
Number of input channels 16
PGA gain 1, 2, 4, 8, 16
Power supply +5 V, ±15 V
Board format Eurocard
Multiplexer board
Connector to backplane board DIN41612 a/c-64 way plug
Board format Compatible with Eurocase
Backplane board
Connector DIN41612 a/c-64 way socket
Number of channels of analogue input 16
Resolution of ADC 12 bits
Number of analogue output 2
Resolution of DAC 12 bits
Number of DI/DO 24
Computer interface PCI
Data acquisition board
Data acquisition rate (without online display) >100 frames per second for a 12-electrode sensor
Input voltage range 85-264 V~
Input frequency 47 ~ 440 Hz
Outputs +5 V (3 A), +15 V (1.5 A) DC, -15 V DC (0.5 A)
Max. power 25 W
Power supply
CE marked Yes