Three-Dimensional Modeling of Geo mechanical Units Using Seismic Data in One of the Southern Iran Gas Fields

Document Type : Research Paper

Authors

1 Faculty of Engineering, University of Tehran, Tehran, Iran

2 School of Geology, Faculty of Sciences, University of Tabriz, Iran

3 Pars Oil and Gas Company, Tehran, Iran

Abstract

The current study employs an efficient approach in construction of 3D reservoir geomechanical models based on the concept of GMUs. Rock strength estimation using indirect methods plays an important role in reservoir characterization. Indirect methods are more cost-effective and efficient than direct methods. The elastic-dynamic moduli can be used to obtain rock strength data. In this study, the amount of data was reduced through using multiresolution graph-based clustering and geomechanical units (GMUs) were established based on MRGC-derived clusters. Construction of a 3D geomechanical model using these GMU’s is a reliable approximation of reservoir characteristics from the rock strength point of view. The elastic-dynamic moduli such as Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio and UCS of the formation were calculated using compressive and shear wave velocities which are provided by DSI logging tools in eight wells. In some of the wells, shear wave velocities are predicted through multivariable regressions. Results show that the correlation coefficient between measured and estimated shear velocity is approximately 90 percent. Afterward, the calculated dynamic moduli were calibrated to static values using empirical equations extracted from a neighboring field. All calculated static moduli were clustered by using multiresolution graph-based clustering (MRGC) method for all eight wells. Finally, a 3D geomechanical model of the reservoir was generated based on these geomechanical units and the reservoir acoustic impedance model as a secondary parameter of co-krigging. The reservoir acoustic impedance model was built by using a genetic algorithm and model based inversion. After establishing the GMUs by MRGC, the GMUs evaluated through correlating with the caliper, gamma ray and NPHI logs. There is a good correlation between the clusters and the log-derived properties in all wells. GMUs can be compared with lithology logs and core data as an alternative verification method. Results of this study show that mechanical properties of GMUs are strongly affected by the clay content and porosity of rocks. Also, the 3D geomechanical model has been generated from GMUs, and the reservoir acoustic impedance model shows a good degree of correlation confirming further confidence on the results of this study.
 

Keywords

Main Subjects

References

[1]. Hussain M., El Hassan W. M. and Abdulraheem A., “Controls of grain-size distribution on geomechanical properties of reservoir rock-A case study: Cretaceous Khafji Member, Zuluf Field, Offshore Arabian Gulf,” Marine and Petroleum Geology., Vol. 23, pp. 703-713, 2006. ##
[2]. Zoback M. D., “Reservoir geomechnics,” Cambridge University Press, pp. 110-200, 2007. ##
[3]. Militzer, H. and Stoll R., “Einige Beitrageder geophysics zur primadatenerfassung im Bergbau: neue Bergbautechnik. Lipzig”, Vol. 3, pp. 21–25, 1973. ##
[4]. Aydin A., Basu A., “The Schmidt hammer in rock material characterization,” Engineering Geology, Vol. 81: pp 1–14, 2005. ##
[5]. Dusseault M. B., “Geomechanical challenges in petroleum reservoir exploitation,” KSCE J. Civ. Eng. Vol. 15 (4), pp. 669-678, 2011. ##
[6]. Castagna J. P., Batzle M. L. and Eastwood R. L., “Relationships between compressional wave and shear-wave velocities in clastic silicate rocks,” J. Geophys. Res. Vol. 50, pp. 571–581, 1985. ##
[7]. Method S. T., “Standard test method for laboratory determination of pulse velocities and ultrasonic elastic constants of rock,” Vol. 1, p. 14, 2000. ##
[8]. کدخدائی ع. گزارش تعیین سختی، "سرعت امواج اولتراسونیک و مقاومت فشاری تک محوری نمونه‌های سنگی یکی از چاه‌های نفتی جنوب ایران،" دانشگاه تربیت مدرس، 1392. ##
[9]. Mavko G., Mukerjii T. and Dorkin J., “Rock physics handbook,” Cambridge, United Kingdom (GBR), Cambridge University Press, 1998. ##
[10]. Brandestini A., “Proceq History,” http://www.proceq.com/en/company-partners/proceq-group/history.html?pqr=2, 30.2, 2015. ##
[11]. Ye S. J., and P. Rabiller., “A new tool for electro-facies analysis: multi-resolution graph-based clustering,” SPWLA 41st Annual Logging Symposium, 2000. ##
[12]. Kohonen T., “Self-organizing maps,” Third, extended edition, Springer, Vol. 501, 2001. ##
[13]. Lukasova A., “Hierarchical agglomerative clustering procedure,” Pattern Recognition, Vol. 1, pp. 365-381, 1979. ##
[14]. Schlumberger, Petrel Introduction course, “Schlumberger Information Solutions,” 2006. ##
[15]. Al-Ruwaili S., Chardac O., “3D model for rock strength and in-situ stresses in the Khuff formation of Ghawar field, methodologies and applications,” SPE 81476, The Middle East Oil Show & conference, Bahrain, 2003. ##
Journal of Petroleum Research
Volume 28, 1-97 - Serial Number 98
March and April 2018
Pages 85-96

Files

Share

How to cite

Statistics