Identification and Evaluation of Suitable Zones for Gas Production Using a One-Dimensional Geomechanical Earth Model in the Gas Shales of Western Iran

Document Type : Research Paper

Authors

Enhanced oil recovery research division, upstream oil field development and technology research center , research institute of petroleum industry , Tehran , Iran

Abstract

Due to their low permeability, unconventional resources such as gas shales require specialized production techniques like hydraulic fracturing and horizontal drilling. Effective design of these operations demands understanding rock fracturing mechanisms and integrating geomechanical parameters to identify optimal zones. In designing the geomechanical model of the gas shales, factors including natural fractures, mechanical properties of the layers, pore pressure, mineralogy, and in-situ stresses were considered. Using petrophysical data along with field and laboratory tests, a geomechanical model was created for each well. Results indicated that the pore pressure within the target layers was higher than normal, thus facilitating production. Furthermore, stress calculations indicated that the active stress regime in the region is strike-slip, and that the proximity of the minimum horizontal stress to the overburden pressure, coupled with significant difference between the minimum and maximum horizontal stresses, this condition led to numerous tensile and shear failures within the wellbore during drilling. Moreover, analysis of wellbore breakouts showed that the maximum horizontal stress has a northeast–southwest orientation. The depth intervals suitable for hydraulic fracturing in the studied wells were determined by evaluating two parameters: minimum horizontal stress and the brittleness index. The brittleness index, which reflects the rock’s tendency to form complex fractures under fluid injection, was calculated in situ using variations in Young’s modulus and Poisson’s ratio. On the other hand, the minimum horizontal stress plays a key role in restricting fracture propagation into adjacent layers. Accordingly, layers exhibiting lower minimum horizontal stress and higher brittleness index relative to their overlying and underlying formations were selected as optimal candidates for hydraulic fracturing.

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References

[1]. IEA, Golden Rules for a Golden Age of Gas. 2013, International Energy Agency (IEA): Paris.
[2]. Li, X. J., Lu, Z. G., Dong, D. Z., & Cheng, K. (2009). Geologic controls on accumulation of shale gas in North America. Natural Gas Industry, 29(5), 27-32.##
[3]. Adekola, U.A., Gimba, A.S., Ayuba, S., JakadaI, K., Okafor, I., Nzerem, P., Chior, J., Ogolo, O. and Ibrahim, K.S., (2023). A comprehensive review of hydraulic fracturing techniques in shale gas production. Nile Journal of Engineering and Applied Science, 1(1), 216-228. ##
[4]. Shan, Q., Jin, Y., Tan, P., & Zhang, R. (2018). Experimental and numerical investigations on the vertical propagation of hydraulic fractures in laminated shales. Journal of Geophysics and Engineering, 15(4), 1729-1742. doi.org/10.1088/1742-2140/aac12f. ##
[5]. Karagianni, A., Karoutzos, G., Ktena, S., Vagenas, N., Vlachopoulos, I., Sabatakakis, N., & Koukis, G. (2010). Elastic properties of rocks. Bulletin of the Geological Society of Greece, 43(3), 1165-1168. doi.org/10.12681/bgsg.11291. ##
[6]. Mostyn, G., & Douglas, K. (2000, November). Strength of intact rock and rock masses. In ISRM International Symposium (pp. ISRM-IS). ISRM. ##
[7]. Malkowski, P., & Ostrowski, L. (2017, June). The methodology for the Young modulus derivation for rocks and its value. In ISRM EUROCK (pp. ISRM-EUROCK). ISRM. ##
[8]. Ji, S., Li, L., Motra, H. B., Wuttke, F., Sun, S., Michibayashi, K., & Salisbury, M. H. (2018). Poisson’s ratio and auxetic properties of natural rocks. Journal of Geophysical Research: Solid Earth, 123(2), 1161-1185. doi.org/10.1002/2017JB014606. ##
[9]. Lakirouhani, A., & Jolfaei, S. (2023, December). Conflict Between Fracture Toughness and Tensile Strength in Determining Fracture Strength of Rock Samples with a Circular Hole. In International Conference on CivilEngineering (pp. 495-503). Singapore: Springer Nature Singapore. ##
[10]. King, G. R. (1993). Material-balance techniques for coal-seam and devonian shale gas reservoirs with limited water influx. SPE reservoir engineering, 8(01), 67-72. doi.org/10.2118/20730-PA. ##
[11]. Riyahi, A. M. A., & Bagheri, M. (2018). Estimation of pore pressure using Eaton and Bowers methods with seismic and well logging data. Applied Geophysics Research, 4(2), 267–275. (in Persian). ##
[12]. Eaton, B. A. (1975, September). The equation for geopressure prediction from well logs. In SPE Annual Technical Conference and Exhibition? (pp. SPE-5544). SPE. doi.org/10.2118/5544-MS. ##
[13]. Fooladchi, S., Farouq Hosseini, M. & Ganji, M. (2006). Laboratory study of the effect of sample geometry on dynamic and static elastic properties of Neka limestone. Journal of Mining Engineering, 1(1), 1–10. (in Persian). ##
[14] Zarei, V. & Davoodi Jajarm, A. (2009). Relationship between static and dynamic parameters of dolomitic limestone to calcareous dolomite at the site of the Rudbar Dam, Lorestan. 3rd Iranian Mining Engineering Conference, Yazd. (in Persian). ##
[15]. Zoback, M.D., Barton, C.A., Brudy, M., Castillo, D.A., Finkbeiner, T., Grollimund, B.R., Moos, D.B., Peska, P., Ward, C.D. and Wiprut, D.J. (2003). Determination of stress orientation and magnitude in deep wells. International Journal of Rock Mechanics and Mining Sciences, 40(7-8), 1049-1076. doi.org/10.1016/j.ijrmms.2003.07.001. ##
[16]. He, J. H. (2006). Some asymptotic methods for strongly nonlinear equations. International Journal of Modern physics B, 20(10), 1141-1199. (in Persian). ##
[17]. Zoback, M. D. (2010). Reservoir geomechanics. Cambridge university press. ##
[18]. Molaghab, A., Taherynia, M. H., Fatemi Aghda, S. M., & Fahimifar, A. (2017). Determination of minimum and maximum stress profiles using wellbore failure evidences: a case study—a deep oil well in the southwest of Iran. Journal of Petroleum Exploration and Production Technology, 7(3), 707-715. ##
[19]. Yang, Y., Shi, X., Ji, C., Yan, Y., An, N., & Zhang, T. (2024). The hydraulic fracturing optimization for stacked tight gas reservoirs using multilayers and multiwells fracturing strategies. Energy Engineering, 121(12). ##
[20]. Zhao, Z., Wu, T., Liang, H., Guo, J., & Zhou, X. (2024). Fracturability of shale based on rock brittleness and natural fracture tensile reactivation. Petroleum Geoscience, 30(4), petgeo2023-119. doi.org/10.1144/petgeo2023-119. ##
[21]. Hadei, M. R., & Veiskarami, A. (2021). An experimental investigation of hydraulic fracturing of stratified rocks. Bulletin of Engineering Geology and the Environment, 80(1), 491-506. ##
[22]. Jin, X., Shah, S. N., Roegiers, J. C., & Zhang, B. (2014, February). Fracability evaluation in shale reservoirs-an integrated petrophysics and geomechanics approach. In SPE hydraulic fracturing technology conference and exhibition (pp. SPE-168589). SPE. doi.org/10.2118/168589-MS. ##
[23]. Abdelaal, A., Aljawad, M. S., Alyousef, Z., & Almajid, M. M. (2021). A review of foam-based fracturing fluids applications: From lab studies to field implementations. Journal of Natural Gas Science and Engineering, 95, 104236. doi.org/10.1016/j.jngse.2021.104236. ##
[24]. Passey, Q. R., Bohacs, K. M., Esch, W. L., Klimentidis, R., & Sinha, S. (2010, June). From oil-prone source rock to gas-producing shale reservoir–geologic and petrophysical characterization of unconventional shale-gas reservoirs. In SPE International Oil and Gas Conference and Exhibition in China (pp. SPE-131350). SPE. doi.org/10.2118/131350-MS. ##
[25]. Chang, C., Zoback, M. D., & Khaksar, A. (2006). Empirical relations between rock strength and physical properties in sedimentary rocks. Journal of Petroleum Science and Engineering, 51(3-4), 223-237. doi.org/10.1016/j.petrol.2006.01.003. ##
Journal of Petroleum Research
Volume 35, 1404-5 - Serial Number 144
January and February 2025
Pages 41-59

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