Assessment of the stress path and prediction of fault activity in oil reservoirs(Ahvaz oil field)

Articles in Press

Document Type : Research Paper

Authors

1 Department of Earth Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Department of Petroleum Engineering, Omidiyeh Branch,Islamic Azad University, Omidiyeh, Iran.

Abstract

Understanding fault conditions and slip behavior is essential throughout the lifespan of a reservoir. The formation of new gaps or faults within a reservoir significantly increases the costs and risks associated with drilling operations. This research examined the potential for fracture formation resulting from discharge and a reduction in pore pressure. Well drilling data from a reservoir in southwest Iran were used to calculate the principal stresses and develop a geomechanical model. Based on this model, the safe mud weight window for drilling was also determined. Finally, the potential for fracture formation was assessed throughout the reservoir's production phase. The results show that the mud loss pressure in the reservoir corresponds to the minimum horizontal stress value (σ3), with an average value of approximately 41.75 MPa. The stress regime in the reservoir is a normal (σv> σH> σh), and the safest drilling direction is parallel to the vertical stress. According to the results, the orientations of the minimum and maximum horizontal stresses are N16W-S16E and N74E-S74W, respectively, with a standard deviation of 6.5 degrees. As a result of the production and discharge of hydrocarbon reservoirs, the initial pore pressure decreases. The decrease in pore pressure causes a change in the effective stress and subsequently the in situ stress field, and this phenomenon will cause new fractures and faults in the reservoir. The formation of new faults due to reservoir discharge is more likely to occur in the sandstone layers of the studied reservoir compared to the limestone and dolomite layers.

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Article Title [Persian]

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Geopersia

Articles in Press, Accepted Manuscript
Available Online from 10 March 2025

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History

  • Receive Date: 25 November 2024
  • Revise Date: 25 February 2025
  • Accept Date: 10 March 2025

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