Complete Loss, Blowout and Explosion of Shallow Gas, Infelicitous Horoscope in Middle East

Nabaei, M.; Moazzeni, Ali Reza; Ashena, Rahman; Roohi, Abbas

doi:10.2118/139948-ms

Cited by 6 publications

(1 citation statement)

References 9 publications

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“…From the surface to a 7 km depth, three abnormally pressured formations are present in the Dezful Embayment: the Miocene evaporitic Gachsaran Formation (Lower Fars), the Triassic Dashtak Formation, and the Lower Cretaceous carbonate Fahliyan Formation. Almost all wells drilled in the Embayment experience difficulties in penetrating the Gachsaran Formation, sometimes leading to blowouts [54]. The pressure gradient in the Gachsaran Formation ranges from 15.5 to 22.1 MPa/km in several oil fields located in the Dezful Embayment, such as the Masjid-i-Sulaiman, Lali, Haft-Kel, Naft Safid, Agha-Jari, Pazanan, Gachsaran, and Naft Shahar.…”

Section: Stress Magnitudementioning

confidence: 99%

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

et al. 2021

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This study focuses on determining the orientation and constraining the magnitude of present-day stresses in the Dezful Embayment in Iran’s Zagros Fold and Thrust Belt. Two datasets are used: the first includes petrophysical data from 25 wells (3 to 4 km deep), and the second contains 108 earthquake focal mechanisms, mostly occurring in blind active basement faults (5 to 20 km deep). Formal stress inversion analysis of the focal mechanisms demonstrates that there is currently a compressional stress state ( in the basement. The seismologically determined SHmax direction is 37° ± 10°, nearly perpendicular to the strike of most faults in the region. However, borehole geomechanics analysis using rock strength and drilling evidence leads to the counterintuitive result that the shallow state of stress is a normal/strike-slip regime. These results are consistent with the low seismicity level in the sedimentary cover in the Dezful Embayment, and may be evidence of stress decoupling due to the existence of salt layers. The stress state situation in the field was used to identify the optimally oriented fault planes and the fault friction coefficient. This finding also aligns with the prediction Coulomb faulting theory in that the N-S strike-slip basement Kazerun Fault System has an unfavorable orientation for slip in a reverse fault regime with an average SW-NE SHmax orientation. These results are useful for determining the origin of seismic activity in the basin and better assessing fault-associated seismic hazards in the area.

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Section: Stress Magnitudementioning

confidence: 99%

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

et al. 2021

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Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

Yaghoubi

Mahbaz

Dusseault

et al. 2020

Preprint

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Statistical analysis of past kicks and blowouts occurred in a Middle Eastern oilfield

Ashena

Bahreini²,

Lotfi³

2023

J Petrol Explor Prod Technol

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In 2017, blowouts and then explosions occurred in a Middle Eastern oilfield. A root cause of the incident is lack of study and investigation of the past kicks and blowouts data. Therefore, as a pioneer work in the region, data gathering and analysis of past kicks and blowouts were made in the studied oilfield to learn lessons and find gaps. Out of the 149 drilled wells, a total of 117 kicks and three (3) blowouts occurred. In this work, a list of drilling parameters to be considered in data gathering and analysis were suggested as a guideline for future works elsewhere. The statistical analysis not only showed all the three exploration wells kicked which is not a surprise, but it also showed that 39 out of 146 (26.71%) also experienced kicks during reservoir drilling. The large number of kicks in development wells proved that possibility of kick occurrence in development wells is not low. In exploration wells, the predominant kick causes were gas-cut mud and insufficient mud weight which indicates the necessity of using pressure while drilling in addition to drilling rate control systems in exploration wells. However, in development wells, lost circulation was the predominant kick cause indicating the necessity of using low-weight drilling fluids and managed pressure drilling systems. The direct role of human error exists at least in 60% of kicks occurred in this field, which shows the great importance of improved drilling personnel training. Although only 3.45% kicks in development wells occurred due to improper hole fill-up during tripping, this cause should not only be deemed trivial, but it should also be taken seriously as being the cause of the blowout. The 2.56% possibility of kick conversion to blowouts and 67% risk of blowout conversion to explosion emphasize the necessity of maintaining primary well control and using efficient and early kick detection systems. Bullhead was the more commonly used method than standard well control methods; as this kill method may not always be safe, its application should be revised.

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Complete Loss, Blowout and Explosion of Shallow Gas, Infelicitous Horoscope in Middle East

Cited by 6 publications

References 9 publications

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

Statistical analysis of past kicks and blowouts occurred in a Middle Eastern oilfield

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