Lithofacies variation of the Gachsaran Formation and its impact on the pressure regime in Abadan plain

Authors

Abstract

The Gachsaran Formation (Miocene in age) is the efficient cap rock for the Asmari reservoir in the Dezful embayment. Also, due to the plastic characteristic, it behaves as the upper detachment during Zagros folding. In addition, the recognition of specific pressure regime of this Formation is very important and vital in casing design and mud weight. In the current study, using the subsurface data from a number of 20 drilled wells covering Abadan Plain and contiguous area, the probable control of lithofacies on the pressure regime of the Gachsaran Formation was investigated. Hence, a number of stratigraphic correlation charts, isopach maps for the entire sequence of Gachsaran Fm. and members 4, 3 and 2 was provided. The correlation charts, show that the Gachsaran Formation consists of an alternation of marl, anhydrite with some minor carbonate interbeds, but without any salt beds in the crestal part of the Azadegan paleohigh in Abadan plain. Distancing from the crestal part of the paleohigh, toward the north and northeast, due to deepening of the depositional environment gradually salt interbeds appear, first in Member 4, then in Members 2 and 3. Integrating the lithofacies and operational data reveal the remarkable control of the lithofacies on the pressure regime of the Gachsaran Formation. Among the various mechanisms, the disequilibrium compaction can be considered as the cause for overpressuring, which amplified with the plastic behavior of salt interbeds.

Keywords

References

مطیعی، ه (1372) زمین شناسی ایران- چینه­شناسی زاگرس، سازمان زمین­شناسی کشور، 536 ص.
AbdollahieFard, I., Braathen, A., Mokhtari, M., and Alavi, S., A (2006) Interaction of the Zagros Fold–Thrust Belt and the Arabian-type, deep-seated folds in the Abadan Plain and the Dezful Embayment, SW Iran. Petroleum Geoscience, 12: 347–362.
Bahroudi, A., Koyi, H. A (2004) Tectono-sedimentary framework of the Gachsaran Formationin the Zagros foreland basin. Marine and Petroleum Geology, 21: 1295–1310.
James, G. A. and Wynd, J. G (1965) Stratigraphic nomenclature of Iranian oil consortium agreementarea. American Association of Petroleum Geologists Bulletin, 49(12): 2182–2245.
Osborne, M. J., and Swarbrick, R. E (1997) Mechanisms forgenerating overpressure in sedimentary basins: A reevaluation. AAPG Bulletin, v. 81, p. 1023–1041.
Pirouz, M., Simpson, G., Bahroudi, A.,  Azhdari, A (2011) Neogene sediments and modern depositional environments of the Zagros foreland basin system. Geol. Mag, 148 (5–6): 838–853.
Rezaee, P. and Salari, Sh (2016) Petrography and mineralogy of Gachsaran Formation in west of andar-Abbas, Kuh-e- Namaki Khamir section, south of Iran. Journal of Fundamental and Applied Sciences, 8(2S): 956-969.
Tucker, M. E ( 1991) Sedimentary petrology: an introduction to the origin of sedimentary rocks Oxford, Boston: Blackwell Scientific Publications, 260 p.
Hao, F., Li, S., Dong, W., Hu, Z., Huang, B (1998) Abnormal organic matter maturation in the Yinggehai Basin, South ChinaSea: Implications for hydrocarbon expulsion and fluid migration from overpressured systems. Journal of Petroleum Geology, 21( 4): 427–444.
Hao, F., Sun, Y., Li, S., Zhang, Q (1995) Overpressure retardation of organic-matter maturation and petroleum generation: a case study from the Yinggehai and Qiongdongnan Basins, South China Sea. AAPG Bulletin, 79 (4): 551–562.
Holmes, D. W (1978) Abnormal formation pressures and drilling problems in the agreement area. NIOC Report, TN-18/1978.
Hunt, J. M (1990) Generation and Migration of Petroleum from Abnormally Pressured Fluid Compartments (1). AAPG bulletin, 74(1): 1–12.
Hunt, J. M., Whelan, J. K., Eglinton, L. B., Cathles L. M (1994) Gas generation--A major cause of deep Gulf Coast overpressures. Oil and Gas Journal, 92: 29.
Japsen, P (1998) Regional velocity-depth anomalies, North Sea Chalk: a record of overpressure and Neogene uplift and erosion. AAPG Bulletin, 82(11): 2031–2074.
 Swarbrick, R. E., and Osborne, M. J (1998) Memoir 70, Chapter 2: Mechanisms that Generate Abnormal Pressures: an Overvie. AAPG Bulletin.
Tingay, M. R. P., Morley, C. K., Laird, A., Limpornpipat, O., Krisadasima, K., Pabchanda, S., Macintyre, Hamish, R ( 2013) Evidence for overpressure generation by kerogen-to-gas maturation in the northern Malay Basin. AAPG Bulletin, 4(4): 639–672.
Vejbæk, O. V (2008)  Disequilibrium compaction as the cause for Cretaceous – Paleogene overpressures in the Danish North Sea. AAPG Bulletin, 92(2): 165–180.
 

Files

History

  • Receive Date: 11 March 2020
  • Revise Date: 23 April 2020
  • Accept Date: 17 May 2020

Share

How to cite

Statistics