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Petrophysical Evaluation of Cretaceous System Sediments in Amu Darya Basin
- Department of Petroleum, Mining and Environmental Engineering Faculty, Balkh University, Mazar-e-Sharif, Afghanistan
- Department of Geology and Mine, Engineering Faculty, Badakhshan University, Faizabad, Afghanistan
https://doi.org/10.68837/bjns.v1i2.39
Highlights
- Triassic sandstones and siltstones: porosity up to 4%.
- Lower–Middle Jurassic sandstones (Khwaja Bolan, Khwaja Gugerdak, Boinghor): about 3,000 m in all; porosity 11–12%, permeability up to 200 mD.
- Upper Jurassic limestone, Khwaja Gugerdak: gas flow of 1.3 million m³ a day.
- Hauterivian (Getrif) sandstones: open porosity 14.4% on average, effective about 8%; permeability mostly 100–600 mD, 603 mD (Alborz) and 706 mD (Shiram block); effective thickness up to 100 m (Sheberghan, Boinghor), 60 m (Alborz, Shiram, Andkhoy), 25 m (Jangal Kalan).
- Barremian seal: about 40 m, up to 100 m of dense anhydritic clays.
- Lower Albian sandstones: porosity about 15%, permeability about 2 mD. Angut: oil flow of more than 30 t a day from the Albian, which is about 240 m thick there.
Keywords
- Amu Darya
- Cretaceous
- Geochemistry Hydrocarbon
- Petrophysics
Summary
W. A. Fooshanji of Balkh University and A. R. Bahrampoor of Badakhshan University review the petrophysical properties of the Cretaceous rocks of the Amu Darya basin in northern Afghanistan, together with the Triassic and Jurassic rocks beneath them. Their data come from drilling reports, cores, flow tests and well logs in the Khwaja Gugerdak, Yatim Taq, Angut, Qashqari, Aq Darya, Andkhoy and Jangal Kalan areas.
The Triassic rocks, mostly sandstones and siltstones, are thick but have porosity of up to 4% and no petroleum system of their own. Lower–Middle Jurassic sandstones, about 3,000 m thick in all in the Khwaja Bolan, Khwaja Gugerdak and Boinghor wells, have porosity of 11–12% and permeability of up to 200 mD. The Upper Jurassic carbonates, limestone below and dolomite above, are productive at Khwaja Gugerdak and Yatim Taq. Tests of the upper limestone gave gas at 1.3 million m³ a day at Khwaja Gugerdak, and the lower limestone a little water; in the dolomite, Yatim Taq well 5 gave gas and Andkhoy well 2 a gush of water.
In the Lower Cretaceous, the Berriasian–Valanginian Karabil suite of sandstones, carbonates, shales and siltstones is a source rock in places. Together with the Valanginian part of the Al-Morad suite it has permeability of about 3 mD and porosity of about 10–15%, so it is almost no reservoir. The Valanginian rocks lie unconformably on the Jurassic in the Qashqari, Angut and Aq Darya blocks and are 90–106 m thick there. The Hauterivian (Getrif) sandstones are the main productive layer: open porosity averages 14.4% and effective porosity about 8%, and permeability in the lower sandstones is mostly 100–600 mD, reaching 603 mD in the Alborz structure and 706 mD in the Shiram block, while in Jangal Kalan well 3 most of them are impermeable. In the Khulm section their porosity is 8–15%. Their effective thickness reaches 100 m around Sheberghan and in the Boinghor structure, 60 m in the Alborz structure, the Shiram block and Andkhoy, and 25 m at Jangal Kalan.
The Barremian layer, about 40 m and up to 100 m of dense anhydritic clays, is a good seal, with 10–15 m beds of limestone and dolomite that are productive in places. Aptian sandstones, 8–27 m thick at Khwaja Bolan, 12–20 m at points 5 and 7 of Khwaja Gugerdak, 6 m at Andkhoy and absent at Jangal Kalan, have average reservoir properties. Lower Albian sandstones have porosity of about 15% but permeability of only about 2 mD. The middle Albian layers gave short-lived flows at Yatim Taq, Khwaja Bolan and Jangal Kalan, and at Angut an oil flow of more than 30 tonnes a day that later stopped; the Albian is about 240 m thick at Angut. The Upper Cretaceous–Paleogene Ghori suite of clays, marls, dolomite and anhydrite is up to 300 m thick at Angut and up to 500 m at Qashqari.
The authors conclude that the Cretaceous rocks of the Afghan part of the basin are thinner than in the countries to the north but have good saturation and thermal maturity. They recommend denser sampling, more laboratory work and 2D and 3D modelling, especially at Jangal Kalan and Andkhoy. The basin as a whole is described in Ulmishek (2004) and Schenk et al. (2026).
How to cite
W. A. Fooshanji and A. R. Bahrampoor (2026). Petrophysical Evaluation of Cretaceous System Sediments in Amu Darya Basin. Balkh International Journal of Natural Science, 1(2), 103–125. https://doi.org/10.68837/bjns.v1i2.39