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Overview of the methodology of cyclic division of wells of the south-western part of the Chardzhou step of the Bukhara-Khiva region based on industrial geophysics data
Обзор методики циклического расчленения разрезов скважин юго-западной части Чарджоуской ступени Бухаро-Хивинского региона, по данным промысловой геофизики
- National University of Uzbekistan, Uzbekistan
Highlights
- 15 wells on 15 areas of the Chardzhou step, each through at least 200 m of the Jurassic terrigenous formation.
- Kuyi Pamuk well 1: RCC-V 253 m, RCC-III 198 m, RCC-II 181 m; sandy interval at 3,451–3,471 m; RCC-IV resistivity 5–300 Ω·m.
- Berdikuduk well 1: RCC-V 277 m, RCC-IV 175 m.
- Urtabulak well 102: RCC-V 235 m, RCC-IV 219 m, RCC-III 111 m.
- RCC-II: Gurud; RCC-III: Degibadam; RCC-IV: Tangiduval; RCC-V: Baysun formation.
- Moving window, for example 4 m, with 50% or 75% overlap.
Keywords
- Jurassic
- well logging
- sedimentary cyclicity
- reservoir rocks
- stratigraphy
- Chardzhou step
- Bukhara–Khiva region
Summary
N. Abdullaev, D. Atabaev and Sh. Radjabov, of the National University of Uzbekistan, divide the Jurassic terrigenous section of the south-western Chardzhou step, Bukhara–Khiva region, into regional cycle complexes (RCC) by sedimentary cyclicity. Core and cuttings show coarse- and medium-grained sandstones, fine-grained clayey and calcareous sandstones, siltstones, thin interbeds of sandstone, siltstone and clay, clays and mudstones, and bituminous mudstones. The Jurassic terrigenous formation of the region and the south-western spurs of the Gissar consists of five formations: Kimirek, Gurud, Degibadam, Tangiduval and Baysun. Correlating it in wells is hard: the unified stratigraphic scheme rests on outcrops, core is scarce, and few wells cross the full thickness.
The authors digitised gamma-ray and laterolog logs and averaged them in a moving window, for example 4 m long, with 50% or 75% overlap, and traced the trends with depth. The analysis covers logs and core from 15 wells on 15 areas of the Chardzhou step, each through at least 200 m of the Jurassic terrigenous formation. Four complexes, RCC-II to RCC-V, were identified; RCC-I was not deposited in the area.
In Kuyi Pamuk well 1, RCC-V is 253 m thick, with a sharp drop in gamma-ray values, pointing to mainly sandy rock, at 3,451–3,471 m; in RCC-IV the laterolog resistivity varies from 5 to 300 Ω·m as porous sand beds alternate with less permeable silty clay; RCC-III, 198 m thick, has the highest resistivity and relatively good reservoir properties; RCC-II is 181 m thick. In Berdikuduk well 1, RCC-V is 277 m and RCC-IV, with signs of reservoir beds, 175 m. Urtabulak well 102, which crosses the full Jurassic terrigenous complex, has RCC-V of 235 m, RCC-IV of 219 m and RCC-III of 111 m. The authors match RCC-II to the Gurud, RCC-III to the Degibadam, RCC-IV to the Tangiduval and RCC-V to the Baysun formation.
How to cite
N. Abdullaev, D. Atabaev and Sh. Radjabov (2025). Overview of the methodology of cyclic division of wells of the south-western part of the Chardzhou step of the Bukhara-Khiva region based on industrial geophysics data. Seysmologiya muammolari (Problems of Seismology), vol. 7, No. 1, 2025, pp. 48–55. https://seismos.uz/uploads/pdf/journal/%D0%A1%D0%B5%D0%B9%D1%81%D0%BC%D0%BE%D0%BB%D0%BE%D0%B3%D0%B8%D1%8F%20%D0%BC%D1%83%D0%B0%D0%BC%D0%BC%D0%BE%D0%BB%D0%B0%D1%80%D0%B8%202025%20%E2%84%961.pdf