We are presenting at AAPG Europe Region Conference 2024 in Krakow

Petrostrat is excited to announce we will be attending and presenting at the upcoming AAPG Europe Regional Conference in Krakow, Poland, this summer. This event is hosted by the American Association of Petroleum Geologists (AAPG), co-hosted by IGS PAS (Institute of Geological Sciences, Polish Academy of Sciences) and Journal of the Polish Geological Society.

The focus of the conference is Europe’s approach to the Energy Transition, with dedicated sessions to foster exploring case studies and discussing rapidly emerging topics.

Hot topics will include;

• geology of the Carpathians and its foreland in Poland, as well as extending to include the East European Craton (including Ukrainian basins)
• geothermal energy utilization and storage (CCUS)
• geothermal energy utilisation
• hydrogen exploration and storage
• petroleum systems elements with a specific focus on salt tectonics, clastic and carbonate reservoirs and structural geology
• session devoted to thrust-fold belts in the European region (and beyond). Including the role of fault reactivation and inversion tectonics in fold belts

Everything you need to know about AAPG Europe Regional Conference 2024

John Cater, a Reservoir geologist at Petrostrat, will be presenting a talk titled “Combined Traps Within A Visean Fluvial-Deltaic System In The Kovalivsko-Sulymivska License Area As An Extension Of The Semyrenky Field, Dnipro-Donetsk Basin, Ukraine” outlining new research in collaboration with colleagues from Ukraine’s DTEK Oil&Gas.

Talk Title – Combined traps within a Visean fluvial-deltaic system in the Kovalivsko-Sulymivska license area as an extension of the Semyrenky Field, Dnipro-Donetsk Basin, Ukraine

Sergiy Yareshchenko¹, Yevgeniy Solodkyi¹, Suzi Burns², John Cater², and Mirko Looser²

¹DTEK Oil&Gas, ²PetroStrat

Talk Overview

1. Discovered in 1978, the Semyrenky Field comprises a relatively gentle anticline and numerous gas-condensate bearing sandstone reservoirs of Visean age, which were previously interpreted as shallow marine deposits with sheet-like geometry, based on the few cores available. Layer-cake stratigraphy is indicated at seismic (10-100m) scale.
2. Four main reservoirs (V-19v1, V-18v8, V-18v6 and V-17v1, traceable across the area on seismic) containing over 75% of reserves were penetrated at each well location. However, reservoir properties (thickness, porosity, homogeneity, etc.) vary from well to well, suggesting facies variation between wells rather than the same depositional environment.
3. At the later stages of the Semyrenky Field development, when most of the reservoirs were in production, it was noted that there are lateral barriers within even the most apparently extensive and continuous sands (as evident on seismic). Moreover, newly drilled wells showed the presence of multiple, isolated sand bodies mainly on the flanks of the Semyrenky anticline.
4. Exploration of the adjacent Kovalivsko-Sulymivska Field (KS Field) started much later in time, when over 20 wells had been drilled in the Semyrenky Field. Initial interpretation of the available 3D seismic indicated presence of three-way closure (a structural nose) in the southern part of the license, sealed by a fault interpreted to the east.
5. When a new wide azimuth 3D seismic survey was acquired over the Semyrenky and partially KS license, it became clear that there is no fault within the structural nose and, hence, no structural trap. An entrapment mechanism therefore required some stratigraphic element (lithology/facies change, erosion, etc.) to allow commercial hydrocarbon (HC) accumulation to be present.
6. In order to assess a proposed exploration well in the KS Field, available seismic was thoroughly interpreted, more core was cut and borehole images were recorded in the Semyrenky wells.
7. Seismic interpretation in the interval of V-19 – V-20 horizons suggested presence of a fluvio-deltaic system in the KS Field, prograding to the south-east.
8. New drilling and consecutive sedimentological studies on the Semyrenky field showed that the entire set of stacked reservoirs has a mainly shallow-water, fluvio-deltaic origin with minor, deeper water sands (hyperpycnites). Reservoir compartmentalization and the presence of isolated sand bodies was explained in this model and is compatible with earlier seismic interpretation of the delta in the KS Field. The Semyrenky reservoirs are formed by stacked fluvial channels, tidal influenced distributary channels, mouth bars, chute channels or their combinations, with few exceptions where sandstones originated from hyperpycnal gravity-flows.
9. The first exploration well drilled at the southern structural nose of the KS license area in 2021 discovered multiple hydrocarbon accumulations in V-17 to V-20 horizons. The well proved a combined trap formed by three-way closure and facies change (likely associated with clinoform development in the delta front).
10. Subsequent drilling of three additional wells in the KS Field allowed even better understanding of the entrapment mechanism and overall field complexity. Each well penetrated separate/isolated sand bodies and there is no communication between wells, which makes it very likely to have a high initial production rate in every next well, but also very difficult to predict the size of accumulation.