NEW FOSSIL SITES IN DEPOSITS OF BASHKIRIAN STAGE (LOWER PENNSYLVANIAN) OF DONETS BASIN

AbstractA preliminary summary of the lower Visean to uppermost Moscovian (Carboniferous) conodont succession and biostratigraphy of the Dianzishang section in Zhenning, Guizhou, South China is presented. Eleven conodont zones, in ascending order, can be recognized:Gnathodus praebilineatus,Gnathodus bilineatus,Lochriea ziegleri,Declinognathodus noduliferus,Neognathodus symmetricus, ‘Streptognathodus’expansus(primitive form), ‘Streptognathodus’expansus,Mesogondolella donbassica – Mesogondolella clarki,Idiognathodus podolskensis,Swadelinafauna andIdiognathodus swadeizones. The first occurrences ofLochriea ziegleriat the base of the Serpukhovian Stage,Declinognathodus noduliferus noduliferusat the base of the Bashkirian Stage and ‘Streptognathodus’expansusat the base of the Moscovian Stage are recognized. The definitions of these stage boundaries, as well as that of the base of the Kasimovian Stage are discussed. Correlations with the Naqing section in South China, Russian and North American sections, as well as other important sections in the world, are considered.

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An Integrated Approach to Well Logging: The Case of the Bazhenov Formation

10.2118/208545-ms ◽

2021 ◽

Author(s):

Dmitry Mikhailovich Lazutkin ◽

Oleg Vladimirovich Bukov ◽

Denis Vagizovich Kashapov ◽

Albina Viktorovna Drobot ◽

Maria Alexandrovna Stepanova ◽

...

Keyword(s):

Gulf Of Mexico ◽

Integrated Approach ◽

Donets Basin ◽

Lower Carboniferous ◽

Upper Carboniferous ◽

Salt Domes ◽

Axial Part ◽

Gravity And Magnetic ◽

Play Elements ◽

Hydrocarbon Reserves

Abstract New geological structures – displaced blocks of salt diapirs’ overburden – were identified in the axial part of the Dnieper-Donets basin (DDB) beside one of the largest salt domes due to modern high-precision gravity and magnetic surveys and their joint 3D inversion with seismic and well log data. Superposition of gravity lineaments and wells penetrating Middle and Lower Carboniferous below Permian and Upper Carboniferous sediments in proximity to salt allowed to propose halokinetic model salt overburden displacement, assuming Upper Carboniferous reactivation. Analogy with rafts and carapaces of the Gulf of Mexico is considered in terms of magnitude of salt-induced deformations. Density of Carboniferous rocks within the displaced flaps evidence a high probability of hydrocarbon saturation. Possible traps include uplifted parts of the overturned flaps, abutting Upper Carboniferous reservoirs, and underlying Carboniferous sequence. Play elements are analyzed using analogues from the Dnieper-Donets basin and the Gulf of Mexico. Hydrocarbon reserves of the overturned flaps within the study area are estimated to exceed Q50 (Р50) = 150 million cubic meters of oil equivalent.

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Logging Optimization and Data Analysis Enabling Bypass Pay Identification and Hydrocarbon Quantification with Advanced Pulsed Neutron Behind Casing

10.2118/208512-ms ◽

2021 ◽

Author(s):

Sviatoslav Iuras ◽

Samira Ahmad ◽

Chiara Cavalleri ◽

Yernur Akashev

Keyword(s):

Cross Section ◽

Pore Space ◽

High Energy ◽

Elastic Cross Section ◽

Gas Production ◽

Donets Basin ◽

Lithology Identification ◽

Open Hole ◽

Pulsed Neutron

Abstract Ukraine ranks the third largest gas reserves in Europe. Gas production is carried out mainly from the Dnieper-Donets Basin (DDB). A gradual decline in reserves is forcing Ukraine to actively search for possible sources to increase reserves by finding bypassed gas intervals in existing wells or exploration of new prospects. This paper describes 3 case studies, where advanced pulsed neutron logging technology has shown exceptional value in gas-bearing layer identification in different scenarios. The logging technology was applied for formation evaluation. The technology is based on the neutron interaction with the minerals and the fluids contained in the pore space. The logging tool combines measurements from multiple detectors and spacing for self-compensated neutron cross-capture section (sigma) and hydrogen index (HI), and the Fast Neutron Cross Section (FNXS) high-energy neutron elastic cross section rock property. Comprehensive capture and inelastic elemental spectroscopy are simultaneously recorded and processed to describe the elemental composition and the matrix properties, reducing the uncertainties related to drilling cuttings analysis, and overall, the petrophysical evaluation combined with other log outputs. The proposed methodology was tested in several wells, both in open hole and behind casing. In the study we present its application in three wells from different fields of the DDB. The log data acquisition and analysis were performed across several sandstone beds and carbonates formation with low porosities (<10%), in various combinations of casing and holes sizes. The results showed the robustness and effectiveness of using the advanced pulsed neutron logging (PNL) technologies in multiple cases: Case Study A: Enabling a standalone cased hole evaluation and highlighting new potential reservoir zones otherwise overlooked due to absence of open hole logs. Case Study B: Finding by-passed hydrocarbon intervals that were missed from log analysis based on conventional open hole logs for current field operator. Case Study C: Identifying gas saturated reservoirs and providing solid lithology identification that previously was questioned from drilling cuttings in an unconventional reservoir.

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Overturned Salt Roof Flaps in the Dnieper-Donets Basin – Hiding a New Giant?

10.3997/2214-4609.202112683 ◽

2021 ◽

Author(s):

O. Petrovkyy ◽

T. Petrovska ◽

M. Firman ◽

A. Fedchenko ◽

O. Tsihovska ◽

...

Keyword(s):

Donets Basin

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Minimization of Negative Impact of Well Cementing on Productive Horizons by Utilization of Swellable Packers

10.2118/208510-ms ◽

2021 ◽

Author(s):

Mykhaylo Paduchak ◽

Viktor Dudzych ◽

Anatolii Boiko

Keyword(s):

Negative Impact ◽

Differential Pressure ◽

High Rate ◽

Donets Basin ◽

Technical Solution ◽

Negative Consequences ◽

Well Completion ◽

Stable Production ◽

Geological Conditions ◽

Gas Tight

Abstract Avoiding of negative impact of slurry contact with productive sections by utilization of swellable pakers well completion systems as a key solution for depleted reservoirs. Results are compared to previously used classic well completion method with production casing cementing The new method of the well completion is based on a long period and many wells operations within Svyrydivske field in Dnipro-Donets Basin (here and after DDB). Precise selection of hybrid, oil and water based elastomers and correct placement in the appropriate hole zones for water and sectional isolation together with oil based mud utilization during drilling have provided stable production in depleted reservoirs and have minimized negative consequences from water filtration. The results achieved and the well completion method are described in detail to allow readers to replicate all results in a comparable geological conditions in DDB. Current well completion method has a couple of outstanding results achieved: –well integrity barrier is based on sufficient differential pressure provided by swellable packers;–reliable long term water isolation of all detected water contained intervals;–the production sections are not polluted by slurry filtrated water;–increased production rate comparing to cemented wells;–no risks of slurry loss during well cementing. This technology has been successfully implemented in both vertical and deviated wells on 4.5″ (114.3 mm) casing OD, in the interval 5100-5450 meters, bottom hole temperature 120-135°C. The differential pressure provided by swellable packer is up to 10,000 PSI (68.9 MPa). Fluid reactive packers are ready to expand and isolate highly cavernous hole sections and keep differential pressure sustainably. To achieve the best results with this well completion method, it is also important to use reliable gas tight casing connections and know precise reservoir characteristics. That is why the technology is recommended to be customized for well known brownfield reservoirs with high rate of depletion. The main benefit of the well completion method is a proved and safe technical solution for mainly depleted deep gas and condensate deposits in DDB (Ukraine) with sensitive economics

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Modern Analogues of Sedimentation of Lower Permian Reservoirs in the Dnieper-Donets Depression

10.2118/208505-ms ◽

2021 ◽

Author(s):

Valentyn Loktyev ◽

Sanzhar Zharkeshov ◽

Oleg Gotsynets ◽

Oleksandr Davydenko ◽

Mikhailo Machuzhak ◽

...

Keyword(s):

Donets Basin ◽

Lower Permian ◽

River Channels ◽

Current Time ◽

Meandering Channels ◽

The North ◽

Complex Picture ◽

Middle Carboniferous ◽

The Indian Ocean ◽

Desert Dunes

Abstract The paper considers the problematics of identifying proper analogues for understanding carbonate and clastic reservoir distribution and prediction in the Lower Permian and Upper and Lower Carboniferous within the Dnieper-Donets basin. The focus of the exploration team was finding meandering rivers. This choice was proven good in mapping reservoirs and finding traps deeper in the Upper and Middle Carboniferous, although for Permian clastic section the approach was not helpful. The second option was desert dunes, but poor sorting of reservoirs suggests a more complex picture. Analogues such as desert environment is quite logical for describing Lower Permian as aridic climate, with red and brown shales and sands. Lower Permian reservoirs have a moon-like shape in the vertical sections that could be easily mistaken for river channels, but in such a dry climate, it is very likely water flow channels with sporadic hurricane-related activities. Core and logs shows chaotic grain sizes, but more with fine grains with almost no coarse grains. The source of sedimentary material could be mountains of Ukrainian Rock Shield from the South and Voronezh massif from the North. This conceptual model is proposing not to look for meandering channels, but more for braided channels with poorly sorted material. The current time analogue could be the Oman desert between the mountains and peninsula. From satellite images, braided channels are clearly visible in the direction towards the Indian Ocean. The channels’ internal structure is quite heterogeneous. This method suggests exploration targets with possible widths of the channels as big as hundreds of meters and their lengths under 10 and between 10-20 kilometres maximum.

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Factors controlling shale microstructure and porosity: A case study on upper Visean Rudov beds from the Ukrainian Dneiper–Donets Basin

AAPG Bulletin ◽

10.1306/05111817295 ◽

2018 ◽

Vol 102 (12) ◽

pp. 2629-2654 ◽

Cited By ~ 6

Author(s):

D. Misch ◽

J. Klaver ◽

D. Gross ◽

V. Mayer-Kiener ◽

F. Mendez-Martin ◽

...

Keyword(s):

Donets Basin

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