Regional study of controls on reservoir quality in the Triassic Skagerrak Formation of the Central North Sea

2017 ◽  
Vol 8 (1) ◽  
pp. 125-146 ◽  
Author(s):  
M. Akpokodje ◽  
A. Melvin ◽  
J. Churchill ◽  
S. Burns ◽  
J. Morris ◽  
...  
Keyword(s):  
North Sea ◽  
Clay Content ◽  
Reservoir Quality ◽  
Primary Control ◽  
Regional Study ◽  
Thin Sections ◽  
Porosity Evolution ◽  
Heterogeneous Reservoirs ◽  
Low Degree ◽  
Central North Sea

AbstractAn improved understanding of the controls on reservoir quality is key to ongoing and future exploration of the Central North Sea Triassic play. This paper presents a regional integrated study of 50 000 ft of wireline log data, 10 000 ft of core, 4431 routine core analyses measurements and 377 thin sections from 86 cored wells.Triassic Skagerrak Formation sandstones represent thin-bedded heterogeneous reservoirs deposited in a dryland fluvial–lacustrine setting. Fluvial-channel facies are typically fine–medium grained and characterized by a low clay content, whilst lake-margin terminal splay facies are finer grained, more argillaceous and micaceous. Lacustrine intervals are mud-dominated. Primary depositional textures retain a primary control on porosity evolution through burial. Optimal reservoir quality occurs in aerially and stratigraphically restricted fluvial-channel tracts on the Drake, Greater Marnock, Puffin and Gannet terraces, and the J-Ridge area. These primary textural and compositional controls are overprinted by mechanical compaction, the development of early overpressure and diagenesis. Anomalously high porosities are retained at depth in fluvial sandstones that have a low degree of compaction and cementation, including chlorite. Forward modelling of reservoir quality using Touchstone™ software has been validated using well UK 30/8-3 where reservoir depths are >16 000 ft TVDSS (true vertical depth subsea).

The Machar Field, Block 23/26a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 523-536 ◽  
Author(s):  
Zoë Sayer ◽  
Jonathan Edet ◽  
Rob Gooder ◽  
Alexandra Love
Keyword(s):  
North Sea ◽  
Debris Flows ◽  
Water Injection ◽  
Salt Diapir ◽  
Reservoir Quality ◽  
Complex Interplay ◽  
Light Oil ◽  
High Matrix ◽  
The Uk ◽  
Central North Sea

AbstractMachar is one of several diapir fields located in the Eastern Trough of the UK Central North Sea. It contains light oil in fractured Cretaceous–Danian chalk and Paleocene sandstones draped over and around a tall, steeply-dipping salt diapir that had expressed seafloor relief during chalk deposition. The reservoir geology represents a complex interplay of sedimentology and evolving structure, with slope-related redeposition of both the chalk and sandstone reservoirs affecting distribution and reservoir quality. The best reservoir quality occurs in resedimented chalk (debris flows) and high-density turbidite sandstones. Mapping and characterizing the different facies present has been key to reservoir understanding.The field has been developed by water injection, with conventional sweep in the sandstones and imbibition drive in the chalk. Although the chalk has high matrix microporosity, permeability is typically less than 2 mD, and fractures are essential for achieving high flow rates; test permeabilities can be up to 1500 mD. The next phase of development is blowdown, where water injection is stopped and the field allowed to depressurize. This commenced in February 2018.

Reservoir quality and rock properties modeling – Triassic and Jurassic sandstones, greater Shearwater area, UK Central North Sea

2015 ◽  
Vol 65 ◽  
pp. 1-21 ◽  
Author(s):  
Thomas R. Taylor ◽  
Mark G. Kittridge ◽  
Peter Winefield ◽  
L. Taras Bryndzia ◽  
Linda M. Bonnell
Keyword(s):  
North Sea ◽  
Rock Properties ◽  
Reservoir Quality ◽  
Central North Sea

Source and grain-size influences upon the clay mineral distribution in the Skagerrak and northern Kattegat

Clay Minerals ◽  
1998 ◽  
Vol 33 (1) ◽  
pp. 3-13 ◽  
Author(s):  
H. Bengtsson ◽  
R. L. Stevens
Keyword(s):  
Grain Size ◽  
Clay Mineral ◽  
North Sea ◽  
Clay Content ◽  
Sediment Provenance ◽  
Transport Pathways ◽  
Swedish West Coast ◽  
Mineral Distribution ◽  
Glacial Processes ◽  
Central North Sea

AbstractBottom sediments from 78 sites in the Skagerrak-Kattegat area have been used to determine the semi-quantitative distribution of clay minerals, and to interpret sediment provenance and the transport pathways. The sediment reflects incorporation of four sources, affected both by earlier glacial processes and on-going marine mixing. The southern North Sea, characterized by dioctaheadral illite, kaolinite and smectite, is the dominating source. The central North Sea provides a limited, but significant, source for chlorite. The sediment from the Swedish west coast has an unweathered character, containing trioctaheadral illite, vermiculite, illite-vermiculite mixed-layer minerals and chlorite. The contribution from the southern Kattegat (southern Sweden and Denmark) is dominated by kaolinite and smectite. Correlation between clay content and the contents of smectite, kaolinite and chlorite in the Skagerrak indicate that the clay mineral distribution is influenced by sorting. This grain-size dependency must be considered when interpreting sources.

scholarly journals Small-Scale Diagenetic Heterogeneity Effects on Reservoir Quality of Deep Sandstones: A Case Study from the Lower Jurassic Ahe Formation, Eastern Kuqa Depression

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-25
Author(s):  
LiKuan Zhang ◽  
Xiaorong Luo ◽  
Mingze Ye ◽  
Baoshou Zhang ◽  
Hongxing Wei ◽  
...  
Keyword(s):  
Effective Properties ◽  
Lower Jurassic ◽  
Coarse Grained ◽  
Small Scale ◽  
Reservoir Quality ◽  
Thin Sections ◽  
Kuqa Depression ◽  
Porosity Evolution ◽  
Reservoir Rocks ◽  
Porosity And Permeability

The Lower Jurassic Ahe Formation is an important exploration target for deep clastic reservoirs in the eastern Kuqa Depression. The Ahe Formation sandstones show heterogeneous porosity and permeability petrophysical properties. These properties have been poorly understood, limiting forecast of petroleum accumulations and making it difficult to develop the reservoirs. Based on cores, thin sections, SEM, and fluid inclusions, this study examined sandstone composition and texture and diagenetic heterogeneity at the core scale. The aim was to understand the influence of variations in detrital composition and texture on diagenetic and reservoir quality evolution. The Ahe Formation sandstones are dominantly fine- to coarse-grained litharenites, with minor feldspathic litharenites. In fining-up sand beds, detrital grain size determines the degree of mechanical compaction and, consequently, the abundance of porosity through ductile grains and muddy matrix. Local complete calcite cementation is a noticeable exception to this general trend. Three sandstone petrofacies have been defined based on texture and framework composition, detrital matrix, diagenesis, and pore types: (1) ductile-lean sandstone, (2) ductile-rich sandstone, and (3) tightly calcite-cemented sandstone. Different petrofacies experienced contrasting diagenetic and porosity evolution pathways. Ductile-lean sandstones underwent lower degree of compaction relative to ductile-rich sandstones during the eodiagenesis stage, and extensive grain dissolution occurred. The petrofacies remained relatively porous and permeable before early oil arrival. With continued burial, the porosity and permeability in the sandstones were further reduced by cementation. The petrofacies still had moderate porosity and permeability and were substantially charged when late petroleum migrated into the reservoirs. Thus, ductile-lean sandstones constitute effective reservoir rocks in deep reservoirs. By translating petrofacies to signatures of well logs, the effective properties of the reservoir rocks can be forecasted at the well scale.

The Maureen Field, Block 16/29a, UK Central North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 587-601 ◽  
Author(s):  
Peter M. Chandler ◽  
Barbara Dickinson
Keyword(s):  
North Sea ◽  
Upper Jurassic ◽  
Salt Dome ◽  
Reservoir Quality ◽  
Shelf Area ◽  
Clay Formation ◽  
Central North Sea

abstractThe Maureen field comprises the Maureen, Mary and Morag Accumulations, the reservoirs being Palaeocene Sandstones, Upper Jurassic sandstones and Permian dolomites respectively. The field lies about 10 km NNE of the Moira Palaeocene field. Maureen was discovered in 1973, came on-stream in 1983 and produced 217.4 MMBBL (from an estimated STOIIP of 397 MMBBL). The field ceased production in October 1999. It is trapped in a four-way dip closure over a salt dome and scaled by the overlying Lista Formation mudstones. The reservoir is up to 450 ft gross thickness, with core porosity from 18-28% and good sand connectivity. Morag was discovered in 1979. came on-stream in 1991 and produced 2.6 MMBBL before being shut-in in 1994. It produced from clean fractured dolomites in a stratigraphic trap. Mary was discovered and came on-stream in 1991. The initial well died after 1 year. A later well was put on-stream in 1997. Mary produced 2.83 MMBBL before final shut-in in June 1999. Reservoir quality is reasonable, but sand distribution is problematic. All the oils are sourced from the Kimmeridge Clay formation on the adjacent Maureen Shelf area.

Role played by clay content in controlling reservoir quality of submarine fan system, Forties Sandstone Member, Central Graben, North Sea

2021 ◽  
Vol 128 ◽  
pp. 105058
Author(s):  
Abdulwahab Muhammad Bello ◽  
Stuart Jones ◽  
Jon Gluyas ◽  
Sanem Acikalin ◽  
Matthieu Cartigny
Keyword(s):  
North Sea ◽  
Clay Content ◽  
Reservoir Quality ◽  
Submarine Fan
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