scholarly journals Facies Analysis and Depositional Stages of The Albian-Aptian Succession in Balad Oil Field, Central Iraq

2021 ◽  
Vol 54 (1B) ◽  
pp. 43-56
Author(s):  
Zainab Amer
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Facies Analysis ◽  
Depositional Environments ◽  
Oil Field ◽  
Delta Plain ◽  
Second Stage ◽  
The Third ◽  
Delta System ◽  
Distributary Channel

Carbonate-clastic succession which includes the Shu'aiba, Nahr Umr and Mauddud formations are representing a part of the Barremian-Aptian Sequence (Wasi'a Group). The present study includes three boreholes (Ba-1, 4 and 8) within the Balad Oil Field. The study area is located in central Iraq. This field represents a subsurface anticline with a northwest to southeast direction axis within the Mesopotamian Zone. Eight types of microfacies were recognized in the succession of the Mauddud and Shu’aiba formations. These microfacies represent shallow open marine, restricted and semi-restricted, reef - back reef, deep open marine and basinal depositional environments. While Nahr Umr Formation includes two successions, the first is the upper unit which is characterized by shale dominated rocks and the second is the lower unit which is characterized by sand-dominated rocks. Four major lithofacies were recognized in these two successions, they represent four depositional environments which are distributary channel, bay fill, delta plain and prodelta. The Albian-Aptian sequence was deposited during three cycles overlying the regional unconformity below the Shu’aiba Formation, the Zubair Formation, and ended with local unconformity with the Ahmadi Formation. The first stage is represented by deposition of Shu’aiba Formation during the sea-level rise after regression stage during the Zubair deposition which deposition in delta association facies. The second stage was showed a regressed of deposit the delta system above the shallow open marine of the Shu’aiba Formation, where the succession became characterized by mud-dominated rock with fissile and organic material. The third depositional stage is represented by the continuation of sea-level rise. This transgression leads to the building of carbonate ramp of the Mauddud Formation above the deltaic system of Nahr Umr Formation with a conformable surface. The Mauddud depositional stage was represented by two cycles of transgression succession, where appeared deepening upward in both cycles. The unconformity between these formations have been determined by observing the glauconite mineral and detected by log response in depth 2880m in well Ba-1.

scholarly journals Microfacies Analysis and Basin Development of Hartha Formation in East Baghdad Oil field, Central Iraq

2020 ◽  
pp. 2967-2978
Author(s):  
Bilal Jasim Homadi ◽  
Aiad Ali Hussien Al-Zaidy
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Planktonic Foraminifera ◽  
Depositional Environments ◽  
Oil Field ◽  
Microfacies Analysis ◽  
Second Stage ◽  
The Third ◽  
Third Stage ◽  
Marine Facies

The Hartha Formation is one of the important formations deposited during Late Campanian age. The present study deals with four boreholes (EB-53, 54, 55 and 56) within the East Baghdad oil field to diagnoses the microfacies and interpret the depositional environments. Six major microfacies were recognized in the succession of the Hartha Formation. Their characteristic grain types and depositional texture enabled the recognition of paleoenvironment. There are Orbitoides  wackestone-packstone , Orbitoides - miliolid wackestone, Peloidal and Pellets - echinoderm wackestone to packstone, Peloidal wackestone to packstone, Pelletal wackestone to packstone, and Planktonic foraminifera wackestone-packstone. Four associations’ facies were recognized in this succession, which are shallow open marine, deep open marine, semi-resricted, and restricted. The distribution of these associations led to the recognition of three major depositional stages in the studied succession. The first stage is represented by the semi-restricted facies within the lower part of the Hartha Formation, which is characterized by Orbitoides - miliolid wackestone to the northwest direction and developed to shallow open marine and deep marine to the southeast direction. In the second stage, the sea level was rising to deposit the deep open marine facies represented by planktonic foraminifera wackestone-packstone microfacies above the semi-restricted facies ,where the succession became characterized by Peloidal and Pellets - echinoderm wackestone to packstone microfacies of restricted association. The third stage is represented by the continuation of sea level rise. This caused the building of carbonate ramp of Shiranish Formation above the shallow open marine of Hartha Formation with conformable surface.

The physical sustainability of the coastal zone of the Ganges-Brahmaputra-Meghna delta under climatic and anthropogenic stresses

2021 ◽  
Author(s):  
Stephen Darby ◽  
Md. Munsur Rahman ◽  
Anisul Haque ◽  
Robert Nicholls ◽  
Frances Dunn
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Average Rate ◽  
River Management ◽  
Tidal River ◽  
Natural Conditions ◽  
Fluvial Sediment ◽  
Average Value ◽  
Delta Plain ◽  
The Ganges

<p>The Ganges-Brahmaputra-Meghna (GBM) delta is one of the world’s largest deltas, and consists of large areas of low flat lands formed by the deposition of sediment from the GBM rivers. However, recent estimates have projected between 200~1000 mm of climate-driven sea-level rise by the end of the 21st century, at an average rate of ~6 mm/yr. Eustatic sea-level rise is further compounded by  subsidence of the delta, which in the coastal fringes varies from 0.2 to 7.5 mm/yr, at an average value of ~2.0 mm/yr. Therefore, the combined effect of sea-level rise and subsidence (termed relative sea-level rise, RSLR) is around 8.0 mm/yr. Such high values of RSLR raise the question of whether sediment deposition on the surface of the delta is sufficient to maintain the delta surface above sea level. Moreover, as the total fluvial sediment influx to the GBM delta system is known to be decreasing, the retained portion of fluvial sediment on the delta surface is also likely decreasing, reducing the potential to offset RSLR. Within this context, the potential of various interventions geared at promoting greater retention of sediment on the delta surface is explored using numerical experiments under different flow-sediment regime and anthropogenic interventions.  We find that for the existing, highly managed, conditions, the retained portion of fluvial sediment on the delta surface varies between 22% and 50% during average (when about 20% of the total floodplain in the country is inundated) and extreme (> 60% of the total floodplain in the country is inundated) flood years, respectively. However, the degree to which sediment has the potential to be deposited on the delta surface increases by up to 10% when existing anthropogenic interventions such as polders that act as barriers to delta-plain sedimentation are removed. While dismantling existing interventions is not a politically realistic proposition, more quasi-natural conditions can be reestablished through local- sediment management using tidal river management, cross dams, dredging, bandal-like structures and/or combinations of the above measures.</p>

A Preliminary Study on Sedimentary Mode of Putaohua Oil Layer in the East of Sanzhao Depression

2012 ◽  
Vol 524-527 ◽  
pp. 3-9
Author(s):  
Lin Cong ◽  
Shi Zhong Ma ◽  
Yu Sun ◽  
Ru Bin Li
Keyword(s):  
Transition Region ◽  
Developmental Process ◽  
Sedimentary Facies ◽  
Oil Field ◽  
Sedimentary Characteristics ◽  
Sand Surface ◽  
Sand Body ◽  
Delta System ◽  
Preliminary Study ◽  
Distributary Channel

Based on ten well cores, seventeen hundred logging data and initial potential data, sedimentary characteristics and mode of shallow lacustrine fluvial-dominated delta of Putaohua oil layer in the east of Sanzhao depression were analyzed. It is realized that distributary channel sandbodies as sand body framework of this delta system, which is abundant, closely and narrow, and the framework of sand body is in a large number of narrow banded shape (mostly 200 ~ 300m), and can extend hundreds of kilometers of continuous, dense, overall was SW, and combines well with other types sand surface to become a better distributary channel sand body. Based on understanding of sedimentary background, developmental process, sedimentary characteristics and sedimentary facies type of Putaohua oil layer in Sanzhao depression, sedimentary mode of shallow lacustrine fluvial-dominated delta is established in the study area, and sedimentary mode of five subfacies is further divided: Delta distributary plain subfacies is mode of fluvial-dominated belt body; Transition region of front-distributary plain is mode of inshore; Inner front is mode of fluvial-dominated belt body; Transition region of inner front-outer front is mode of fluvial-dominated sheet sand; Shallow lacustrine fluvial-dominated delta outer front is mode of tide-dominated sheet sand; Also pointed out that overall shows NE –SW trending submerged distributary channel sandbodies which is abundant, closely and narrow is the main reservoir of the study area. It provides the solid geological basis for the establishment of spatial distribution pattern of reservoir; identify the causes of mainly monosandbody and further tapping the potential of oil field.

Transforming Fair Decision-Making About Sea-Level Rise in Cities: The Values and Beliefs of Residents in Botany Bay, Australia

2020 ◽  
Author(s):  
Anne Maree Kreller
Keyword(s):  
Decision Making ◽  
Sea Level Rise ◽  
Sea Level ◽  
Online Survey ◽  
Life Balance ◽  
The Third ◽  
Values And Beliefs ◽  
Interpretive Communities ◽  
Individual Consultation ◽  
Diverse Groups

Sea-level rise (SLR) is a threat to coastal areas and there is growing interest in how social values, risk perception and fairness can inform adaptation. This study applies these three concepts to an urban community at risk of SLR in Botany Bay, Australia. The study engaged diverse groups of residents via an online survey. Cluster analysis identified four interpretive communities: two groups value work–life balance, are concerned about SLR and would likely engage in collective adaptation. The third group value everything about Botany Bay and are active in organisations that could prove to be an important outreach. The fourth group were older men, disengaged from both SLR and policy but could respond to individual consultation and targeted communication. Thus, multifarious approaches can engage diverse communities in fair decision-making and transform community-facilitated adaptation.

Evolution of trilobite biofacies in Cambrian basins of the Siberian Platform

2000 ◽  
Vol 74 (6) ◽  
pp. 1000-1019 ◽  
Author(s):  
Tatyana V. Pegel
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Siberian Platform ◽  
Global Scale ◽  
Depositional Environments ◽  
Sign Reversal ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
Sea Level Fluctuations ◽  
Stratigraphic Succession

Cambrian biotic zonation on the Siberian Platform reflects differentiation of the depositional environments (inner shelf, outer shelf and open basin). The combination of the chart of trilobite biofacies replacement and the curve of sea-level fluctuations shows that trilobite biofacies replacement occurs as a rule at times of sign reversal and distinct change in the rates of sea-level rise or fall. The boundaries of major Siberian platform Cambrian chronostratigraphic units, such a stages and series, frequently coincide with the boundaries of biofacies in stratigraphic succession related to sea-level fluctuations. If these fluctuations are gradual and restricted, then the boundaries of the Cambrian stages and series cannot be isochronous levels at a global scale. The known levels for intercontinental correlation on the Siberian Platform include boundaries of the adjacent Triplagnostus gibbus and Tomagnostus fissus Zones from the uppermost Amganian Stage (Middle Cambrian) and the Glyptagnostus stolidotus and Glyptagnostus reticulatus Zones of the lower Upper Cambrian. Both levels correspond to boundaries between highstands and lowstands on the Siberian Platform and appear to serve as boundaries of high rank. Evolution of the trilobite biofacies zonation is illustrated by genera typical for each of the various Cambrian paleogeographic environments on the Siberian Platform.

Nass River on the move: radar facies analysis of glaciofluvial sedimentation and its response to sea-level change in northwestern British Columbia

2006 ◽  
Vol 43 (11) ◽  
pp. 1733-1746 ◽  
Author(s):  
S J McCuaig ◽  
M C Roberts
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Facies Analysis ◽  
Late Glacial ◽  
Depositional Environments ◽  
Coarse Grained ◽  
Sea Levels ◽  
Stratal Architecture ◽  
Forced Regression ◽  
Radar Facies

The Nass Valley of northwestern British Columbia is a glacial fiord containing extensive glaciomarine and glaciofluvial sediments. Two parallel braidplains, separated by a bedrock ridge, were deposited within the fiord. Mapping of these deposits led to the hypothesis that the braidplains must have terminated at deltas. However, a lack of surface exposures meant that ground-penetrating radar was needed to investigate these deposits. Radar facies analysis aided in the identification of braidplain, braid delta and glaciomarine depositional environments, as well as underlying bedrock. Several deltas graded to different sea levels were discovered, allowing inferences to be made about the relationship of falling sea level to sediment architecture. The upper section of the western braidplain is graded to a sea level of 185 m above sea level (asl), indicating that the proto-Nass River flowed on the western side of the bedrock ridge when the sea was at that level. However, the river moved to the east side of the ridge as sea level fell, depositing the extensive Aiyansh Braidplain – Braid Delta, which is graded to a 152 m sea-level stand. Several other deltas also formed at this sea-level stand. Avulsion occurred and the river flowed on the west side of the ridge again when sea level fell to 134 m asl. The river remained in this position throughout late glacial time and eventually evolved into the modern Nass River. The coarse-grained deposits are indicative of forced regression, with both stepped-top attached and detached stratal architecture present.

Multidecadal internal variability role in estimating sea level acceleration: Fremantle case study

2021 ◽  
Author(s):  
Armin Agha Karimi
Keyword(s):  
Pacific Ocean ◽  
Sea Level Rise ◽  
Sea Level ◽  
Low Frequency ◽  
Internal Variability ◽  
Anthropogenic Factors ◽  
Climate Indices ◽  
The Third ◽  
Trajectory Models

<p>Low frequency internal signals bring challenges to signify the role of anthropogenic factors in sea level rise and to attain a certain accuracy in trend and acceleration estimations; thus, modelling these signals is crucial. Due to both spatially and temporally poor coverage of the relevant data sets, identification of internal variability patterns is not straightforward. In this study, the identification and role of low frequency internal variability (decadal and multidecadal) in sea level change of Fremantle tide gauge station is analysed using two climate indices, Pacific Decadal Oscillation (PDO) and Tripole Interdecadal Pacific Oscillation (TPO). The wavelet transform is applied on the sea level and climate indices time series for this purpose. It is shown that the multidecadal sea level variability is anticorrelated with corresponding components of climate indices in the Pacific Ocean, with correlation coefficients of -0.9 and -0.76 for TPO and PDO, respectively. The correlations are comparatively low in decadal time scale, by correlation coefficient of approximately -0.5 for both indices. To estimate trend and acceleration in Fremantle, three trajectory models are tested. The first model is a simple second-degree polynomial comprising trend and acceleration terms. Low passed PDO, representing decadal and interdecadal variabilities in Pacific Ocean, is added to the first model to form the second model. For the third model, decomposed signals of decadal and multidecadal variability of TPO are added to the first model. For all trajectory models, different noise models are tried and according to Akaike and Bayesian information criteria, the best noise model is AR(5). In overall, TPO explains the low frequency internal variability better than PDO for sea level variation in Fremantle. Although the estimated trends does not change significantly for the three models, the estimated acceleration is substantially different. The accelerations estimated from the first and second models are statistically insignificant, 0.006 ± 0.012 mm.yr<sup>-2</sup> and 0.01 ± 0.01 mm.yr<sup>-2</sup> respectively, while this figure for the third model is 0.018 ± 0.01 mm.yr<sup>-2</sup>. The outcome exemplifies the importance of modelling low frequency internal variability in acceleration estimations for sea level rise in regional scale.</p>

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