Delineating Depositional Environment through Lithostratigraphy and 2D Sequence Stratigraphy of a Typical Ramp Succession: In the Obom Field Niger Delta

2021 ◽  
Author(s):  
Onome Okobiebi ◽  
Becky Okobiebi
Keyword(s):  
Sequence Stratigraphy ◽  
Niger Delta ◽  
Depositional Environment ◽  
Facies Analysis ◽  
Seismic Analysis ◽  
3D Modelling ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
Depositional Patterns ◽  
Stacking Patterns

Abstract Modelling the most appropriate depositional environment is essential in the reservoir characterisation and 3D modelling of oil bearing sands and the integration of various workflows reduces the uncertainty in deciding the appropriate depositional model which serves as a precursor into petrophysical property distribution during 3D modelling. This paper elaborates a robust study of the integration facies analysis, 2D sequence Stratigraphy and biostratigraphy data in depicting the environment of deposition of the OBOM field. The lithological description of the G8 to the F5 reservoirs ranged from finning upward sequence and blocky shaped sequence as channel sands and coursing upward shoreface deposits. Mineralogical descriptions of the penetrated sands were also carried out, especially on the F5 reservoir in which the presence of radioactive minerals was decisive to constrain the depositional environment to lower shoreface. In the Sequence stratigraphic analysis two 3rd Order depositional cycles was identified from top to bottom in the field. This is substantiated by the facies trend, facies cross plot and cycles indicators like maximum flooding surfaces identified by regional marker shales, biofacies population and biodiversity charts and sequence stratigraphic methods like sequence thickness, bed stacking patterns and facies depositional patterns with regards sea level change. It was noticed that reservoir thickness reduces from the bottom to the top with the proximal channel sands in deep intervals gradually overlain by distal upper shoreface sands and lower shoreface sands at the shallower intervals. The gross depositional environment was a transgressive marine settings ranging from the lower shoreface and channelized upper shoreface deposits. The results from the integration of facies analysis, biofacies, seismic analysis and sequence stratigraphy results reduces uncertainty in depositional environment models.

scholarly journals Interpretation of Depositional Environment of Rho Field Using Sequence Stratigraphic Analysis, Shallow Offshore Depobelt, Niger Delta

2020 ◽  
pp. 93-103
Author(s):  
Okoli Emeka Austin ◽  
Acra Jones Edward ◽  
Ehirim Chukwuemeka Ngozi
Keyword(s):  
Niger Delta ◽  
Depositional Environment ◽  
High Energy ◽  
Delta Front ◽  
Fluvial Systems ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
Correct Orientation ◽  
Stacking Pattern ◽  
Input Reconstruction

Candidate Maximum Flooding Surfaces (MFS) identified on Rho-1, Rho-2 and Rho-3 were the basis of correlation across the wells for sequence Stratigraphic analysis in the field. Three (3) candidate MFS which include MFS-1, MFS-2 and MFS-3 were identified using the method adopted by Okoli [1]. Erosional surfaces were also delineated in wells from the observed stacking pattern between a sequence from Galloway model (1989) leading to the correlation of SB-1 and SB-2 across the wells. Using the Galloway model, four (4) depositional sequences were inferred SEQ (1-4). In the first sequence (SEQ 1), deposition occurred in a transgressive episode. Depositional environment was interpreted from electrofacies and revealing stacked sequences of reservoirs predominantly composed of fluvial channels which incised the Upper and Lower Shorefaces on a delta front system. In SEQ 2, looking at the aggradational pattern of the sequence, the formed channels were under the influence of both tidal and fluvial systems. In SEQ 3 and 4, based on electro-facies, the stacked reservoir sands were deposited predominantly in a shoreface/delta front environment and channel incisions in a wave subjugated high energy deltaic setting. The entire well section showed deposition in a regressive phase. Proposed conceptual models were generated using Petrel software and could be used as an input reconstruction of subsurface geological models. Indicating correct orientation of geo-bodies and facies belts (pinch outs of sands and shales), depositional dips and gross permeability architecture.

scholarly journals Facies Analysis and Depositoinal Environment of D-3 Reservoir Sands Vin Field, Eastern Niger Delta

2019 ◽  
pp. 1-19
Author(s):  
Onyewuchi, Chinedu Vin ◽  
Minapuye, I. Odigi
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Depositional Environment ◽  
Gamma Ray ◽  
Facies Analysis ◽  
Depositional Environments ◽  
Width Ratio ◽  
Neutron Density ◽  
Wireline Logs ◽  
Isopach Map

Facies analysis and depositional environment identification of the Vin field was evaluated through the integration and comparison of results from wireline logs, core analysis, seismic data, ditch cutting samples and petrophysical parameters. Well log suites from 22 wells comprising gamma ray, resistivity, neutron, density, seismic data, and ditch cutting samples were obtained and analyzed. Prediction of depositional environment was made through the usage of wireline log shapes of facies combined with result from cores and ditch cuttings sample description. The aims of this study were to identify the facies and depositional environments of the D-3 reservoir sand in the Vin field. Two sets of correlations were made on the E-W trend to validate the reservoir top and base while the isopach map was used to establish the reservoir continuity. Facies analysis was carried out to identify the various depositional environments. The result showed that the reservoir is an elongate , four way dip closed roll over anticline associated with an E-W trending growth fault and contains two structural high separated by a saddle. The offshore bar unit is an elongate sand body with length: width ratio of >3:1 and is aligned parallel to the coast-line. Analysis of the gamma ray logs indicated that four log facies were recognized in all the wells used for the study. These include: Funnel-shaped (coarsening upward sequences), bell-shaped or fining upward sequences, the bow shape and irregular shape. Based on these categories of facies, the depositional environments were interpreted as deltaic distributaries, regressive barrier bars, reworked offshore bars and shallow marine. Analysis of the wireline logs and their core/ditch cuttings description has led to the conclusion that the reservoir sandstones of the Agbada Formation in the Vin field of the eastern Niger Delta is predominantly marine deltaic sequence, strongly influenced by clastic output from the Niger Delta. Deposition occurred in a variety of littoral and neritic environment ranging from barrier sand complex to fully marine outer shelf mudstones.

A SEQUENCE STRATIGRAPHIC DEPOSITIONAL MODEL OF NEOPROTEROZOIC STRATA, YOWALGA AREA, OFFICER BASIN,WESTERN AUSTRALIA

2000 ◽  
Vol 40 (1) ◽  
pp. 15 ◽  
Author(s):  
S.N. Apak ◽  
H.T. Moors
Keyword(s):  
Seismic Data ◽  
Sequence Stratigraphic ◽  
Petroleum Systems ◽  
Stratigraphic Analysis ◽  
Regional Correlation ◽  
Depositional Settings ◽  
Potential Reservoir ◽  
Storm Wave ◽  
Flooding Events ◽  
Stacking Patterns

Additional data and further studies have now improved geological, geophysical, and geochemical understanding of the Neoproterozoic strata of the Officer Basin. New sequence stratigraphic analysis of continuously cored drillholes (particularly Empress–1/1A), extended throughout the area with wireline log and seismic correlations, provide enhanced recognition of depositional fades and thus basin architecture. Four major flooding events and fifteen sedimentary successions, interpreted as parasequence sets by regional correlation, are recognised across the Yowalga area. These parasequence sets are traceable using seismic data, with flooding events identified on cores and logs producing regional or local reflectors with good amplitude and continuity.Sedimen tary cycles are dominantly mixed carbonates- siliciclastics with primarily progradational stacking patterns. These imply transgressive and regressive cycles in a basin with low bathymetric relief. Depositional settings range from supratidal to just below storm wave base.This interpretation improves the prediction of potential petroleum systems. An architectural model for each formation allows prediction of depositional trends including potential reservoir, source rock and seal in the Yowalga area.

Integrating Wireline Logs and Seismic Data to Analyse The Facies snd Paleogeography of Tanjung Formation, Barito Basin, South Kalimantan

2020 ◽  
Author(s):  
E. A. Rosa
Keyword(s):  
Sequence Stratigraphy ◽  
Seismic Data ◽  
Depositional Environment ◽  
Well Logs ◽  
Facies Distribution ◽  
Sequence Stratigraphic ◽  
Core Data ◽  
Wireline Logs ◽  
Depositional Models

The study area is physiographically part of the Barito Basin, South Kalimantan (Van Bemmelen, 1949). 2D seismic data along with well logs from three wells, biostratigraphy data from two wells, and core data are utilized to do an integrated sequence stratigraphy. Petrography data from the equivalent formation at well-X from the study area is also used to support the evaluation. This study was to determine lithology facies and depositional environment based on several key maps: Sand Shale Ratio (SSR), Isopach, and Paleogeographic Maps. After that, seismically-supported sequence stratigraphy was applied to vertically and laterally subdivide the facies distribution and paleogeography into two depositional models based on the following key sequence-stratigraphic markers: (1) Sequence Boundary (SB)-1 to SB-2 that show regressive succession, and (2) SB-2 to Top Tanjung Formation that reflects transgressive phase.

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