Sedimentological Analysis of Core Samples to Decipher Depositional Environments: A Case Study of ‘Valz-01’ Well Niger-Delta Basin, Nigeria

Current Journal of Applied Science and Technology ◽

10.9734/cjast/2019/v36i330237 ◽

2019 ◽

pp. 1-16

Author(s):

G. E. Maju-Oyovwikowhe ◽

F. A. Lucas

Keyword(s):

Marine Environment ◽

Niger Delta ◽

Depositional Environments ◽

Textural Characterization ◽

Beach Sediments ◽

Transitional Environment ◽

Niger Delta Basin ◽

Lithologic Unit

Sedimentological studies of ninety-seven feet (97ft) of core, covering 1643 -1797.74 m from ‘Valz-01’ well Offshore Eastern Niger Delta was carried out using twenty-four (24) core slabbed samples with the aim of identifying the textural characterization of sediments from the various sectors of the lithologic unit and to determine the environment of deposition. Six lithofacies units were identified within the cored interval. They include: Muddy heterolith, laminated fine sandstone/siltstone, Fine sandstone/siltstone, Hummocky fine sandstone/siltstone, laminated shale sandy, and shale. Three depositional environments identified include marine environment, transitional and continental environment. The marine environment is characterized by the deposits of shale (1644.27 - 1709) m, while the continental environment is characterized by sandstone (1779 - 1781) m. The transitional environment is characterized by alternation of siltstone and shale (1643 – 1644.22 and 1781 – 1797.74) m. From the studies most of the analyzed samples are deposited in the delta influenced by fluvial and waves actions revealing beach sediments and turbidites.

Download Full-text

Characterization of reservoir sands using 3D seismic attributes in the coastal swamp area of Niger Delta Basin

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01286-z ◽

2021 ◽

Author(s):

Oluwatoyin Khadijat Olaleye ◽

Pius Adekunle Enikanselu ◽

Michael Ayuk Ayuk

Keyword(s):

Seismic Data ◽

Niger Delta ◽

Seismic Attributes ◽

Effective Porosity ◽

High Porosity ◽

Hydrocarbon Accumulation ◽

3D Seismic ◽

Seismic Attribute ◽

Niger Delta Basin

AbstractHydrocarbon accumulation and production within the Niger Delta Basin are controlled by varieties of geologic features guided by the depositional environment and tectonic history across the basin. In this study, multiple seismic attribute transforms were applied to three-dimensional (3D) seismic data obtained from “Reigh” Field, Onshore Niger Delta to delineate and characterize geologic features capable of harboring hydrocarbon and identifying hydrocarbon productivity areas within the field. Two (2) sand units were delineated from borehole log data and their corresponding horizons were mapped on seismic data, using appropriate check-shot data of the boreholes. Petrophysical summary of the sand units revealed that the area is characterized by high sand/shale ratio, effective porosity ranged from 16 to 36% and hydrocarbon saturation between 72 and 92%. By extracting attribute maps of coherence, instantaneous frequency, instantaneous amplitude and RMS amplitude, characterization of the sand units in terms of reservoir geomorphological features, facies distribution and hydrocarbon potential was achieved. Seismic attribute results revealed (1) characteristic patterns of varying frequency and amplitude areas, (2) major control of hydrocarbon accumulation being structural, in terms of fault, (3) prospective stratigraphic pinch-out, lenticular thick hydrocarbon sand, mounded sand deposit and barrier bar deposit. Seismic Attributes analysis together with seismic structural interpretation revealed prospective structurally high zones with high sand percentage, moderate thickness and high porosity anomaly at the center of the field. The integration of different seismic attribute transforms and results from the study has improved our understanding of mapped sand units and enhanced the delineation of drillable locations which are not recognized on conventional seismic interpretations.

Download Full-text