Correction to: Lithology and fluid discrimination using rock physics-based modified upper Hashin–Shtrikman bound: an example from onshore Niger Delta Basin

Abstract Direct hydrocarbon indicator (DHI) expressions observed on seismic could arise due to various geological conditions. Such expression could lead to misinterpretation as hydrocarbon presence if not properly analyzed. This study employs rock physics attributes analysis to evaluate an identified prospect in the undrilled area of the studied reservoir. Prospect identification was actualized by analyzing structural and amplitude maps of the reservoir, which revealed a possible roll over anticline at both the exploited and prospective zone, with a very good amplitude support that conforms to structure. Well-based cross-plot analysis adopted four cross-plot techniques for feasibility study to test the applicability of rock physics for prospect evaluation in the field; Lambda-Rho versus Lambda-Rho/Mu-Rho ratio; Mu-Rho versus Lambda-Rho; and Poisson Ratio versus P-impedance. The result presented Poisson ratio, Lambda-Rho and Lambda/Mu-Rho ratio as good fluid indicator and Mu-Rho as a viable lithology indicator. As such, they were selected for seismic-based attribute and cross-plot analysis to validate the identified prospect. The results from seismic-based analysis showed consistency in the expression of the analyzed attribute at both the exploited and prospective zone. The seismic-based cross-plot analysis result was similar to the well-based analysis and was able to confirm that the observed amplitude expression in the exploited zone is an indication of hydrocarbon-bearing sand.

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Application of rock physics parameters for lithology and fluid prediction of ‘TN’ field of Niger Delta basin, Nigeria

Egyptian Journal of Petroleum ◽

10.1016/j.ejpe.2018.01.001 ◽

2018 ◽

Vol 27 (4) ◽

pp. 853-866 ◽

Cited By ~ 3

Author(s):

Chukwuemeka Patrick Abbey ◽

Emele Uduma Okpogo ◽

Ifeyinwa Obiageli Atueyi

Keyword(s):

Niger Delta ◽

Rock Physics ◽

Niger Delta Basin

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Hydrocarbon Prospectivity in the undrilled area of AIMA Field in the Niger Delta Basin, Nigeria.

Journal of Geoscience Engineering Environment and Technology ◽

10.25299/jgeet.2021.6.1.5431 ◽

2021 ◽

Vol 6 (1) ◽

pp. 34-41

Author(s):

Alexander Ogbamikhumi ◽

John Elvis Ighodalo

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Niger Delta ◽

Water Saturation ◽

Poisson Ratio ◽

Rock Physics ◽

Reservoir Properties ◽

Field Development ◽

Seismic Reservoir ◽

Niger Delta Basin

Field development is a very costly endeavor that requires drilling several wells in an attempt to understanding potential prospects. To help reduce the associated cost, this study integrates well and seismic based rock physics analysis with artificial neural network to evaluation identified prospects in the field. Results of structural and amplitude maps of three major reservoir levels revealed structural highs typical of roll over anticlines with amplitude expression that conforms to structure at the exploited zone where production is currently ongoing. Across the bounding fault to the prospective zones, only the D_2 reservoir possessed the desired amplitude expression, typical of hydrocarbon presence. To validate the observed amplitude expression at the prospective zone, well and seismic based rock physics analyses were performed. Results from the analysis presented Poisson ratio, Lambda-Rho and Lambda/Mu-Rho ratio as good fluid indicator while Mu-Rho was the preferred lithology indicator. These rock physics attributes were employed to validate the observed prospective direct hydrocarbon indicator expressions on seismic. Reservoir properties maps generated for porosity and water saturation prediction using Probability Neural Network gave values of 20-30% and 25-35% for water saturation and porosity respectively, indicating the presence of good quality hydrocarbon bearing reservoir at the prospective zone.

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Lithology and fluid discrimination using rock physics-based modified upper Hashin–Shtrikman bound: an example from onshore Niger Delta Basin

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-020-01073-2 ◽

2021 ◽

Vol 11 (2) ◽

pp. 569-578

Author(s):

C. G. Okeugo ◽

K. M. Onuoha ◽

A. C. Ekwe

Keyword(s):

Upper Bound ◽

Acoustic Impedance ◽

Niger Delta ◽

Rock Physics ◽

Time Lapse ◽

Successful Prediction ◽

Niger Delta Basin ◽

Reservoir Connectivity ◽

4D Seismic ◽

Gas Bearing

AbstractThe Ozifa reservoir is proven reservoir that cuts across the Northern and Greater Ughelli depo-belts of the Niger Delta Basin. This reservoir possesses heterogenous character southward of the field, making elastic properties, lithologies and fluid types difficult to describe accurately. In this study, rock physics template was applied to porosity and acoustic impedance (AI) crossplot clusters to illustrate rock–fluid relationships using modified Hashin–Shtrikman upper bound, Voigt upper bound and Reuss lower bound, as an input in the template. Values of acoustic impedance and porosity were used as lithofacies classification parameters for discrimination of lithofacies and fluid types. Our result showed that modified Hashin–Shtrikman upper bound line when applied in acoustic impedance (AI) and porosities (φ) crossplot domain discriminated gas-filled reservoirs from brine filled reservoirs and shale effectively. Similarly, results from crossplot showed clear separation of shale, heteroliths filled with brine and gas bearing sand, which was not plausible using conventional petrophysical analysis. This approach was successfully applied in analysing lithofacies and fluid relationship in different well locations and serves as a model for successful prediction of different lithology and fluid types, a major requirement for determining effects of geological variables such as sorting, clay distributions on the reservoir connectivity and optimum production using time-lapse (4D) seismic interpretation.

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Lithofacies Analysis and Qualitative Minerology of the Sediments of #3 Well in the Greater Ughelli Depobelt, Niger Delta Basin

Journal of Scientific Research ◽

10.3329/jsr.v13i2.49948 ◽

2021 ◽

Vol 13 (2) ◽

pp. 601-610

Author(s):

K. Itiowe ◽

R. Oghonyon ◽

B. K. Kurah

Keyword(s):

Physical Properties ◽

Clay Minerals ◽

Niger Delta ◽

Reservoir Quality ◽

X Ray Diffraction ◽

X Ray ◽

Sandy Shale ◽

Heterogeneous Nature ◽

Niger Delta Basin ◽

Shaly Sandstone

The sediment of #3 Well of the Greater Ughelli Depobelt are represented by sand and shale intercalation. In this study, lithofacies analysis and X-ray diffraction technique were used to characterize the sediments from the well. The lithofacies analysis was based on the physical properties of the sediments encountered from the ditch cuttings. Five lithofacies types of mainly sandstone, clayey sandstone, shaly sandstone, sandy shale and shale and 53 lithofacies zones were identified from 15 ft to 11295 ft. The result of the X-ray diffraction analysis identified that the following clay minerals – kaolinite, illite/muscovite, sepiolite, chlorite, calcite, dolomite; with kaolinite in greater percentage. The non-clay minerals include quartz, pyrite, anatase, gypsum, plagioclase, microcline, jarosite, barite and fluorite; with quartz having the highest percentage. Therefore, due to the high percentage of kaolinite in #3 well, the pore filing kaolinite may have more effect on the reservoir quality than illite/muscovite, chlorite and sepiolite. By considering the physical properties, homogenous and heterogeneous nature of the #3 Well, it would be concluded that #3 Well has some prospect for petroleum and gas exploration.

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Sedimentary facies and petrographic analyses of Miocene nearshore deposits, Central Swamp Depobelt, onshore Niger Delta Basin: implications for reservoir quality

Journal of Sedimentary Environments ◽

10.1007/s43217-021-00076-1 ◽

2021 ◽

Author(s):

Joseph Nanaoweikule Eradiri ◽

Ehimare Erhire Odafen ◽

Ikenna Christopher Okwara ◽

Ayonma Wilfred Mode ◽

Okwudiri Aloysius Anyiam ◽

...

Keyword(s):

Niger Delta ◽

Sedimentary Facies ◽

Reservoir Quality ◽

Petrographic Analyses ◽

Niger Delta Basin

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Evaluation of Reservoir’s Petrophysical Parameters, Niger Delta, Nigeria

International Journal of Advanced Geosciences ◽

10.14419/ijag.v5i1.7456 ◽

2017 ◽

Vol 5 (1) ◽

pp. 19

Author(s):

Ubong Essien ◽

Akaninyene Akankpo ◽

Okechukwu Agbasi

Keyword(s):

Niger Delta ◽

Gamma Ray ◽

Water Saturation ◽

Petrophysical Parameters ◽

Niger Delta Region ◽

Average Porosity ◽

Irreducible Water Saturation ◽

Open Hole ◽

Bulk Volume ◽

Niger Delta Basin

Petrophysical analysis was performed in two wells in the Niger Delta Region, Nigeria. This study is aimed at making available petrophysical data, basically water saturation calculation using cementation values of 2.0 for the reservoir formations of two wells in the Niger delta basin. A suite of geophysical open hole logs namely Gamma ray; Resistivity, Sonic, Caliper and Density were used to determine petrophysical parameters. The parameters determined are; volume of shale, porosity, water saturation, irreducible water saturation and bulk volume of water. The thickness of the reservoir varies between 127ft and 1620ft. Average porosity values vary between 0.061 and 0.600; generally decreasing with depth. The mean average computed values for the Petrophysical parameters for the reservoirs are: Bulk Volume of Water, 0.070 to 0.175; Apparent Water Resistivity, 0.239 to 7.969; Water Saturation, 0.229 to 0.749; Irreducible Water Saturation, 0.229 to 0.882 and Volume of Shale, 0.045 to 0.355. The findings will also enhance the proper characterization of the reservoir sands.

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