Lithology and fluid prediction from simultaneous seismic inversion over Sandfish field, Niger Delta, Nigeria

Adeoti, Lukumon; Adesanya, Oluwakemi Y.; Oyedele, K. F.; Afinotan, Itsemode P.; Adekanle, a.

doi:10.1007/s12303-017-0018-4

Cited by 13 publications

(14 citation statements)

References 10 publications

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“…The plot towards the second quadrant as captured by the ash box (Fig. 11a) deviates from the background trend and therefore is classified as class IV AVO response (after Castagna et al, 1998;Adeoti et al, 2017). Figure 11b, the cross-plot of Gradient against intercept for 'Sand e' does not show any significant deviation from background trend compared to Figure 11a.…”

Section: Synthetic Seismogrammentioning

confidence: 93%

“…Seismic reflection method has been effective in such challenging areas in detecting structures capable of trapping hydrocarbon but among the various seismic technique for hydrocarbon detection and monitoring in the subsurface, the Amplitude Variation with Offset (AVO) analysis appears to be quite promising with pore fluid identification. Only AVO analysis, which requires special handling of the data, can distinguish lithology changes from fluid changes (Castagna, 1993;Chiburis et al, 1993;Adekanle and Enikanselu, 2013;Adeoti et al, 2017). Almost all major companies use AVO routinely as a tool to "de-risk" exploration targets and to better define the extent and the composition of existing hydrocarbon reservoirs (Omudu and Ebeniro, 2005;Castagna and Chopra, 2007;Adeoti et al, 2014;Schlumberger, 2014).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the effectiveness of using quantitative avo analysis in fluid and lithology discrimination in an offshore Niger Delta Field, Nigeria

Adeoti¹,

Ikoro²,

Adesanya³

et al. 2018

Ife Journal of Science

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Quantitative Amplitude Variation with Offset (AVO) analysis of "Jay" Field, offshore Niger Delta, was carried out with a view to properly discriminating fluid and lithology using near, mid and far offset seismic and well data. Seismic and well data were interpreted and analyzed. Synthetic seismogram was generated using density (r) and sonic logs. AVO modeling, seismic AVO attribute analysis and AVO inversion were carried out and the results from well log interpretation using 70-API gamma-ray cutoff , neutron-density over lay and resistivity logs revealed that the field consists of intercalation of sand and shale with typical deltaic depositional environment log signatures. Four identified sand reservoirs (a, b, c and d) with high resistivity values and negative separation in the neutron-density overlay suggested that the field was hydrocarbon bearing probably containing gas or condensate. Two sand reservoirs showed good rock physics results, 'Sand a' at 11,632 ft TVD with 18% porosity (ϕ), 0.25 water saturation (S), decreasing ratio of compressional wave velocity to shear wave velocity (V /V) w p S and Poisson's ratio () relative to the background shale signified AVO response typical of a hydrocarbon bearing sand. 'Sand e' at 5,925 ft TVD, with 30% ϕ, Sw of 1, no change in V /V and relative to the background shale p S implied that an AVO response was unlikely. Gradient analysis result for the synthetic seismic at the top and base of the two sands agreed with Rutherford's classification scheme for class IV AVO for 'Sand a' and no AVO response for 'Sand e'. AVO attribute analysis and impedance inversion of the seismic volumes confirmed AVO result for the two sands. The study established that AVO technique could be effectively used for fluid and lithology discrimination in the "Jay" Field, Niger Delta.

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Section: Synthetic Seismogrammentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

On the effectiveness of using quantitative avo analysis in fluid and lithology discrimination in an offshore Niger Delta Field, Nigeria

Adeoti¹,

Ikoro²,

Adesanya³

et al. 2018

Ife Journal of Science

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“…Potential hydrocarbon prospect is defined if a reservoir is trapped within structural traps such as fault blocks or stratigraphic traps. Seismic expressions from similar traps have been analysed as hydrocarbon presence (Toshev 2017;Adeoti et al 2018;Abdel-Fattah et al 2020) Hence, Root Mean Square (RMS) amplitude was extracted from the seismic volumes on the interpreted surface of the prospective reservoir and compared with the structured map to identify the hydrocarbon prospect studied. Post-stacked model-based inversion was conducted to extract elastic rock attribute for fluid presence detection from the seismic.…”

Section: Datasets and Methodologymentioning

confidence: 99%

Rock physics attribute analysis for hydrocarbon prospectivity in the Eva field onshore Niger Delta Basin

Ogbamikhumi

Igbinigie

2020

J Petrol Explor Prod Technol

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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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“…Simultaneous inversion was carried out to invert the seismic data into elastic properties descriptive of target reservoirs (Berge et al 2002;Pendrel et al 2000;Jason 2013). During the inversion, five angle stacks were simultaneously inverted to Z P , Z S and ρ from which other reservoir properties were derived for quantitative interpretation according to Bacon et al (2003); Contreras et al (2006) and Adeoti et al (2017). The angle stacks (6-12°, 12-18°, 18-26°, 26-32° and 32-42°) were tied to the wells (Sfn-01, Sfn-02, Sfn-05) to ensure good correlation of events and for accurate extraction of wavelets from each of the angle stacks.…”

Section: Simultaneous Inversionmentioning

confidence: 99%

“…This would require the integration of seismic and well data for enhanced vertical and lateral resolution for quantitative interpretation. Seismic inversion is a sophisticated tool used by the oil and gas companies to integrate 3D seismic data with petrophysical measurements from wells to improve spatial resolution, reduce risk in exploration and enhance development plan (Neves et al 2004;Avseth et al 2005;Alfaro et al 2007;Suslick et al 2009;Adeoti et al 2017). Since reflected seismic wave amplitudes are functions of acoustic/ elastic impedance, it becomes necessary to analysis seismic data stacked at various offset and angle of incidence ranges to exploit AVO (amplitude variation with offset)/ AVA (amplitude variation with angle) information in the data.…”

Section: Introductionmentioning

confidence: 99%

Hydrocarbon reservoir delineation using simultaneous and elastic impedance inversions in a Niger Delta field

Adesanya

Adeoti

Oyedele

et al. 2021

J Petrol Explor Prod Technol

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The global energy demand is increasing while production from mature fields is drastically reducing consequently, oil and gas industries are expanding activities into more challenging areas. The inability of the traditional seismic data to properly delineate hydrocarbon reservoirs from subtle seismic features in ‘Sandfish’ field located offshore, Niger Delta informed the use of simultaneous and elastic impedance inversion. The elastic and derived volumes from seismic inversion would reduce risk, enhance hydrocarbon discovery and optimize development plans in the study area. Four ‘Sandfish’ (Sfn) wells (Sfn-01, Sfn-02, Sfn-04 and Sfn-05), check-shots and 3D seismic data of five angle stacks (6–12°, 12–18°, 18–26°, 26–32° and 32–42°) were used in the study. Low frequency (0–2 Hz) models were generated from interpolation of high-cut-filtered compressional wave velocity log (P-sonic), shear wave velocity log (S-sonic) and density log guided by interpreted four seismic horizons. The low frequency models broaden the spectrum of the elastic volumes and also served as inversion constraints. The five partial angle stacks varying from 6–42° were simultaneously inverted using Jason’s Rock-Trace® inversion software which iterated trial inversions until the model sufficiently matched the seismic data. The near (6–12°) angle and far-far (32–42°) angle stacks were also inverted and compared with the inverted volumes from the simultaneous inversion. This was carried out to determine the effectiveness of near and far-far elastic impedance volume in delineating hydrocarbon reservoirs. The inverted elastic volumes P-impedance (ZP), S-impedance (ZS), density (ρ), near and far-far elastic and derived volumes lambda-rho (λρ), mu-rho (µρ), Poisson’s-ratio (σ) reveal vertical and lateral continuity of the reservoirs identified (K01, N01 and P01) at 2179 m, 2484 m and 3048 m, respectively. The delineated reservoirs showed good match with the sand tops away from the well control validated by a blind well test. The cross-plot of inverted ZP from simultaneous inversion and well ZP gave correlation coefficient of 86% indicative of high quality inverted volume which will reduce exploration risk. The plot of inverted ZP from simultaneous inversion and inverted far-far elastic volume reflected 82% correlation coefficient indicating that this method could be adopted in other fields with limited data and similar geological setting. Hence, the study has shown the efficacy of elastic volumes in delineating hydrocarbon reservoirs which can help locate optimum region for development wells.

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Lithology and fluid prediction from simultaneous seismic inversion over Sandfish field, Niger Delta, Nigeria

Cited by 13 publications

References 10 publications

On the effectiveness of using quantitative avo analysis in fluid and lithology discrimination in an offshore Niger Delta Field, Nigeria

On the effectiveness of using quantitative avo analysis in fluid and lithology discrimination in an offshore Niger Delta Field, Nigeria

Rock physics attribute analysis for hydrocarbon prospectivity in the Eva field onshore Niger Delta Basin

Hydrocarbon reservoir delineation using simultaneous and elastic impedance inversions in a Niger Delta field

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