SEISMIC FACIES ANALYSIS AND STRUCTURAL INTERPRETATION OF DEEPWATER NW SABAH

The deepwaters of NW Sabah has been an interesting site for deepwater hydrocarbon exploration in Malaysia. Up to now, the exploration in this is mainly focused to the Late Miocene until the Pliocene siliciclastic sediment reservoirs distribution at the shelf edge. This paper shows a gross seismic facies mapping analysis and structural interpretation of regional deepwater NW Sabah especially at Sabah Trough. To convert depth, all seismic lines were picked and tied with selected wells. The results of the interpretation were then summarized and presented with relation to regional tectonic events. Eight seismic stratigraphic units, six seismic facies together with five sequence boundaries were recognized. Multichannel reflection 2D seismic data, gamma ray logs and biostratigraphy description from the three wells at deepwater fold-thrust belt and published tectono-stratigraphic scheme from Dangerous Grounds (Sabah Platform) in South China Sea were selected in this study. The propose of this study is to document the relevance of regional tectonic event between Dangerous Ground and Sabah Trough.

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Subsurface basement, structure, stratigraphy, and timing of regional tectonic events affecting the Guajira margin of northern Colombia

Interpretation ◽

10.1190/int-2020-0016.1 ◽

2020 ◽

Vol 8 (4) ◽

pp. ST69-ST105

Author(s):

Eleine Vence ◽

Paul Mann

Keyword(s):

Continental Margin ◽

Late Eocene ◽

Seismic Facies ◽

Tectonic Events ◽

Regional Tectonic ◽

Basin Formation ◽

The Caribbean ◽

Basement High ◽

Marine Seismic ◽

Sea Fan

We have combined previous data from Mesozoic-Cenozoic outcrops in the Guajira Peninsula of northern Colombia with regional gravity, bathymetric, and seismic interpretations to demonstrate the existence of a 280 km long western extension of the Great Arc of the Caribbean (GAC) along the continental margin of Colombia. Seismic data reveal an 80–100 km wide domal-shaped basement high that exhibits internal chaotic seismic facies. This elongate and domal-shaped structure extends 1800 km from the Aves Ridge in the Caribbean Sea to the study area in offshore Colombia. The western extension of the GAC in Colombia and western Venezuela is buried by 700–3000 m of continental margin sedimentary rocks as a result of the GAC colliding earlier with the Colombian margin (Cretaceous-early Paleogene collision) than its subaerially exposed eastern extension along the Leeward Antilles ridge (late Paleogene-Neogene). Our compilation of geologic information from the entire GAC reveals that GAC magmatism occurred from 128 to 74 Ma with magmatism ages progressively younger toward the east. Six upper Eocene to recent marine seismic sequences overlying the domal basement high of the GAC have been mapped by our analysis of 2400 km of seismic lines and 12 well logs. Based on subsurface mapping correlated with well-log information and onland geology in the Guajira Peninsula, these six sequences record four major deformational events: (1) late Eocene rifting in an east–west direction produced half-grabens in the northern part of the area, (2) Oligocene transtension in the southern part of the area expressed by right-lateral Oligocene strike-slip faulting and extensional basin formation, (3) early-middle Miocene transtension, and (4) late Miocene-early Pliocene Andean uplift accompanied by rapid erosion and clastic infilling of offshore basins by the Magdalena delta and deep-sea fan. The significance of this basin framework is discussed for known and inferred hydrocarbon systems.

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Predicting the thickness of sand strata in a sand-shale interbed reservoir based on seismic facies analysis

Journal of Geophysics and Engineering ◽

10.1093/jge/gxaa015 ◽

2020 ◽

Author(s):

Huilin Li ◽

Rui Gao ◽

Yanghua Wang

Keyword(s):

Spatial Distribution ◽

Gamma Ray ◽

Facies Analysis ◽

Thickness Distribution ◽

Seismic Facies ◽

Seismic Responses ◽

Entire Study ◽

Thickness Prediction ◽

Sedimentary Microfacies ◽

Seismic Facies Analysis

Abstract Seismic facies analysis is of great significance for the detection of residual oil in a sand-shale interbed reservoir. In this study, we propose to predict spatial distribution of sand thickness over a reservoir, based on seismic facies analysis. The target reservoir is a thin sand-shale interbed layer, and the layer thickness varies between 2 and 10 m. The thickness of sand strata within the reservoir layer appears to have a fragmentary distribution in lateral space. Thin thickness and fragmentary distribution are two factors that cause difficulty in sand thickness prediction. To tackle this problem, this study adopted a three-stage strategy. First, the reservoir over the entire study area was classified into five different lithofacies, following sedimentary microfacies analysis against the characteristics of gamma-ray logging data, and the corresponding seismic responses were meticulously depicted. Then, exploiting these seismic responses, or seismic facies, the spatial distribution of the gamma-ray values was evaluated within the thin sand-shale interbed reservoir. Finally, the spatial distribution of the sand thickness was predicted according to the spatial distribution of the gamma-ray values. The prediction was conducted independently for each seismic facies, rather than in a non-discriminatory manner. Comparing the prediction to the actual evaluation derived from well-logging data demonstrated that the thickness distribution resulting from seismic data has a high accuracy, because of the facies-based analysis.

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Exploration for a Frontier Salt Basin in Southwest Oman

GeoArabia ◽

10.2113/geoarabia0602159 ◽

2001 ◽

Vol 6 (2) ◽

pp. 159-176

Author(s):

Mark F. Blood

Keyword(s):

Lower Cambrian ◽

Facies Analysis ◽

Gravity Data ◽

The Other ◽

Seismic Facies ◽

Gravity Modeling ◽

Lower Paleozoic ◽

Structural History ◽

Seismic Facies Analysis ◽

Seismic Lines

ABSTRACT An undrilled Infracambrian-lower Paleozoic salt basin is interpreted as being present in the Dhofar area of southwest Oman. A re-evaluation of the existing seismic and gravity data indicated that the basin is located immediately north of a major NE-orientated basement feature known as the Ghudun-Khasfah High. The basin is centered in the southern part of the Al Hashman Block 36 and the northern part of Mudayy Block 38, both operated by Phillips. Studies conducted by Phillips suggest that the basin has a similar structural history and pre-Silurian stratigraphy to the known salt basins of Oman. New stratigraphically deeper Paleozoic and Infracambrian exploration plays that are proven in the other Oman salt basins are proposed for this undrilled basin. The new plays rely on an unproven Infracambrian Huqf source. Source and reservoir degradation through widespread post-Huqf deformation is possible, but structural modeling and seismic facies analysis, together with the detection of significant micro-seepage anomalies, suggest otherwise. In addition, the identification and gravity modeling of what appear to be salt features on seismic lines support the presence of Lower Cambrian salt swells and piercement structures. The salt features are believed to be age equivalent to the Ara salt section of the upper Huqf Supergroup present in the other salt basins. Phillips has named this potential salt basin the Ghudun Salt Basin.

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The sedimentary expression of regional tectonic events during the Miocene-Pliocene transition in the southern Cyprus basins

Geological Magazine ◽

10.1017/s001675680002238x ◽

1989 ◽

Vol 126 (3) ◽

pp. 291-299 ◽

Cited By ~ 30

Author(s):

F. Orszag-Sperber ◽

J. M. Rouchy ◽

P. Elion

Keyword(s):

Mediterranean Region ◽

Tectonic Stress ◽

East Mediterranean ◽

The South ◽

Tectonic Event ◽

Tectonic Events ◽

Southern Cyprus ◽

Regional Tectonic ◽

East Mediterranean Region ◽

Main Change

AbstractA well-known tectonic event affecting the East Mediterranean region, generally referred to as ‘the’ Miocene–Pliocene phase, occurs at, or near the Miocene–Pliocene boundary. Recent sedimentological studies in Cyprus indicate that this ‘event’, in fact, is complex. The Tortonian–Lower Pliocene period is marked by a stress involving an N20 extension in the Polemi and Pissouri basins and by an N100 extension in the Psematismenos basin. Sedimentological studies have demonstrated three tectonic pulsations during Messinian time, prior to the Pliocene transgression. These are expressed by two episodes of seismic brecciation, and a palaeo-emersion is indicated by palaeosols and detrital discharges. These phenomena suggest brief tectonic instability during Messinian time. Microtectonic studies in the South Troodos basins of Cyprus reveal that the main change in tectonic stress does not coincide with the Miocene–Pliocene contact but occurs at the end of Lower Pliocene time. The authors conclude that the so-called Miocene–Pliocene ‘event’, in reality, is a series of subtle tectonic pulsations recorded clearly by sedimentary parameters.

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Coblending of seismic attributes for interpretation of channel geometries in Rence Field of Niger Delta, Nigeria

Interpretation ◽

10.1190/int-2014-0083.1 ◽

2015 ◽

Vol 3 (4) ◽

pp. T183-T195 ◽

Cited By ~ 6

Author(s):

Augustine Ifeanyi Chinwuko ◽

Ajana Godwin Onwuemesi ◽

Emmanuel Kenechukwu Anakwuba ◽

Clement Udenna Onyekwelu ◽

Harold Chinedu Okeke ◽

...

Keyword(s):

Niger Delta ◽

Water Saturation ◽

Seismic Attributes ◽

Hydrocarbon Exploration ◽

Seismic Facies ◽

Petrophysical Analysis ◽

Net To Gross ◽

Seismic Facies Analysis ◽

Well Data ◽

Channel Deposits

Coblending of seismic attributes is used in the interpretation of channel geometries in the Rence Field of Niger Delta, Nigeria. We aimed at seismically defining the geometries of hydrocarbon reservoirs with particular emphasis on channels in the shallow marine (offshore) Niger Delta. The coblending application enhanced the ease of detection and the continuity of the channels, leaving the channel environs unchanged. The result of the seismic facies analysis revealed that the Rence Field can be distinguished into two seismic facies, namely, layered complexes and chaotic complexes. The result of well to seismic ties revealed high- and low-amplitude reflection events for sand and shale units, respectively. Seismic structural interpretation of the Rence Field revealed 4 major regional faults and 12 minor faults. Seven of the faults were antithetic, and the rest were synthetic faults. One mega-channel feature that trends east–west was identified in the attribute maps generated. It was characterized by sinuosity of 1.3, with a length of 22,500 m, and a distance of 17,500 m. The average depth of the channel was approximately 170 m with amplitude of 1670 m and the wavelength as high as 7640 m. A depositional model generated from the attribute maps indicated a prograding fluvial environment of deposition. The attribute map also determined that there was shifting in the location of barrier bars within the area. This shifting could be attributed to the growth fault mechanism. At the stoss side of the sinusoidal channel, there were prominent sand point bar sequences. The petrophysical analysis of the well data revealed 90% net-to-gross, 28% porosity, 27% volume of shale, and 24% water saturation indicating that the reservoir was of pay quality. Based on the petrophysical analysis, results, and identification of channel deposits, the study area proved highly promising for hydrocarbon exploration.

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Seismo-Structural Interpretation and Petrophysical Evaluation of Ugwu-Field, Coastal Swamp Depositional Belt of the Niger Delta Basin

Journal of Applied Sciences and Environmental Management ◽

10.4314/jasem.v24i9.16 ◽

2020 ◽

Vol 24 (9) ◽

pp. 1583-1591

Author(s):

E.B. Ugwu ◽

S.A. Ugwu ◽

C.U. Ugwueze ◽

S.U. Eze ◽

M.A. Bello

Keyword(s):

Niger Delta ◽

Gamma Ray ◽

Hanging Wall ◽

High Amplitude ◽

Seismic Facies ◽

Well Log ◽

Structural Interpretation ◽

Petrophysical Parameters ◽

North East ◽

Petrophysical Evaluation

Structural interpretation of 3-D seismic data and well log have been applied to unravel hydrocarbon entrapment pattern and petrophysical parameters of X-field within the coastal swamp region of the Niger Delta.. Four reservoir intervals (A, B, C and D) delineated as (W-026, 032, 042 and 048) using gamma ray and resistivity log response. Structural interpretation for inline 5158 revealed four horizons (A, B, C and D) and eight (8) faults labelled (F1, F2, F12, F13, F21, F22, F23, and F24) were mapped. It was observed that the hanging wall block due to reverse drag or rollover anticline slided over fault F12 and created fault F2, thereby creating subsidence where sediments can be deposited. Therefore, faults F2 and F12 created rollover structures which cuts across the entire four reservoirs and invaluably responsible for trapping of hydrocarbon in the field. RMS map developed for horizons ‘A’ and ‘B’ revealed high amplitude anomalies, while variance attribute for both horizons showed relatively uniform lithology observed from east to west across the study area. While from north-east to south west, variance was observed to increase relatively which indicates different lithology. These trend exposes dipping of the channel fill at both flanks by creating extensive faulting. Results of petrophysical evaluation for reservoirs ‘A’ and ‘B’ across the four wells were analyzed. For reservoir ‘A’, porosity values of 32.8%, 24.8%, 25.9% and 27.1% were obtained for wells W-048, 042, 026 and 032 respectively with an average of 27.65%, while for reservoir ‘B’ porosity values of 26.83%, 26.93%, 25.59% and 27.99% for wells W-048, 042, 026 and 032 were obtained respectively with an average of 26.84%. This porosity values were rated very good to excellent for reservoir ‘A’ and very good for reservoir ‘B’, while Permeability values of the order (K > 1000mD) were obtained for both reservoirs across the four wells and is rated excellent. Hydrocarbon saturation (Shc) across the four wells averages at 68.57% for reservoir ‘A’ and 68.67% for reservoir ‘B’ which is high. Log motifs using gamma ray log for well-026 was integrated with seismic facies to infer on depositional environment of the reservoirs horizons showed a combination of serrated funnel/blocky shape log response and coarsening upward cycles. For reservoirs ‘A’, ‘B’ and ‘C’ the log shape pattern indicates deposition in a fluvial / tidal, channel environment while for reservoir ‘D’ the pattern indicates deposition in deltaic front environment. Isochore maps computed for horizons ‘A’ and ‘B’, shows that horizon ‘A’ is relatively thick and this pattern suggests increased tectonic activities during deposition of reservoir ‘A’ and is an indication that reservoir ‘A’ is a synrift deposit. Keywords: 3-D Seismic interpretation, Faults, Seismostratigraphy, Well log, Seismic Attributes, Petrophysical parameters

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