scholarly journals Seismic attribute and petrophysics-assisted interpretation of the Nanushuk and Torok Formations on the North Slope, Alaska

2020 ◽  
Vol 8 (2) ◽  
pp. SJ17-SJ34 ◽  
Author(s):  
Shuvajit Bhattacharya ◽  
Sumit Verma
Keyword(s):  
Oil And Gas ◽  
Gamma Ray ◽  
Regional Scale ◽  
Rock Physics ◽  
Seismic Attributes ◽  
North Slope ◽  
Reservoir Properties ◽  
Seismic Attribute ◽  
Seismic Reflection Data ◽  
The North

Exploration of the Brookian sandstone reservoirs in the Nanushuk and Torok Formations on the North Slope of Alaska is a hot topic and presents opportunities to the oil and gas community because of their shallow depth, vast extent, and scope of development. The consecutive hydrocarbon discoveries announced by Repsol-Armstrong, Caelus Energy, and ConocoPhillips in 2015, 2016, and 2017 have indicated the presence of the vast recoverable resources on the North Slope in the Nanushuk and Torok reservoirs. We have investigated the detailed geophysical and petrophysical characteristics of these reservoirs. Our goal is to detect dominant geologic features in these formations using a combination of seismic attributes at the regional scale and analyze critical petrophysical and rock physics properties to evaluate formation heterogeneities and identify the reservoir targets by integrating well log and core data at the well scale. The Nanushuk Formation is expressed as topset reflections, whereas the Torok and gamma-ray zone formations are expressed as foresets and bottomsets on the seismic reflection data. Using seismic attributes, we mapped the extent of different geomorphological features, including shelf edges, channels, slides, and basin-floor fans, all with significant amplitude anomalies. The shelf edges continue for tens to hundreds of miles along the north/northwest and east–west directions, depending on the areas. The internal characters of these formations delineated by conventional well logs and advanced petrophysical analysis reveal their vertical heterogeneities and complexities, in terms of reservoir properties. We conclude that the reservoirs are vertically and laterally heterogeneous. These are thin-bedded low-resistivity reservoirs. Only a few zones in the parasequences are oil-saturated. We find that a combination of low [Formula: see text] ratio and acoustic impedance can be a useful proxy to detect the hydrocarbon-bearing sand intervals in these formations.

3D seismic imaging of the submarine slide blocks on the North Slope, Alaska

2020 ◽  
Vol 8 (4) ◽  
pp. SR37-SR44 ◽  
Author(s):  
Shuvajit Bhattacharya ◽  
Sumit Verma ◽  
Jonathan R. Rotzien
Keyword(s):  
Oil And Gas ◽  
Deep Ocean ◽  
Frictional Resistance ◽  
Seismic Attributes ◽  
North Slope ◽  
Submarine Landslides ◽  
Seismic Section ◽  
Submarine Channels ◽  
Submarine Slide ◽  
The North

Submarine landslides are mass movements that transport sediment across the continental shelf to the deep ocean. This phenomenon happens when the shear stress exceeds the frictional resistance of the slope. We analyze a variety of seismic attributes to interpret large submarine slide blocks on the North Slope, Alaska. Results show that the slide blocks appear as mounds with scarps associated with them on the seismic section. The slide blocks vary in size, depending on their distance away from the shelf. The pattern of the slide blocks affects the overlying sedimentation. Geological feature: Submarine slide blocks Seismic appearance: Mound-like steep ramp and scarp characteristics on seismic sections; blocky and irregular features with sharp boundaries on the horizon slices and seismic attributes Features with similar appearance: Mass-transport deposits; Remnant blocks; Reef deposits; Submarine channels; Gullies Formation: Torok Formation Age: Cretaceous Location: North Slope, Alaska Seismic data: Obtained from the Alaska Department of Natural Resources, Division of Oil and Gas, through the tax-credit program ( State of Alaska, 2017 , http://dggs.alaska.gov/gmc/seismic-well-data.php ) Analysis tools: Seismic attributes (such as coherent energy, Sobel-filter similarity, dip magnitude, and dip azimuth) and geobody extraction

scholarly journals APPLICATION OF DIRECT HYDROCARBON INDICATORS FOR OIL AND GAS PROSPECTING IN THE DNIPRO-DONETS DEPRESSION

2021 ◽  
pp. 99-108
Author(s):  
Sergiy VYZHVA ◽  
Ihor SOLOVYOV ◽  
Ihor МYKHALEVYCH ◽  
Viktoriia KRUHLYK ◽  
Georgiy LISNY
Keyword(s):  
Acoustic Impedance ◽  
Oil And Gas ◽  
Practical Importance ◽  
Seismic Attributes ◽  
Limited Range ◽  
Seismic Attribute ◽  
Tectonic Model ◽  
Hydrocarbon Traps ◽  
Attribute Analysis ◽  
Volumetric Images

Based on the results of numerous seismic studies carried out in the areas and fields of the Dnipro-Donets depression, the strategy to identify hydrocarbon traps in this region has been developed taking into account modern requirements for prospecting and exploration of gas and oil fields. The studies are designed to determine the favorable zones of hydrocarbon accumulations based on the analysis of the structural-tectonic model. A necessary element for solving such a problem is to aaply direct indicators of hydrocarbons to predict traps of the structural, lithological or combined type. It was determined that an effective approach to identify hydrocarbon traps in the region is attribute analysis employing seismic attributes such as seismic envelope, acoustic impedance or relative acoustic impedance. In most cases of practical importance, the analysis of the distribution of the values of these attributes turned out to be sufficient for performing the geological tasks. It is given an example of extracting additional useful information on the spatial distribution of hydrocarbon traps from volumetric images obtained from seismograms of common sources with a limited range of ray angles inclinations. To analyze the distributions of seismic attribute values, it is recommended to use the Geobody technology for detecting geological bodies as the most effective when using volumetric seismic data. The distributions of various properties of rocks, including zones of increased porosity or zones of presence of hydrocarbons are determined depending on the types of seismic attributes used in the analysis,. The use of several seismic attributes makes it possible to identify geological bodies saturated with hydrocarbons with increased porosity and the like. The paper provides examples of hydrocarbon traps recognition in the areas and fields of the Dnipro-Donets depression practically proved by wells. A generalization on the distribution of promising hydrocarbon areas on the Northern flank of the Dnipro-Donets depression and the relationship of this distribution with the identified structural elements of the geological subsoil is made. 

Geostatistics assisted by machine learning for reservoir property modeling: A case study in presalt carbonates of Buzios Field, Brazil

2021 ◽  
Vol 40 (12) ◽  
pp. 876-885
Author(s):  
Danilo Jotta Ariza Ferreira ◽  
Gabriella Martins Baptista de Oliveira ◽  
Thais Mallet Castro ◽  
Raquel Macedo Dias ◽  
Wagner Moreira Lupinacci
Keyword(s):  
Effective Porosity ◽  
Reservoir Properties ◽  
Predictive Capacity ◽  
Seismic Attribute ◽  
Blind Test ◽  
The North ◽  
Basal Section ◽  
Petrophysical Modeling ◽  
Embedded Model ◽  
Porosity And Permeability

An embedded model estimator (EMBER) petrophysical modeling algorithm has been applied to obtain effective porosity and permeability within the presalt carbonate reservoirs of the Barra Velha Formation in Buzios Field, Santos Basin. This advanced methodology was used due to the heterogeneity and complexity of the reservoirs, which makes modeling by conventional geostatistical methodologies difficult. For effective porosity modeling, we chose one facies model, one stratigraphic seismic attribute (acoustic impedance), and one structural seismic attribute (local flatness) as secondary variables. Permeability was modeled by using the best effective porosity simulation result as a secondary variable. Our results demonstrate that average effective porosity and permeability were 0.10 v/v and 440 md, respectively, indicating good reservoir quality throughout the studied area. A vertical trend of high effective porosities and permeabilities for the basal and uppermost reservoir sections was identified in our results, as well as a trend with lower values for these reservoir properties for the intermediate reservoir section. The lower section of the formation presented more continuity, and we infer it to be the best reservoir interval. We observed two horizontal trends for these reservoir properties at the formation top: one of higher values aligned to the north–south direction at the structural highs and another of lower reservoir properties related to isolated structural lows within structural highs. Correlation between modeled results and the blind test ANP-1 well upscaled properties was high, and upscaled well-log property distributions were preserved in the EMBER simulations, proving the predictive capacity of the algorithm. Finally, conditional distributions analysis indicated that the basal section of the Barra Velha Formation presents higher uncertainty for the estimation of effective porosity. Even though this interval is considered to have the best reservoir characteristics, decision making should be done with caution for this section.

A comprehensive analysis of conditions and features of oil-and-gas content within the Akhlovskaya structural zone (the North Caucasus)

2021 ◽  
pp. 25-38
Author(s):  
I. I. Bosikov ◽  
A. I. Mazko ◽  
A. V. Mayer ◽  
O. V. Gagarina
Keyword(s):  
Oil And Gas ◽  
Gas Content ◽  
North Caucasus ◽  
Reservoir Properties ◽  
Resource Base ◽  
Entire Area ◽  
The North ◽  
Urgent Task ◽  
Porosity Coefficient ◽  
Saturated Thickness

At the present stage, the development of the oil industry of the Russian Federation is impossible without replenishing the resource base, and therefore an urgent task is to analyze and assess the conditions and characteristics of oil-andgas content in unexplored regions.Purpose of the study is an analysis and an assessment of reservoir properties of rocks of the Aptian horizon Р1+2- К2 within the Akhlovskaya structure.We analyzed the graphs of the distribution of indicators in wells R-212 and R-213 in the Akhlovsky area and concluded that the reservoir is heterogeneous, and there are interlayers of mudstones with other reservoir properties and geophysical characteristics. The following pairs of parameters (porosity coefficient and oil-saturated thickness of rocks, rock resistivity and porosity coefficient, rock resistivity and oil-saturated thickness of rocks) have a significant positive correlation. Having studied the distribution of indicators in the Akhlovsky area for wells R-212 and R-213 along one horizon, we concluded that these indicators differ very slightly, which indicates the homogeneity of the reservoir properties. Qualitative indicators Qualitative indicators don't change. Thus, we can expect similar indicators within the entire area of the explored layer Р1+2- К2 in the territory of the Akhlovsky area.

Surface to subsurface correlation of the Middle-Upper Triassic Shublik Formation within a revised sequence stratigraphic framework

2020 ◽  
Vol 8 (2) ◽  
pp. SJ1-SJ16
Author(s):  
William A. Rouse ◽  
Katherine J. Whidden ◽  
Julie A. Dumoulin ◽  
David W. Houseknecht
Keyword(s):  
Large Scale ◽  
Gamma Ray ◽  
Upper Triassic ◽  
North Slope ◽  
Depositional Sequences ◽  
Sequence Stratigraphic ◽  
The North ◽  
Depositional Patterns ◽  
Resource Exploration ◽  
Unconventional Resource

Recent work on cores and outcrops of the Middle-Upper Triassic Shublik Formation has facilitated surface to subsurface correlation of depositional sequences across the Alaska North Slope. Five transgressive-regressive depositional sequences have been defined within three large-scale stratigraphic units. Outcrop spectral gamma-ray (GR) profiles were used to correlate observed stacking patterns with nearby exploration wells, and GR logs from 161 exploration wells were used to correlate the three large-scale stratigraphic units across the North Slope and nearby offshore. Interpretations of depositional facies and sequence stratigraphy in cores from 26 wells were used to corroborate regional correlations. Isochore maps constructed for each of the three stratigraphic units illustrate the influence of accommodation on depositional patterns and suggest reactivation of several older tectonic elements during Shublik deposition. An isochore map of the richest, oil-prone interval of the Shublik Formation reveals a thick pod south of Harrison Bay, the eastern part of which lies beneath a recent giant Shublik-sourced oil discovery in the Cretaceous Nanushuk Formation. In addition, when integrated with thermal maturity, this isochore map may provide leads for areas that are optimal for unconventional resource exploration.

scholarly journals USE OF QUANTITATIVE DATA OF 3D SEISMIC EXPLORATION FOR DETECTION OF TRAPS OF HYDROCARBONS WITH IN THE NORTH SIDE OF THE DNIEPER-DONETSK DEPRESSION

2020 ◽  
pp. 35-41
Author(s):  
S. Vyzhva ◽  
I. Solovyov ◽  
I. Mihalevich ◽  
V. Kruhlyk ◽  
G. Lisny
Keyword(s):  
Acoustic Impedance ◽  
Seismic Signal ◽  
Seismic Attributes ◽  
Limited Range ◽  
Seismic Exploration ◽  
High Porosity ◽  
Seismic Attribute ◽  
The North ◽  
Hydrocarbon Traps ◽  
Northern Side

Based on the results of numerous seismic surveys conducted on the areas and deposits of the northern side of the Dnieper-Donetsk depression, an appropriate strategy for detecting hydrocarbon traps in this region has been determined. This takes into account modern requirements for exploration and prospecting of gas and oil deposits. They consist in determining the probable zones of accumulation of hydrocarbons based on the analysis of the structural-tectonic model. At the same time, the use of direct hydrocarbon indicators to predict structural, lithological or combined traps is also a necessary element in solving this problem. It has been shown that an effective approach to detecting hydrocarbon traps in this region is attribute analysis using seismic attributes such as seismic signal envelope, acoustic impedance or relative acoustic impedance. In most practically important cases, the analysis of the distribution of values of these attributes was sufficient to solve geological problems. At the same time, an example of extracting additional useful information on the spatial distribution of hydrocarbon traps from volumetric seismic images obtained from seismograms of common sources with a limited range of seismic angle inclinations is given. To analyze the distributions of seismic attribute values it is recommended to use geobody technology as the most effective one when using volumetric seismic data. Depending on the combination of seismic attributes involved in the analysis, the distributions of different properties of rocks are determined, in particular the zone of increased porosity or the presence of hydrocarbons. Analysis with the simultaneous use of several seismic attributes allows to directly identify hydrocarbon-rich geological bodies with high porosity and the like. The paper presents examples of detection of hydrocarbon traps in the areas and deposits of the northern side of the Dnieper-Donetsk depression, which are confirmed by drilled wells. An example of providing recommendations for wells drilling using the distributions of values of different seismic attributes is given. Generalizations are made on the distribution of promising areas for the presence of hydrocarbons on the northern side of the Dnieper-Donetsk depression and the ratio of this distribution with the identified structural elements of the geological environment.

scholarly journals Biot's equations-based reservoir parameter inversion using deep neural networks

2021 ◽  
Vol 18 (6) ◽  
pp. 862-874
Author(s):  
Fansheng Xiong ◽  
Heng Yong ◽  
Hua Chen ◽  
Han Wang ◽  
Weidong Shen
Keyword(s):  
High Efficiency ◽  
Synthetic Data ◽  
Rock Physics ◽  
Seismic Attributes ◽  
Inversion Method ◽  
Reservoir Properties ◽  
Shear Moduli ◽  
Parameter Inversion ◽  
Reservoir Parameter ◽  
Biot’S Equations

Abstract Reservoir parameter inversion from seismic data is an important issue in rock physics. The traditional optimisation-based inversion method requires high computational expense, and the process exhibits subjectivity due to the nonuniqueness of generated solutions. This study proposes a deep neural network (DNN)-based approach as a new means to analyse the sensitivity of seismic attributes to basic rock-physics parameters and then realise fast parameter inversion. First, synthetic data of inputs (reservoir properties) and outputs (seismic attributes) are generated using Biot's equations. Then, a forward DNN model is trained to carry out a sensitivity analysis. One can in turn investigate the influence of each rock-physics parameter on the seismic attributes calculated by Biot's equations, and the method can also be used to estimate and evaluate the accuracy of parameter inversion. Finally, DNNs are applied to parameter inversion. Different scenarios are designed to study the inversion accuracy of porosity, bulk and shear moduli of a rock matrix considering that the input quantities are different. It is found that the inversion of porosity is relatively easy and accurate, while more information is needed to make the inversion more accurate for bulk and shear moduli. From the presented results, the new approach makes it possible to realise accurate and pointwise inverse modelling with high efficiency for actual data interpretation and analysis.

scholarly journals Geophysical imaging of porosity variations in the Danish North Sea chalk

2008 ◽  
Vol 15 ◽  
pp. 17-20 ◽  
Author(s):  
Tanni Abramovitz
Keyword(s):  
North Sea ◽  
Seismic Reflection ◽  
Seismic Inversion ◽  
Rock Properties ◽  
Well Log ◽  
Reservoir Properties ◽  
Seismic Reflection Data ◽  
Log Data ◽  
The North ◽  
The North Sea

More than 80% of the present-day oil and gas production in the Danish part of the North Sea is extracted from fields with chalk reservoirs of late Cretaceous (Maastrichtian) and early Paleocene (Danian) ages (Fig. 1). Seismic reflection and in- version data play a fundamental role in mapping and characterisation of intra-chalk structures and reservoir properties of the Chalk Group in the North Sea. The aim of seismic inversion is to transform seismic reflection data into quantitative rock properties such as acoustic impedance (AI) that provides information on reservoir properties enabling identification of porosity anomalies that may constitute potential reservoir compartments. Petrophysical analyses of well log data have shown a relationship between AI and porosity. Hence, AI variations can be transformed into porosity variations and used to support detailed interpretations of porous chalk units of possible reservoir quality. This paper presents an example of how the chalk team at the Geological Survey of Denmark and Greenland (GEUS) integrates geological, geophysical and petrophysical information, such as core data, well log data, seismic 3-D reflection and AI data, when assessing the hydrocarbon prospectivity of chalk fields.

scholarly journals Knowledge Co-production in Contested Spaces: An Evaluation of the North Slope Borough – Shell Baseline Studies Program

ARCTIC ◽  
2019 ◽  
Vol 72 (1) ◽  
pp. 43-57 ◽  
Author(s):  
Nathan P. Kettle
Keyword(s):  
Oil And Gas ◽  
Steering Committee ◽  
Lessons Learned ◽  
The Arctic ◽  
North Slope ◽  
Oil And Gas Development ◽  
Boundary Organization ◽  
Contested Spaces ◽  
The North ◽  
Trade Offs

Supporting the development of trusted and usable science remains a key challenge in contested spaces. This paper evaluates a collaborative research agreement between the North Slope Borough of Alaska and Shell Exploration and Production Company—an agreement that was designed to improve collection of information and management of issues associated with the potential impacts of oil and gas development in the Arctic. The evaluation is based on six categories of knowledge co-production indicators: external factors, inputs, processes, outputs, outcomes, and impacts. Two sources of data were used to assess the indicators: interviews with steering committee members and external science managers (n = 16) and a review of steering committee minutes. Interpretation of the output and outcome indicators suggests that the Baseline Studies Program supported a broad range of research, though there were differences in how groups perceived the relevance and legitimacy of project outcomes. Several input, process, and external variables enabled the co-production of trusted science in an emergent boundary organization and contested space; these variables included governance arrangements, leveraged capacities, and the inclusion of traditional knowledge. Challenges to knowledge co-production on the North Slope include logistics, differences in cultures and decision contexts, and balancing trade-offs among perceived credibility, legitimacy, and relevance. Reinforced lessons learned included providing time to foster trust, developing adaptive governance approaches, and building capacity among scientists to translate community concerns into research questions.

scholarly journals Using Seismic Attributes in seismotectonic research: an application to the Norcia's Mw = 6.5 earthquake (30th October 2016) in Central Italy

2019 ◽  
Author(s):  
Maurizio Ercoli ◽  
Emanuele Forte ◽  
Massimiliano Porreca ◽  
Ramon Carbonell ◽  
Cristina Pauselli ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Central Italy ◽  
Seismic Attributes ◽  
Seismic Attribute ◽  
Data Set ◽  
Epicentral Zone ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
Reflection Data ◽  
Attribute Analysis

Abstract. In seismotectonic studies, seismic reflection data are a powerful tool to unravel the complex deep architecture of active faults. Such tectonic structures are usually mapped at surface through traditional geological surveying whilst seismic reflection data may help to trace their continuation from the near-surface down to hypocentral depth. In this study, we propose the application of the seismic attributes technique, commonly used in seismic reflection exploration by oil industry, to seismotectonic research for the first time. The study area is a geologically complex region of Central Italy, recently struck by a long-lasting seismic sequence including a Mw 6.5 main-shock. A seismic reflection data-set consisting of three vintage seismic profiles, currently the only available across the epicentral zone, constitutes a singular opportunity to attempt a seismic attribute analysis. This analysis resulted in peculiar seismic signatures which generally correlate with the exposed surface geologic features, and also confirming the presence of other debated structures. These results are critical, because provide information also on the relatively deep structural setting, mapping a prominent, high amplitude regional reflector that marks the top basement, interpreted as important rheological boundary. Complex patterns of high-angle discontinuities crossing the reflectors have been also identified. These dipping fabrics are interpreted as the expression of fault zones, belonging to the active normal fault systems responsible for the seismicity of the region. This work demonstrates that seismic attribute analysis, even if used on low-quality vintage 2D data, may contribute to improve the subsurface geological interpretation of areas characterized by high seismic potential.

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