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Volume 42, Issue 3, 2024
- Technical Article
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Sand Fairways Delineation by Post-Stack Seismic Inversion and Seismic Wave form Classification Integration, Sitra Area, North Western Desert, Egypt
Authors Ahmed H. Hafeez, Ahmed S. Abu-El Ata, Ashraf E. Ghonimi, Amir M. Lala and Ali M. BakrAbstractAbu Roash ‘C’ and ‘E’ oil and gas reservoirs are targets of the most exploration and development wells in Sitra concession, which is in the northern part of the Egyptian Western Desert.
Delineation of a fairway of reservoir quality Cretaceous Albian sandstone (Abu Roash C and E Sand) in Sitra Concession of the Abu El-Gharadig basin is one of the key challenges for the success of exploration and development wells. The integration between post stack seismic inversion and seismic wave form classification is important to identify the sand distributions and reservoir geometries. The aim of this work is illustrating the uses of such seismic interpretation techniques in revealing the structural and stratigraphic elements of two main reservoir units.
The study of reservoir distributions is one of the main elements needed to be known for oil and gas exploration and exploitation, in addition to uncertainty analysis of volumes calculations.
In this work, seismic wave form classifications SWC and post stack seismic inversion techniques were carried out for the available seismic data and output on two surfaces: the first horizon corresponds to the top Abu Roash C and the second horizon corresponds to the top Abu Roash E, which are the main reservoirs in the area.
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Mapping and Detection of Small-Scale Magnetic Anomalies with Shipborne Vector Magnetometer Measurements. Case Studies in the Coastal Shallow Waters of the Bay of Brest and Iroise Sea (France)
Authors Jean-François Oehler, Guy Marquis, Verena Schifano, Hugo Reiller and Sylvain LucasAbstractMarine magnetic surveys have traditionally been performed towing scalar magnetometers behind the vessel. We have investigated the possibility of replacing them by shipborne vector magnetometers. For this purpose, we have acquired two surveys in the shallow waters of the Bay of Brest and the Iroise Sea (NE Atlantic). Coincident shipborne vector and towed-scalar magnetometers have been deployed from two carriers: at the prow of the 8 m-long launch VH Goéland and on the mast of the 59 m-long hydrographic vessel BH2 Laplace. The shipborne vector sensor is significantly affected by noise related to the ship’s remanent and induced magnetisations than can reach thousands of nanoteslas (nT). We have mitigated these effects by acquiring figures of merit and computing compensation factors that removed over 95% of this noise. After low-pass filtering and offset corrections, we found that the resulting magnetic anomaly maps are fairly close to those obtained with the coincident towed-scalar data. We have resolved anomalies as small as 10 nT related to anthropogenic metal objects and 20 nT related to geological features interpreted as dolerite dikes. These results confirm that shipborne vector magnetometers could be a valid alternative to towed-scalar systems, especially in coastal shallow and busy waters.
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- Special Topic: Reservoir Monitoring
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Full Elastic Imaging – Shenzi Field, Deep-Water Gulf of Mexico
Authors Allon Bartana, Jeff Codd, David Kessler, Joakim Blanch, Drew Eddy, Ramses Meza, Varendra Rambaran, J. P. Blangy and Yi HuangSummaryOver the years Shenzi field in deep-water Gulf of Mexico became a test bed for evaluation of new seismic acquisition and processing technologies. These include 3D narrow azimuth streamer data, 3D-rich azimuth streamer data, and recently 3D OBN data (Mifflin et al, 2021). On the processing side, many types of processing techniques were used to image the various data types recorded over Shenzi field, from 3D ray-based Kirchhoff summation PSDM to Acoustic RTM PSDM and Acoustic FWI imaging. In the work presented here we demonstrate the advantages of Full Elastic imaging using the OBN dataset acquired by Woodside Energy in 2019 to better image the sub-salt field.
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A Novel Geophysical Method to Monitor Ultra-Shallow Reservoirs: Mapping of Soil Moisture Content in Subsiding Peatlands to Forecast Drought Effects and CO2 Emissions
Authors Stefan Carpentier, Sjef Meekes, Arnoud Frumau, Manon Verberne, Thibault Candela and Kay KosterAbstractManaged peatland deterioration by microbial oxidation is a worldwide process that leads to the gradual disappearance of these highly organic and fertile soils. Peat oxidation is often the result of aerated top soils by artificially kept low groundwater levels, which enhances aerobic microbial breakdown of organic carbon. This process leads to both subsidence and large quantities of CO2 emissions. Furthermore, artificially drained peatlands are vulnerable to salinisation when proximal to coastlines, and fires when situated in dry and warm climatic zones.
The decrease of the soil moisture content (SMC) and groundwater level (GL) during drought episodes can cause both subsidence and accelerated CO2 emissions, both of which are big issues in the Netherlands. Severe drought results in salinisation of groundwater and greenhouse gas emissions by oxidising peat, and therefore is a societal burden to the Netherlands and worldwide. Furthermore, in coastal lowlands drought accelerates subsidence, leading to relative sea-level rise.
Both SMC and GL are proven to be mappable using geophysical methods. Multi-coil offset Electro-Magnetic Induction (EMI) has high potential to map peat properties for managed peatlands from apparent electrical conductivity (ECa). Studies show that by using EMI, it is possible to obtain ECa for different depth intervals, which are used to estimate soil organic carbon. Furthermore, EMI has a long application history of non-invasive SMC mapping, although obtained ECa also depends on other factors, such as variations in soil composition, density, and pore water conductivity (σw).
TNO and SoilMasters, an expert EM company, employ a mobile electromagnetic mapping system to recover the soil moisture content, a crucial ingredient in these issues. These innovative Electro Magnetic Induction (EMI) measurements of the soil moisture content are used in combination with geodetic and CO2 measurements to forecast subsidence and CO2 emissions.
We present a time-lapse pilot study for SMC and GL employing EMI in a managed peatland in the central peat-rich delta plain of the Netherlands, near the city of Gouda. Furthermore, we use soil moisture probe and GL measurements at fixed point locations to confront the obtained ECa. We also link the obtained calibrated soil moisture maps to observed subsidence, and CO2 NEE (Net Ecosystem Exchange) flux. The resulting highly correlated measurements and observations can be well explained by precipitation and drought patterns. This makes our findings good proxies for spatio-temporal prediction of subsidence and CO2 emissions for dry and wet spells by monitoring measurements of EMI.
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Impact of Effective Pressure on Acoustic Impedance-Velocity Linear Relationships: Ordovician Red River ‘C’ Zone Reservoir, Williston Basin, USA
More LessAbstractP-wave and S-wave impedance are linearly related with their respective velocities at both low and high levels of effective pressure. The study was carried out at the core scale and brine-saturated state of carbonate core samples with variable porosities. The slopes, derived from linear-linear crossplots of P-wave and S-wave impedance versus their respective velocities, exhibit close quantitative agreement from one level of effective pressure to another. The intercept values are all negative and exhibit significant increase, going from low to high effective pressures. For practical purposes, the impedance-velocity relationships are both rock-typing and porosity-discriminating criteria. The high correlation coefficient exhibited in the crossplots at all levels of differential pressure signifies that the relationships could potentially be used to investigate carbonate reservoirs at different depths and rock competencies. The large differential between intercept values for P-waves and S-waves could be a diagnostic tool for discriminating carbonate reservoirs. These results show that the impedance-velocity linear relationships for P-wave and S-wave could become important tools for predictive and quantitative reservoir characterisation in well logs and seismic data.
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Volumes & issues
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Volume 42 (2024)
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Volume 41 (2023)
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Volume 40 (2022)
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Volume 39 (2021)
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Volume 38 (2020)
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Volume 37 (2019)
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Volume 36 (2018)
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Volume 35 (2017)
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Volume 34 (2016)
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Volume 33 (2015)
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Volume 32 (2014)
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Volume 31 (2013)
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Volume 30 (2012)
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Volume 29 (2011)
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Volume 28 (2010)
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Volume 27 (2009)
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Volume 26 (2008)
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Volume 25 (2007)
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Volume 24 (2006)
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Volume 23 (2005)
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Volume 22 (2004)
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Volume 21 (2003)
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Volume 20 (2002)
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Volume 19 (2001)
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Volume 18 (2000)
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Volume 17 (1999)
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Volume 16 (1998)
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Volume 15 (1997)
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Volume 14 (1996)
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Volume 13 (1995)
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Volume 12 (1994)
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Volume 11 (1993)
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Volume 10 (1992)
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Volume 9 (1991)
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Volume 8 (1990)
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Volume 7 (1989)
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Volume 6 (1988)
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Volume 5 (1987)
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Volume 4 (1986)
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Volume 3 (1985)
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Volume 2 (1984)
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Volume 1 (1983)