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- Volume 37, Issue 10, 2019
First Break - Volume 37, Issue 10, 2019
Volume 37, Issue 10, 2019
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Assessing soil amplifications in Groningen, the Netherlands
Authors Janneke van Ginkel, Elmer Ruigrok and Rien HerberAbstractSince the shallow part of the Dutch subsurface is practically always unconsolidated, the elastic waves generated by deeper (~3000 m) seated earthquakes will be subjected to transformation when arriving in these layers. Since, the number of induced seismic events has increased over recent decades, a better understanding of site response of the Dutch subsurface is required. Local site amplification can directly be measured due to the presence of sensors at multiple depth levels in the Groningen borehole network. Amplification factors from 73 local events have been calculated for each borehole location to quantify earthquake site response. Furthermore, horizontal-to-vertical spectral ratios (HVSR) from the ambient seismic field are calculated.
A relationship has been established between the composition of the upper Holocene sediments and the size of the amplitudes of HVSR and earthquake site response. Highest amplitudes are measured where the Holocene sediments are composed of clay, fine sands, silts and peat. We can conclude that HVSR from the ambient seismic field can be used as a first-order proxy to get an indication for wave amplification during a seismic event. This allows a first assessment on wave amplification at sites without sensors at multiple depth levels and without abundant local seismicity.
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FWI as an effective solution for land near-surface model building into the area with complex geological settings: Eastern Siberia case study
Authors D. Tverdokhlebov, V. Korobkin, A. Kleshnin, E. Kashirina, E. Danko, V. Zaravnyaev and R. MelnikovAbstractSeismic imaging in the Eastern Siberia region is challenging due to the presence of complex overburden anomalies such as magmatic intrusions and thrusts in the suprasalt complex leading to significant vertical and lateral property variations of high-velocity halite-carbonate geological sections with multiple velocity inversions, complex shallow stratigraphy and substantial topography. Such geological settings create amplitude dimming and wipeouts in the images and cause structural distortions at the reservoir level.
We applied full-waveform inversion (FWI) technology to overcome limitations of the conventional workflow and to support the exploration programme. The primary output of FWI is a high-resolution subsurface velocity model, which can be used as an attribute to improve interpretation of the overburden sediments, to identify shallow hazards, to derisk exploration prospects and to optimize well placement.
We tested FWI on a conventional 3D land data set to create a near-surface velocity model. Detailed subsurface models generated with FWI provided an accurate description of the overburden and helped us to investigate shallow geological environments. Predrill predictions using the FWI velocity volume showed excellent agreement with well measurements and made it possible to recommend the technology for inclusion in the processing flow.
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Reducing drilling risk on Culzean using WAVI-VSP
Authors Rachel Jones, John Banks, Howard Simpson, Nick Randall and Antoine ParéAbstractThe Culzean field is an ultra-High Pressure, High Temperature (uHPHT) gas-condensate field located in block 22/25a of the UK sector, Central North Sea (Figure 1). The primary reservoir is Triassic and combined with a secondary reservoir in the Jurassic (Figure 2). Total recoverable resources are estimated to be between 250 and 300 MMBOE.
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The decision-oriented world: effective management of uncertainty in geomodelling workflows
Authors Lucy MacGregor, Michael Stewart, Keegan Benallack and Luke JohnsonAbstractGiven a realistic set of sub-surface data, the number of plausible geological models that can be constructed can run into the millions or tens of millions. It is therefore impractical for a geologist to examine the entire space of possible models and thereby correctly characterize uncertainty. Commonly applied approaches to this problem use simplifications such as experimental design, parameter sensitivity analysis or Monte Carlo simulation to attempt to reasonably account for input uncertainty while balancing computational expenditure and time. Broadly, this is undertaken by assessing which model inputs (for example porosity or permeability) have the most significant impact on response variables of choice, typically volume based or commercial metrics such as net present value (NPV) or estimated ultimate recovery (EUR). Specific parameters are then perturbed to produce an assumed representative subset (in many cases a low, mid and high case) of the range of possible models (see for example Pyrcz and Deutsch, 2014).
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Increasing confidence in estimating stimulated reservoir volume by integrating RTA and microseismic analysis
Authors Peyman Moradi, Katie Jeziorski and Doug AngusAbstractRate Transient Analysis (RTA) and microseismic monitoring are gaining momentum in modelling Stimulated Reservoir Volume (SRV) in Multi-Frac Horizontal Wells (MFHWs) in unconventional reservoirs. From a behavioural perspective, RTA uses history matching and production data analysis to estimate fracture volume and productivity, and microseismic analysis maps frack-ing-induced micro-earthquakes to calibrate the fracture network from a spatiotemporal point of view. Defining the concepts of normalized rate, material balance time and pseudo-time, dynamic drainage volume, together with convolution, deconvolution and analytical models, make RTA a powerful and computationally efficient tool for modelling MFHWs (Blasingame et al., 1991; Agarwal et al., 1998, Mattar and Anderson, 2003). Poe (2005) proposed a rate-transient analysis method for evaluating the performance of wells with limited pressure data using the superposition theory and dimensionless parameters. Soliman and Adams (2010) estimated fracture properties by applying Flow Regime Identification (FRI) plots to early production data, followed by using analytical models derived for each distinct flow regime. Kuchuk et al. (2016) calibrated reservoir models by history-matching the transient flow rate and pressure measurements. Brown (2009), Stalgorova and Mattar (2012a, 2012b), Deng et al. (2015), and Yuan et al. (2015) divided the reservoir into a series of linear flow regions and derived analytical pressure transient models from the pressure diffusion equation, not only to confirm the validity of the identification, characterization and diagnostic analyses but also to provide production forecasts and carry out optimization studies. Clarkson et al. (2015) successfully applied RTA analytical and semi-analytical modelling techniques to a gas condensate MFHW in a Western Canadian Basin, highlighting the fact that building a predictive understanding of drainage volume dynamics is best started with physics-based analytical models rather than multi-phase numerical simulations. This is particularly important in unconventional reservoirs where the complex, small-scale physics and rock-fluid interactions significantly hinder gathering enough measurements to support the numerically added complexities.
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Integrated sedimentological and seismic reservoir characterization studies as inputs into a Lower Cretaceous reservoir geomodel, offshore Abu Dhabi
AbstractReservoir characterization plays a fundamental part in the development and/or appraisal of any hydrocarbon field. Understanding and quantifying the characteristics and distribution of the reservoir rock properties is an evaluation step that needs to be performed before starting any reservoir model. An accurate description of the reservoir is vital to help appropriately manage and optimize oil recovery. From core to seismic scale, any relevant piece of information should be integrated in order to reduce uncertainties, and optimize understanding of the final flow behaviour and fluid distribution inside the reservoir. The goal of the final geomodel is to obtain consistent properties that are driven by the geological facies models (including depositional facies and diagenesis; reservoir rock types) and trended by the seismic information.
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Horizontal infill well with AICDs improves production in a mature field — a case study
Authors Ilhami Giden, Michael Nirtl, Hans Thomas Maier and Ismarullizam Mohd IsmailAbstractMatzen is a super-mature oilfield operated by OMV Austria E&P GmbH and is located approximately 25 km northeast of Vienna, Austria. It is one of the largest onshore oilfields in Europe and consists of several stacked reservoirs. The 16th Tortonian horizon (16.TH) is the biggest reservoir in this field. The Bockfliess area is the westernmost part and covers approximately 3.7 × 3.6 km. Seventy seven wells are currently active, of which 62 are production and 15 are injection wells (Figure 1).
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Improved seismic images through full-azimuth depth migration: updating the seismic geological model of an oil field in the pre-neogene base of the Pannonian Basin
AbstractA seismic survey was conducted in a production oilfield located in Serbia, confined to the Pre-Neogene (Paleozoic) base of the Pannonian basin. It was assumed that additional significant unrecovered residual reserves still exist in this oil field, as well as additional similar undiscovered reservoirs. The further characterization of the existing reservoirs, and the identification and characterization of the new ones, required the implementation of advanced seismic imaging technology. Hence, a new project was designed composed of the following steps: Obtaining the highest possible seismic resolution in the area, and creating an updated, high-definition subsurface model that includes the structural complexities of the geological layers and the azimuthal anisotropic effects (e.g., fracture systems), especially within the target layers. This enables the identification and characterization of the target productive zones, making it possible to accurately design and plan the well placement.
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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)