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- Volume 33, Issue 6, 2015
First Break - Volume 33, Issue 6, 2015
Volume 33, Issue 6, 2015
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The Sleipner CO2 storage site: using a basin model to understand reservoir simulations of plume dynamics
Authors Andrew, J. Cavanagh, R. Stuart Haszeldine and Bamshad NazarianWhen simulating CO2 storage, an accurate match to the observed CO2 plume distribution is a prerequisite to establishing the dominant flow physics, and forecasting the storage site behaviour beyond the observed and expected injection period. The scale of industrial CO2 storage pilots such as Sleipner, offshore Norway, is similar to that of small hydrocarbon fields, and lends itself to reservoir simulation. However, the reservoir conditions and dynamics are significantly different: oil and gas production are dominated by imbibition, which is suited to multi-phase Darcy flow simulation; whereas CO2 storage represents the injection of a non-wetting fluid that displaces the in situ brine. The latter process is often termed ‘drainage’, and with respect to simulation, is more typical of regional basin modelling and percolating oil and gas migration. The challenge of modelling CO2 storage is to accurately represent this drainage displacement at the reservoir scale on short decadal timescales. The advantage is the detailed observational dataset with which such models are constrained. Using a Darcy flow model, the first decade of reservoir simulations for Sleipner has been characterized by poor matches to the known plume distribution, and forecasted plume dynamics that persisted for decades-to-centuries beyond the injection period. To overcome this problem of poor simulated replication, and to test the veracity of long term plume dynamics, we applied a basin model to Sleipner, which simulated the gravity-dominated migration of a buoyant fluid using a capillary percolation method. The basin model achieved an accurate match to the observed CO2 plume distribution. This suggests that simple Darcy-based reservoir simulation forecasts are misleading. The basin modelling insights allowed us to revisit the reservoir simulations, and, focusing on benchmark models of the uppermost layers, approximate the gravity-dominated regime of percolating flow. A pressure-compensated black oil reservoir simulation accurately matches the distribution and dynamics of the uppermost layers. The reservoir simulations also indicate that dissolution of CO2 will contribute significantly to storage within decades. While both approaches have their limitations, a combination of basin modelling and reservoir simulation provide perspectives that illuminate the dominant flow physics processes within the storage site, implying that the plume is in a state of dynamic equilibrium and likely to stabilize within years of the injection ending. Two challenges remain for the benchmark reservoir simulations: (A) how to represent the trapping and breaching behaviour of thin shale barriers for percolating CO2 within a storage formation; and (B) how to address pressure field artifacts in larger regional Darcy flow models of CO2 storage.
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The Western Mediterranean: established concepts and new insights
Authors Paolo Esestime and Richard WrigleyPaolo Esestime, Richard Wrigley and Neil Hodgson present a new interpretation of the Western Mediterranean Basin. The new insights connect the evolution of the onshore and the offshore areas, challenging the established basin model and the historic play concepts. Understanding the regional tectonic model of a basin is essential to provide the framework for the structural, sedimentary and thermal evolution, which are the basis for defining the petroleum system. The revisiting of accepted basin models is a good practice when new data becomes available from seismic campaign and drilling activity, allowing the interpretation to be finessed and more consistent with wells and geological data from the outcrops. The Western Mediterranean is a deep-water basin bounded by several orogens active since the Late Cretaceous-Paleocene, when the closure of the Tethys Ocean started (Stampfli et al., 2002; Golonka, 2014). The Paleogene-Neogene subduction and the collisional phases are responsible for the structural setting of the circum-Mediterranean orogens and the distribution of their allochthonous units, which are present in the mountain ranges (Figure 1).
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Noise suppression and multiple attenuation using full-azimuth angle domain imaging: case studies
Authors Aleksander Inozemtsev, Zvi Koren and Alexander GalkinThe EarthStudy 360 Imager is an advanced depth imaging system that first maps the full recorded seismic data into the subsurface grid points and then decomposes the data into local angle domain (LAD) bins. It is based on specially designed diffraction operators using bottom-up ray tracing. In this article, we focus on the ability of the EarthStudy 360 Imager to attenuate different types of wave characteristics considered as both random and coherent noise – in particular, different orders of multiples, and non-reflection seismic events such as Rayleigh, refraction, diffraction and ‘side’ waves. The method is based on internal implementation of local slant stack (LSS) operators optimally designed for each primary ray pair associated with a given source-image point-receiver path and the corresponding seismic data event. The LSS is applied in the direction of the horizontal slowness components of the arriving rays at the acquisition surface, where the size of the LSS (the number of traces involved) is computed independently for each ray pair from its first Fresnel zone. Thus, primary reflection events sharing the same traveltime and the same surface directivity as the traced ray pairs are emphasized (highly weighted), while all other events (considered as noise) are simultaneously attenuated. We demonstrate our method in four different land data examples with different levels of geological complexities.
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How reservoir uncertainty and sensitivity studies can lead to better field development and hardware decisions
Authors Garret, M. Leahy and Lifang WangGarrett M. Leahy and Lifang Wang propose a new approach to reducing uncertainties in key production metrics that brings risk management back to the centre of the decision-making framework. Running producing oilfields is a complex business. Production managers need to balance the evolution of production from dynamic and geologic changes with ageing fields and infrastructure and the failure of facilities and hardware. However, optimizing production is in itself a complex task as there are many variables and levers that reservoir engineers need to access. Injection rates, fluids, and production chokes can all influence day-to-day operations at the wellhead and ultimately the long-term productivity (and value) of the reservoir. Not all of these levers are created equally: the day-to-day management of well chokes to optimize flow, for example, can be significantly less risky (and costly) than a new injection or enhanced oil recovery programme. Rather than simply jumping on the big-data, ‘pervasive sensing’ bandwagon to solve this problem, we propose a more strategic approach that brings risk management back to the centre of the decision-making framework. Conventional wisdom has been that making measurements of key flow parameters (water cut, flow rate, temperature, downhole pressure, etc) is the key to accurate production forecasting. For example, how much water and sand is being produced and from which wells? What impact does this have on processing facilities and hardware choices? How can threats to production caused by water breakthrough, corrosion, erosion and hydrates, be pre-empted?
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European Research Council funds 2D ultra-deep seismic reflection data acquisition across the Atlantic Ocean
By Satish SinghProfessor Satish Singh of the Institut de Physique du Globe de Paris (IPGP) reports on a European Research Council (ERC) funded project to study the oceanic lithosphere down to its base at up to 100 km depth.
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Young geoscientists show the way forward with style in student paper competition
The brightest geoscience students competed for the best student submission to the EAGE Annual Meeting 2015. Competition was fierce, but after much deliberation three papers have been chosen to be presented as part of the EAGE Technical Programme in Madrid.
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Equipment QC approaches in land seismic acquisition
By Steve WilcoxSteve Wilcox analyses the capabilities of the most popular land acquisition systems available today in terms of their ability to provide the observer with QC data. Since the introduction around 2003 of the first modern wireless land acquisition systems (see Panel 1), the market has seen a variety of different systems introduced with a blend of different features. Over the same time, the land seismic market in North America has also undergone a remarkable transformation, whereby the traditional telemetry cable-based systems have lost their dominant position, having been overhauled by the combination of various wireless solutions. In traditional cabled systems, the observer had a clear view of his task controlling the operation of the system. The status of the entire system was available to him in real-time, with QC data being transmitted from the field equipment via telemetry cable. He could see the condition of the batteries, and direct the crew to replace them as required; he could see with a high degree of confidence what wind or environmental noise the sensors were picking up; and above all he could immediately detect if sensors were out of specification or cables were damaged. Thus, he had all the information necessary to acquire good quality seismic data. The Achilles’ heel of the operations, of course, was the susceptibility of the telemetry cables to damage during operations and an alternative to these was long sought. The introduction of wireless systems removed the issues around cable-damage, and their success – reflected in their increasing dominance in the North American market – clearly shows that seismic contractors using them experience operational benefits in doing so. Figure 1 gives an illustration of the change in relative market share from 2007 to 2011, and indications are that wireless systems have further increased their market share since. There are, however, a number of differences in the capabilities of the different systems available, most especially regarding their provision of QC data to the system observer. Additionally, some systems have been developed to offer some of the advantages of both cabled and wireless systems, and it is the intention in this paper to address systems according to their capabilities rather than their data transmission medium.
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Performance analysis of forward-looking GPR ultra-wideband antennas for buried object detection
Authors Kyle A. Gallagher, Brian R. Phelan, Kelly D. Sherbondy and Ram M. NarayananWe are currently developing a Stepped-Frequency Radar (SFR) which utilizes a custom-made uniform linear array of 16 Vivaldi notch receive antennas and two Transverse Electromagnetic (TEM) horn transmit antennas. The SFR has an operating band of 300–2000 MHz, and a minimum frequency step-size of 1 MHz. The custom-made TEM horn antennas are used for the transmission of the SFR’s ultra-wideband (UWB) spectrum. This paper discusses a comparison analysis between a commercially available UWB antenna and the currently used TEM horns. Gain, Voltage Standing Wave Ratio (VSWR), and antenna pattern measurements for each antenna are presented. The antennas were also tested for their ability to detect buried targets in a simple stepped-frequency radar system using a network analyser as a transmitter and receiver. An analysis of the gain, VSWR, beamwidth, and measured data from radar test of each antenna was performed, providing insights into each antenna’s performance on the SFR’s ability to detect buried targets. The information provided in this paper will be useful to the radar community in exploring developmental standoff detection solutions for military applications such as obscured target detection of obstacles and explosive hazards.
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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)