Gas-Oil Contact Monitoring at Troll Using High Resolution 4D Analysis and Neural Networks

Bertrand, A.; McQuaid, Sean; Bobolecki, Roman; Leiknes, S.; Ro, Hans Egil

doi:10.3997/2214-4609-pdb.1.c040

Cited by 3 publications

(1 citation statement)

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“…For example, in the Nelson field, the oil–water contact moved vertically by 30–60 m after 10 years of production (MacBeth, Stephen and McInally ) and in the Troll field, the gas–oil contact moved by 10–12 m after 5 years of production (Bertrand et al . ). Another example is in a chalk field where the gas–water contact is interpreted to have moved by 25 m in 4 years (Barker et al .…”

Section: Seismic Acquisition Versus Production Time‐scalesmentioning

confidence: 97%

Intra‐survey reservoir fluctuations – implications for quantitative 4D seismic analysis

Omofoma

MacBeth

Amini

2018

Geophysical Prospecting

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A B S T R A C TDuring the time taken for seismic data to be acquired, reservoir pressure may fluctuate as a consequence of field production and operational procedures and fluid fronts may move significantly. These variations prevent accurate quantitative measurement of the reservoir change using 4D seismic data. Modelling studies on the Norne field simulation model using acquisition data from ocean-bottom seismometer and towed streamer systems indicate that the pre-stack intra-survey reservoir fluctuations are important and cannot be neglected. Similarly, the time-lapse seismic image in the post-stack domain does not represent a difference between two states of the reservoir at a unique base and monitor time, but is a mixed version of reality that depends on the sequence and timing of seismic shooting. The outcome is a lack of accuracy in the measurement of reservoir changes using the resulting processed and stacked 4D seismic data. Even for perfect spatial repeatability between surveys, a spatially variant noise floor is still anticipated to remain. For our particular North Sea acquisition data, we find that towed streamer data are more affected than the ocean-bottom seismometer data. We think that this may be typical for towed streamers due to their restricted aperture compared to ocean-bottom seismometer acquisitions, even for a favourable time sequence of shooting and spatial repeatability. Importantly, the pressure signals on the near and far offset stacks commonly used in quantitative 4D seismic inversion are found to be inconsistent due to the acquisition timestamp. Saturation changes at the boundaries of fluid fronts appear to show a similar inconsistency across sub-stacks. We recommend that 4D data are shot in a consistent manner to optimize aerial time coverage, and that additionally, the timestamp of the acquisition should be used to optimize pre-stack quantitative reservoir analysis.

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Section: Seismic Acquisition Versus Production Time‐scalesmentioning

confidence: 97%

Intra‐survey reservoir fluctuations – implications for quantitative 4D seismic analysis

Omofoma

MacBeth

Amini

2018

Geophysical Prospecting

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Using complex seismic attributes to improve 4D visibility of fluids contact movement

Schinelli

2006

SEG Technical Program Expanded Abstracts 2006

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Advanced Wells: A Comprehensive Approach to the Selection Between Passive and Active Inflow-Control Completions

Al-Khelaiwi¹,

Birchenko²,

Konopczynski

et al. 2010

SPE Production &Amp; Operations

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Summary Well architecture advances from conventional wells to horizontal. Then multilateral wells, which have maximized reservoir contact, have been paralleled by advances in completion-equipment development. Passive inflow-control devices (ICDs) and active intervalcontrol valves (ICVs) provide a range of fluid-flow control options that can enhance the reservoir sweep efficiency and increase reserves. ICVs were used originally for controlled, commingled production from multiple reservoirs, while ICDs were developed to counteract the horizontal well's heel/toe effect. The variety of their applications has proliferated since these beginnings. Their application areas now overlap, resulting in it becoming a complex, time-consuming process to select between ICVs or ICDs for a particular well's completion. This publication summarizes the results of a comprehensive, comparative study of the functionality and applicability of the two technologies. It maps out a workflow of the selection process on the basis of the thorough analysis of the ICD and ICV advantages in major reservoir, production, operation, and economic areas. It provides detailed analysis of Reservoir-engineering aspects, such as uncertainty management, formation heterogeneity, and the level of flexibility required by the developmentProduction and completion characteristics, such as tubing size, the number of separately controllable zones, the completion of multiple laterals, and the value of real-time informationOperational and economical aspects, such as proper modeling, gas-and oilfield applications, equipment costs and installation risks, long-term reliability, and technical performance. The results of this work's systematic approach form the basis of a screening tool to identify the most appropriate control technology for a wide range of situations. This selection framework can be applied by both production technologists and reservoir engineers when choosing between passive or active flow control in advanced wells. The value of these guidelines is illustrated by their application to synthetic- and real-field case studies.

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Gas-Oil Contact Monitoring at Troll Using High Resolution 4D Analysis and Neural Networks

Cited by 3 publications

References 0 publications

Intra‐survey reservoir fluctuations – implications for quantitative 4D seismic analysis

Intra‐survey reservoir fluctuations – implications for quantitative 4D seismic analysis

Using complex seismic attributes to improve 4D visibility of fluids contact movement

Advanced Wells: A Comprehensive Approach to the Selection Between Passive and Active Inflow-Control Completions

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