4D Seismic in Brazil: Experiences in Reservoir Monitoring

Johann, Paulo; Thedy, E.A.; Gomes, Frederico Aguiar Ferreira; Schinelli, Marco

doi:10.4043/18400-ms

Cited by 16 publications

(5 citation statements)

References 8 publications

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“…The seismic volumes used were: • a 1997 acquisition, with azimuth 123° and good resolution, but very noisy (Johann et al, 2006;Johann et al, 2009); • a 2010 acquisition that has not yet been mentioned in previous articles.…”

Section: Methodsmentioning

confidence: 99%

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Integration of geophysical and geomechanical data to understand the depletion of the Marlim field, Campos Basin

Torres

Barroso

2021

Geol. USP. Sér. Cient.

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Located in the Campos Basin, Brazil, the Marlim field, consists of two turbidite systems deposited during eustatic sea-level variations in the Oligocene/Miocene. The reservoir was discovered in 1985, and its production started to decline in 2002. One of the techniques selected to assist in the recovery of oil from the reservoir was the 4D seismic. However, its interpretation can be complex. In order to help address this issue, the present study proposed an analysis of the depletion of a small field area from 1997 to 2010, combining geophysical (4D seismic) and geomechanical (pore pressure) data through the construction of pore pressure 3D models for both years, which can be subtracted and compared to seismic anomalies. The results obtained were: an average depletion of 0.42 ppg (50.33 kg/m3) of pore pressure gradient in the field; the identification of potential fluid-flow barriers, such as an NW-SE-oriented channel and sealing faults; and the detection of two areas with an expressive presence of 4D seismic anomalies, one of them showing a quite evident difference between pore pressure gradients, suggesting field depletion. The use of very old and noisy seismic data hindered the application of this methodology. Nevertheless, this research demonstrated the relevance of estimating pore pressure in the reservoir and how this geomechanical parameter can be useful in assessing the level of field depletion.

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Section: Methodsmentioning

confidence: 99%

“…Modified from Pinto et al (2001) and Oliveira et al (2007). and with excellent porosity (Lorenzatto et al, 2004;Johann et al, 2006;Oliveira, 2008).…”

Section: Introductionmentioning

confidence: 99%

Integration of geophysical and geomechanical data to understand the depletion of the Marlim field, Campos Basin

Torres

Barroso

2021

Geol. USP. Sér. Cient.

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“…Similarly, hydrophones (and possibly accelerometers) are towed behind a boat inside a so-called streamer cable or geophones (combined with hydrophones) can be laid directly on the seafloor for marine acquisition; whilst geophones are used for land acquisition. After the introduction of 3D seismic [11], today's conventional seismic acquisition campaigns may last several weeks up to a few months [7,26,10]. In an attempt to improve acquisition efficiency, and therefore limit the time, cost, and associated environmental impact, [6,9,3,36] introduced a new paradigm in seismic acquisition usually referred to as simultaneous shooting.…”

Section: Introductionmentioning

confidence: 99%

A hybrid approach to seismic deblending: when physics meets self-supervision

Luiken¹,

Ravasi²,

Birnie³

2022

Preprint

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To limit the time, cost, and environmental impact associated with the acquisition of seismic data, in recent decades considerable effort has been put into so-called simultaneous shooting acquisitions, where seismic sources are fired at short time intervals between each other. As a consequence, waves originating from consecutive shots are entangled within the seismic recordings, yielding so-called blended data. For processing and imaging purposes, the data generated by each individual shot must be retrieved. This process, called deblending, is achieved by solving an inverse problem which is heavily underdetermined. Conventional approaches rely on transformations that render the blending noise into burst-like noise, whilst preserving the signal of interest. Compressed sensing type regularization is then applied, where sparsity in some domain is assumed for the signal of interest. The domain of choice depends on the geometry of the acquisition and the properties of seismic data within the chosen domain. In this work, we introduce a new concept that consists of embedding a self-supervised denoising network into the Plug-and-Play (PnP) framework. A novel network is introduced whose design extends the blind-spot network architecture of [28] for partially coherent noise (i.e., correlated in time). The network is then trained directly on the noisy input data at each step of the PnP algorithm. By leveraging both the underlying physics of the problem and the great denoising capabilities of our blind-spot network, the proposed algorithm is shown to outperform an industry-standard method whilst being comparable in terms of computational cost. Moreover, being independent on the acquisition geometry, our method can be easily applied to both marine and land data without any significant modification.Preprint. Under review.

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“…The application of 4D technology in Brazil begun around 22 years ago, although there was a strong commitment of the geophysicists with production seismic monitoring even some years before (Johann et al, 2006). Recently the interest in combining geophysics and geomechanics in 4D seismic studies has increased.…”

Section: Introductionmentioning

confidence: 99%

Velocity-strain relations from hydrostatic measurements on multiple lithologies

2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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We investigate the velocity-strain sensitivity on numerous samples from the entire stratigraphic column in the Santos and Campos basins, Offshore Brazil. The samples all measure P-wave velocity as a function of applied effective pressure during hydrostatic loading. We introduce a transform to derive the sensitivity of vertical P-wave velocity to vertical strain, from the observed velocityeffective stress relationship. This allows to calculation of 𝑅 −factors, a common parameter to integrated 4D seismic and 4D geomechanical data, from the velocity measurements. The non-linearity in the relationship between P-wave velocity and applied effective stress causes a non-linearity in 𝑅 −factor as a function of initial stress state at which the 𝑅 −factor is evaluated. This naturally explains a depth dependence of 𝑅 −factor in field data. The derived 𝑅 −factor from laboratory data are found to be an order of magnitude larger than those derived from field observations. This is an effect which is commonly observed, and which to date has not been satisfactorily explained. We propose that the relative magnitudes of 𝑅 −factors between different lithologies are a useful diagnostic. We find that shales, marls and pre-salt carbonates have an increased 𝑅 −factor by a factor of approximately four compared to unconsolidated sandstones.Conversely, evaporites (halites and unhydrites) show low 𝑅 −factors of approximately 0.5 of those observed in unconsolidated sandstones.

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4D Seismic in Brazil: Experiences in Reservoir Monitoring

Cited by 16 publications

References 8 publications

Integration of geophysical and geomechanical data to understand the depletion of the Marlim field, Campos Basin

Integration of geophysical and geomechanical data to understand the depletion of the Marlim field, Campos Basin

A hybrid approach to seismic deblending: when physics meets self-supervision

Velocity-strain relations from hydrostatic measurements on multiple lithologies

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