Valhall Field - Still on Plateau after 20 Years of Production

Barkved, O. I.; Heavey, Pete; Kjelstadli, Roar; Kleppan, Tore; Kristiansen, Tron Golder

doi:10.2118/83957-ms

Cited by 82 publications

(49 citation statements)

References 26 publications

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“…Cumulative production to date (March 2008) is 116 MMstb of 34.2 API oil and 166 Bscf of gas. For comparison, at Valhall a total of 500 MMstb of oil have been produced in the first 20 years (Barkved et al 2003). On the north shoulder of the anticline, post-depositional faults create a graben-like structure at the crest of the reservoir (Mackertich & Goulding 1999).…”

Section: Petroleum Geology and Reservoir Production Of South Arnementioning

confidence: 99%

Applying time-lapse seismic methods to reservoir management and field development planning at South Arne, Danish North Sea

Herwanger¹,

Schiøtt²,

Frederiksen³

et al. 2010

PGC

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At South Arne a highly repeatable time-lapse seismic survey (normalized root-mean-square error or NRMS of less than 0.1) allowed us to reliably monitor reservoir production processes during five years of reservoir depletion. Time-lapse AVO (amplitude v. offset) inversion and rock-physics analysis enables accurate monitoring of fluid pathways. On the crest of the field, water injection results in a heterogeneous sweep of the reservoir, whereby the majority of the injected water intrudes into a highly porous body. This is in contrast to a pre-existing reservoir simulation model predicting a homogeneous sweep. On the SW flank, time-lapse AVO inversion to changes in water saturation DS w reveals that the drainage pattern is fault controlled. Time-lapse seismic data furthermore explain the lack of production from the far end of a horizontal producer (as observed by production logging), by showing that the injected water does not result in the expected pressure support. On the highly porous crest of the reservoir compaction occurs. Time-lapse time shifts in the overburden are used as a measure for compaction and are compared with predictions of reservoir compaction from reservoir geomechanical modelling. In areas where compaction observations and predictions disagree, time-lapse seismic data give the necessary insight to validate, calibrate and update the reservoir geomechanical model. The information contained in time-lapse seismic data can only be fully extracted and used when the reservoir simulation model, the reservoir geomechanical model and the time-lapse seismic inversion models are co-visualized and available in the same software application with one set of coordinates. This allows for easy and reliable investigation of reservoir depletion and gives deeper insight than using reservoir simulation or time-lapse seismic individually.

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Section: Petroleum Geology and Reservoir Production Of South Arnementioning

confidence: 99%

Applying time-lapse seismic methods to reservoir management and field development planning at South Arne, Danish North Sea

Herwanger¹,

Schiøtt²,

Frederiksen³

et al. 2010

PGC

View full text Add to dashboard Cite

show abstract

“…They can also reactivate preexisting faults and fractures, create new fractures and deform the rock matrix. An extreme example of the latter effect is seen in the Valhall and Ekofisk fields offshore Norway (Agarwal et al 1997;Zoback & Zinke 2002;Barkved et al 2003;Toublanc et al 2005), where overpressured and undercompacted chalk underwent dramatic production-induced changes in porosity and, particularly, permeability. In such stress-sensitive reservoirs it can be difficult to distinguish matrix from fracture response.…”

Section: Stress-sensitive Reservoirs and Critically Stressed Faultsmentioning

confidence: 99%

Structurally complex reservoirs: an introduction

Jolley

Barr

Walsh

et al. 2007

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Structurally complex reservoirs form a distinct class of reservoir, in which fault arrays and fracture networks, in particular, exert an over-riding control on petroleum trapping and production behaviour. With modern exploration and production portfolios commonly held in geologically complex settings, there is an increasing technical challenge to find new prospects and to extract remaining hydrocarbons from these more structurally complex reservoirs. Improved analytical and modelling techniques will enhance our ability to locate connected hydrocarbon volumes and unswept sections of reservoir, and thus help optimize field development, production rates and ultimate recovery. This volume reviews our current understanding and ability to model the complex distribution and behaviour of fault and fracture networks, highlighting their fluid compartmentalizing effects and storage-transmissivity characteristics, and outlining approaches for predicting the dynamic fluid flow and geomechanical behaviour of structurally complex reservoirs. This introductory paper provides an overview of the research status on structurally complex reservoirs and aims to create a context for the collection of papers presented in this volume and, in doing so, an entry point for the reader into the subject. We have focused on the recent progress and outstanding issues in the areas of: (i) structural complexity and fault geometry; (ii) the detection and prediction of faults and fractures; (iii) the compartmentalizing effects of fault systems and complex siliciclastic reservoirs; and (iv) the critical controls that affect fractured reservoirs.Structurally complex reservoirs form a distinct class of reservoir in which fault arrays and fracture networks, in particular, exert an over-riding control on petroleum trapping and production behaviour

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“…The field was discovered in 1975 and brought on stream in 1982. A total of 500 MMSTB has been produced, with remaining 500 MMSTB to be produced (Barkved et al 2003). Structurally, Valhall field is a double plunging NNW-SSE trending inversion anticline.…”

Section: Valhall Fieldmentioning

confidence: 99%

“…The highly porous (>50%) and extremely soft chalk have resulted in rock compaction since the field began producing. Seabed subsidence (average rate of 50cm/yr) and well failures as the result of the rock compaction created large engineering challenges (Barkved, 2003). In additional compaction has also lead to dynamic reservoir properties, where initial fractures have closed upon pressure depletion while the new fractures may open.…”

Section: Valhall Fieldmentioning

confidence: 99%

Fracture detection from seismic P-wave azimuthal AVO analysis – application to Valhall LOFS data

Xia¹,

Thomsen²,

Barkved³

2006

In-Situ Rock Stress

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The P-wave reflection amplitude variation as a function of offset and azimuth reveals much about the anisotropic nature of the subsurface rocks. Stress in the fractured reservoir may be closely linked to the seismic anisotropy. We propose and implement a method that systematically examines the amplitude vs. offset and azimuth (AVOAz) behavior of CMP gathers to invert for the implied fracture orientations and density, without arbitrary procedures such as azimuthal sectoring. Standard statistical methods, applied in this context, give us confidence interval and acceptance criteria for our results. We applied the technique to the Valhall Life Of Field Seismic (LOFS) dataset and produced relevant attribute maps at the reservoir level. The results indicate a strong correlation with changes in stress state associated with production-induced compaction in a fractured reservoir.

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Valhall Field - Still on Plateau after 20 Years of Production

Cited by 82 publications

References 26 publications

Applying time-lapse seismic methods to reservoir management and field development planning at South Arne, Danish North Sea

Applying time-lapse seismic methods to reservoir management and field development planning at South Arne, Danish North Sea

Structurally complex reservoirs: an introduction

Fracture detection from seismic P-wave azimuthal AVO analysis – application to Valhall LOFS data

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