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Title: 3D Modeling of a deepwater EM exploration survey

Authors:
; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE
OSTI Identifier:
926570
Report Number(s):
LBNL-60837
R&D Project: G3W091
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geophysics; Journal Volume: 71; Journal Issue: 5; Related Information: Journal Publication Date: 2006
Country of Publication:
United States
Language:
English
Subject:
58

Citation Formats

Hoversten, G. Michael, Newman, Gregory A., Geier, Nathan, and Flanagan, Guy. 3D Modeling of a deepwater EM exploration survey. United States: N. p., 2006. Web. doi:10.1190/1.2240113.
Hoversten, G. Michael, Newman, Gregory A., Geier, Nathan, & Flanagan, Guy. 3D Modeling of a deepwater EM exploration survey. United States. doi:10.1190/1.2240113.
Hoversten, G. Michael, Newman, Gregory A., Geier, Nathan, and Flanagan, Guy. Tue . "3D Modeling of a deepwater EM exploration survey". United States. doi:10.1190/1.2240113.
@article{osti_926570,
title = {3D Modeling of a deepwater EM exploration survey},
author = {Hoversten, G. Michael and Newman, Gregory A. and Geier, Nathan and Flanagan, Guy},
abstractNote = {},
doi = {10.1190/1.2240113},
journal = {Geophysics},
number = 5,
volume = 71,
place = {United States},
year = {Tue Jan 10 00:00:00 EST 2006},
month = {Tue Jan 10 00:00:00 EST 2006}
}
  • Allied Energy and the Statoil and BP Alliance are currently partners in the OPL 210 license, in deepwater Nigeria. The license has a 5 year initial exploration phase which carries a two well commitment. To optimize the location of these wells in this challenging and costly drilling environment the partnership has decided to acquire extensive exploration 3D seismic data within the block. Interpretation of the first of two planned 3D surveys has led to a much clearer understanding of: (a) The structural segmentation of the prospect and thus a clearer idea of the likely hydrocarbon pool size. (b) The distributionmore » of amplitude anomalies and thus, hopefully, a superior understanding of reservoir distribution and hydrocarbons. Here the limiting factor is clearly the lack of deepwater geophysical calibration, due to the absence of wells. Consequently, conclusions at this stage, are qualitative either than quantative. Combined with detailed seismic stratigraphic and high tech geophysical analysis, these two aspects will assist in the highgrading of segments in the prospect, prior to final decisions on the well locations. The first well, planned for 1995, will be one of the first wells drilled in the Nigerian deepwater area. Examples of both 2D and 3D data will be used to demonstrate the above and some of the first well results will be integrated into our interpretation to highlight how some of our perceptions may have changed.« less
  • OPL 210 lies in deepwater on the northwestern flank of the Niger Delta. The partners in this block are Allied Energy and The Statoil and BP Alliance. The license has a 5 year initial exploration phase and carries a 2 well commitment. At present the database comprises a 1 x 1 km grid of 2D seismic across the block, and 450 sq. km of 3D in an area of special interest. A larger 3D survey is planned for 1995. Little is known about the reservoir in the deep water, but we expect our main target to be ponded slope andmore » basin turbidites. As such the bulk of the shelf well data available has little or no relevance to the play type likely to be encountered. Prior to drilling, seismic stratigraphy has been one of several methods used to generate a consistent predictive reservoir model. The excellent quality and high resolution of the 3D data have allowed identification and detailed description of several distinctive seismic facies. These facies are described in terms of their internal geometries and stacking patterns. The geometries are then interpreted based on a knowledge of depositional processes from analog slope settings. This enables a predictive model to be constructed for the distribution of reservoir within the observed facies. These predictions will be tested by one of the first wells drilled in the Nigerian deepwater in mid 1995.« less
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  • The importance of deepwater drilling to future reserve additions is illustrated by a prediction by Shell Oil Co. For every barrel of oil that will be found on land in the future, 2 will be found off shore, and one of those will be in deep water. One-half of the world's proven reserves of oil lie off shore, but only one-quarter of those are easily accessible in less than 650 ft of water. Twenty percent of the world's oil production and over 5% of its natural gas currently come from offshore fields. Even though a large capital investment is requiredmore » to find and develop deepwater reserves, it is necessary for the Petroleum Industry to venture into deeper water and remote and hostile areas. In industry terms, offshore operations are still relatively new, and despite 30 yr of experience, the frontiers are constantly being extended.« less
  • For SPECT reconstruction, iterative Maximum Likelihood Expectation Maximization (ML-EM) estimation has a huge computational burden. The objective of this paper is to compare images obtained by ML-EM and an EM algorithm acting on Ordered Subsets of projections (OS-EM). Two digital phantoms, a cylinder with two cold spots and an ellipsoid with several hot spots and one cold spot were reconstructed from 120 simulated noisy projections. 1D ({delta}-like point source response), 2D (single slice response) and fully 3D reconstruction were investigated. Three quantities were calculated for the evaluation, viz. contrast, normalized standard deviation and mean squared error. In the case ofmore » fully 3D reconstruction, OS-EM 60 reconstructions (i.e., using 60 ordered subsets) were very close to ML-EM reconstructions. This shows that the OS-EM algorithm is an extremely fast and efficient method to accelerate iterative SPECT reconstruction with speed-up factors of close to half the number of projections.« less