Geosciences

Form follows function. One of the common tasks of geoscientists is constructing a reservoir's morphology, its shape and configuration in relation to the larger tectionic fabric it is encased within.

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Victor Schmidt • Houston

Morphology

Form follows function. One of the common tasks of geoscientists is constructing a reservoir's morphology, its shape and configuration in relation to the larger tectionic fabric it is encased within. Acoustic methods work well for mapping horizons, and in some cases, for defining the gross morphology of reservoirs beneath the mapped horizons. Some of the most striking examples are the definition of channels using coherence techniques and 3D visualization advances that permit geobodies to be defined and analyzed individually.

But, for all the imaging power now available, acoustic methods cannot yet reveal the grain size distribution and porosity/permeability relationships within a reservoir. To get to this level for reservoir engineering and modeling, direct geological knowledge is needed. Well logs, sidewall cores, and whole cores are necessary to determine the porosity and permeability character of the reservoir.

Detailed study of these samples yields insight into the internal structures of the reservoir: bedding angles, sedimentation patterns, grain types, and distribution. But, these are only data points within the larger geobody and cannot provide full geobody morphology.

Point samples don't provide information on the mid-level morphology of structures that control production. To do this, a geoscientist must provide an engineer with a geologic model of the reservoir at the scale of production. A way must be developed to bridge the seismic scale (+/- 200 ft) and the well log scale (+/- 1 ft).

ExxonMobil Upstream Research has found such a link. John Van Wagoner and his colleagues at EMUR presented their findings at the American Association of Petroleum Geologists meeting earlier this year in a series of poster sessions. Van Wagoner's group has recognized a fundamental principle, the jet, that is active in all sediment transport systems and is scalable across all sizes of geologic structures. Because the principle is scalable, a new level of predictability is now available for geoscientists to begin bridging the scale gap among geophysical, geologic, and engineering tools. Sediment flute structures scale upward to point-mouth bars, which scale upward to deltaic structures.

Seismic stratigraphy and seismic attribute volumes are both attempts to delineate geobodies and their internal character. These techniques can only give a general answer about the reservoir character and are not specific enough for detailed reservoir modeling. The next step, possible with the EMUR work, is to backward-model the flow regimes that created the geobody. Knowing the flow states allows the rock data from logs and cores to be forward-modeled into a geobody's unique morphology. This detail model then identifies the best porosity and permeability trends in the geobody for optimal well placement, making the drilling and production cycle more efficient.

Total cluster

Total has purchased an SGI supercluster for its exploration and production department at its technical center in Pau, France. The 256-processor SGI Altix 3000 will be used for seismic processing applications, will complement the company's existing SGI infrastructure, and will be integrated into Total's storage area network environment.

The system uses 256 Intel Itanium 2 processors operating at 900 MHz with 1 TB of memory and 16 TB of disk storage. It provides processing power of close to 1 Tflops. The supercluster implements an optimized Linux environment capable scaling to 64 Itanium 2 processors on a single Linux node and to hundreds of processors in a cluster configuration.

EXPLORATION

North Sea Q-survey

WesternGeco has completed a contract from ChevronTexaco for a Q-marine 3D survey over the Captain field in the outer Moray Firth of the UK North Sea. The goal of the survey is to deliver a much clearer image of the field's internal architecture for new drilling targets and better oil recovery.

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The Geco Topaz collected over 200 sq km of Q-3D over the Captain field for ChevronTexaco.
Click here to enlarge image

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The Geco Topaz gathered the 30-day shoot covering block 13/22a in July, generating over 200 sq km of 3D seismic data.

TECHNOLOGY

SGI clusters

Silicon Graphics has unveil- ed a new workstation, the Tezro. The new system uses up to four 700-MHz RISC pro- cessors with 4 Mb of L2 cache, has 3.2 Gb/sec-band- width memory and input/output architecture, and can address up to 16 GB of memory. Advanced desktop visualization is available as well as dual-headed graphics.

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SGI's Tezro workstation has quad-processing power and memory.
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SGI also unveiled a new entry for the visualization market with its Voyager line of clustered-CPU computers. Scalable from two to 64 CPUs, SGI says the system is eight times smaller and one-fifth the price of similarly capable equipment. According to SGI, the system improves visualization processing 100 times by moving iso-surfacing computations to the graphical processing unit, which frees the central processor for other tasks.

Satellite communication

Telenor Satellite Services is covering new regions, including the coastal US, Caribbean, and coastal South America, with Ku-band satellite service. The service opens high-speed data communications, LAN and WAN connectivity, and Internet access via satellite for smaller vessels and offshore facilities. Service is available through Telenor's Santa Paula, California, US land earth station.

According to Pål Jensen, vice president of Sealink Services for Telenor Satellite Services, this is an inexpensive leased maritime solution for very small aperture terminals throughout the Americas.

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