There are about 330 000 wells in western Canada, almost all of which have wireline logs in the public domain. These have previously been available as either hardcopy prints or microfiche, but what has changed recently is the arrival of the depth-registered raster log image.

This hybrid technology - mid way between dumb images and digital logs offers a significant business benefit. The image effectively captures all the information on the original log, with none of the risks involved in digitizing or vectorizing. Depth registration also allows log intervals to be called up from the database intelligently.

Calgary's fiber network infrastructure contributes to the success of this technology with the image stored on a central server, allowing the customer to retrieve the log from the workstation. Logs can also be delivered on CD or DVD.

The main vendors are : QC Data - delivery of images is via the Accumap application and their "Accumap Opportunity Network" (exclusive fiber connection), International Datashare Corporation - with delivery over one of three competing fiber networks and MJ Systems - images from their fiche library, delivered on CD or DVD. (MJ Systems is now collaborating with geoLogic - see last month's PDM)

The big advantages of raster log images are:

1. Every log on every well is "instantly" available (not just the usual suite).

2. There is no interpretation or error in the process of capturing the log image and no worries about smoothing, splicing errors or the wrong sample rate.

The drawbacks:

1. limited applications (so far) to support interpretation using these images

2. the images are raster, not vector. So you can't do cross-plots, petrophysical computations, rescaling, stretch/shrink, etc.

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