The Ohio Department of Natural Resources (ODNR), Division of Geological Survey (DGS) recently initiated a program to digitally scan paper copies of geophysical logs using a scanning device designed specifically for this application. While it is not possible, as yet, to scan all of the geophysical logs in the division's collection (approximately 70,000 suites of logs), the division has been scanning all of the logs submitted to it each year beginning with 2002 submissions. As funding for scanning of archival records becomes available, the division will contract services for scanning those logs received prior to 2002.
 
The microfilm reader-printers that the Survey had used for many years to view and print geophysical logs are no longer operable. The reader-printers are no longer manufactured, and repair parts are no longer available for them. Further, the silver-coated copy paper used by these machines is no longer available. Thus, the division's only means for log reproduction for the last couple years has been page-by-page duplication on a standard office copier. This process is both costly and time-consuming for our customers and yields copies that must be taped together. Digital scanning will enable the division to: 1) modernize its archival system for geophysical logs, 2) reduce labor-intensive manual copying operations, and 3) effectively respond to increasing oil-and-gas-industry requests for digital log copies.
 
Geophysical logs can be converted to digital form in two basic formats-vector and raster. The most common file format used for vector digital logs is the Log ASCII Standard (LAS). This is simply a text file in a specific layout that stores all the standard information from a well log including header information such as operator, location, total depth (TD), etc., and it also stores the numeric value of each well-log curve along with the depth information at half-foot increments (figure 1). Specialized log-analysis software can read these files, recreate the actual log curves, and perform detailed analyses of the data (e.g., cross-plots, porosity calculations, shale volume, etc.). It is a very time-consuming process to convert a paper log to a digital vector log file. Specialized software is required, and each individual curve must be digitized (i.e., trace the log curve with the cursor on the computer). Even with the newest conversion software, the time required to create an LAS file of a well log can range from 45 minutes to more than 2 hours. Thus, it is time prohibitive to convert the state's entire geophysical log library to vector format in the near-term. The DGS has, however, converted logs of more than 200 of the deepest wells in the state to LAS format. These files can be downloaded by clicking here or purchased on CD-ROM. The advantages of vector logs are the small file size (range from less than 100 kilobytes to about 2 megabytes) and, of course, the great versatility of use and analysis capability that one has with the files.
 
Raster-format digital logs are simply images of the logs from a scanner, usually stored in TIF format (figure 2). However, many software companies have created applications that will allow the use of raster logs for the automatic or semi-automatic creation of cross-sections, and other types of custom displays. It is fairly easy to create a raster log file using a specialized scanner designed for this purpose. It is similar to running the log through an auto-feed offi ce copier. However, the files are very large compared to vector (LAS) files. Raster log files range in size from about 500 kilobytes for a shallow well to as much as 80 megabytes for a deep well with color. Thus, the cost of storing and backing-up large collections in this format is large. The resultant image quality is also dependent on the quality of the original image. If the paper copy of the log is dark, washed out, or smudged, these same deficiencies will be evident in the resultant digital image.
 
As stated, the DGS is now scanning all geophysical logs submitted to it beginning with 2002 submittals. In addition, the DGS has scanned numerous other logs used in DGS geological studies. Through these efforts, the raster log collection already includes about 8,000 logs (for 3800+ wells) and is increasing daily. The DGS will continue to seek funding opportunities from various sources for scanning of all of the logs in its collection. In the meantime, a spreadsheet (xls file) containing a list of available digital logs is available by clicking here. Customers can view the list and choose which digital logs they would like to order from the division's Geologic Records Center.
 
The cost of digital (TIF) log files, and of paper prints created from the digital log files, are as follows:
 

Digital files on CD $2.00 per log; $20 minimum order Paper prints of scanned logs $4.00 for entire well with TD less than 4,000 feet $6.00 for entire well with TD between 4,000 and 6,000 feet $8.00 for entire well with TD greater than 6,000 feet

 
This pricing schedule is based on projected sales volume of digital logs based on previous sales of paper log copies, and the cost to maintain and replace records management/duplication equipment. The cost of paper prints of scanned logs is much less (on a per log basis) than current charges for logs duplicated on an office copier. Digital log files are significantly less costly (on a per log basis) than printed copies and provide the customer with a product that has many more potential uses than a paper copy.
 
Questions concerning this project should be directed to Larry Wickstrom at 614-265-6598 (). To order digital geophysical logs contact the Geologic Records Center at 614-265-6576.
 

The DGS has recently completed the initial phase of scanning all historic oil and gas well completion records in its files (in excess of 217,000 records) and entering the tabular data from the records into a relational database. The scanned images are now in a raw indexed format and the relational database records reside in a simple Microsoft Access database without a custom front-end to assist in data queries or use.
 
The DGS is now working with the Division of Mineral Resource Management (DMRM) and an industry focus group to assist us in establishing applications, image viewers, formats, update frequency and methods, etc. for final release of the data. This focus group will also assist the DGS in establishing a pricing schedule for this digital data, which may differ significantly from current pricing. We plan to have this process complete and all data released in final format by June 2006. We appreciate your patience during this transition of the data from paper to digital formats.

---

[ Back to previous page ]

---

Last update July 27, 2006
Division of Geological Survey   http://dnr/state.oh.us/geosurvey/