Since the development of computer-processable well-data files began in 1961, more than 600,000 wells have been included in systems covering most of the United States and Canada. These systems contain information on ownership, location, well classification and status, drilling and completion activities, tests, depths to formation tops, core descriptions, shows, and other data. Data are obtained from the most reliable and complete source for each area and are upgraded by computer editing and the feedback of missing data and corrections from file users.

Well-data files are used at various stages of the exploration process for basin evaluation, for selection of prospective stratigraphic intervals and areas for further study delineating prospects for acreage acquisition or drilling, and for building peripheral files containing proprietary, technical, and economic data. A study of the Muddy Sandstone in the Powder River basin illustrates an exploration application of computer processing a large well-data file. Prior to the discovery of Bell Creek, data from the file revealed areas in Wyoming and southeasternmost Montana with abundant hydrocarbon shows in the Muddy Sandstone. North and South Dakota and the rest of Montana had no oil shows in the Muddy Sandstone. In the area of abundant shows geologic maps based on formation tops obtained from the file indicated trends on which subsequent drilling has discovered more than 525 million bbl of reserves. Two types of depositional areas favorable for hydrocarbon occurrence were indicated. One was related to deposition around a pre-Muddy positive feature defined by Skull Creek structure and isopach residual maps of the Muddy Sandstone. The other was a channel system defined on an isopach residual map. Approximately 750 wells have been drilled in the "no show" area without discovering commercial oil.

At the time of discovery of Recluse and Bell Creek, information was available within the Rocky Mountain Well History Control System to suggest areas favorable for similar types of production from the Muddy. With addition of new well control and proprietary information, the well-data file can aid in the planning of development drilling, analysis of completion practices, and reservoir evaluation. Large well-data files and proper application of the computer to these data will become increasingly important in the discovery of oil and gas during the 70's.

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