ABSTRACT

The Ohio Division of Geological Survey, along with the Ohio Division of Oil and Gas, are transferring oil and gas well spot maps to digital map files. Currently, oil and gas wells are spotted by hand onto County Engineer/County Auditor tax maps. Transferring the well spot maps from a paper to a digital realm will result in a more accurate, easily readable, applicable product. The ability for the public to access the new digital well spot maps will result in broader, more innovative usage of the oil and gas well information.

The building of the digital oil and gas well spot maps is a multi-stage process. The digital base maps used in this project are assembled from the U.S. Geological Survey Digital Line Graph (DLG) files of the 7.5 minute topographic maps of Ohio where possible. These maps are exact reproductions of the U.S. Geological Survey 7.5 minute topographic maps and are currently being created as part of a cooperative project between the U.S. Geological Survey and the state of Ohio. All the Ohio DLG topographic map files will be finished and available by the end of 1997. For those areas currently not covered by the DLG files, the political boundaries and the section lines are accurately digitized from the U.S. Geological Survey 7.5 minute topographic maps. The DLG quadrangle map files are then compiled into county map files. Once compiled, the irregular, original land subdivisions are digitized into the county base map files. The state of Ohio has twelve major schemes for land subdivision. Only in northwestern Ohio does the land subdivision correspond to the Public Land Surveying System (PLSS). The irregular lots, tracts, allotments, and subdivisions are digitized from the well spot maps and all attempts are made to exactly reproduce the irregular subdivisions.

The original mylar township-well-spot maps, along with the new digital county base maps, are sent to the contractor to digitize the well locations and enter the data elements surrounding each well. The contractor for this project is Ohio Penal Industries, under the project management of Lockwood, Jones, and Beals, Inc. For this project, the contractor has built a customized data entry and digitizing system, which includes special options for reproducing the well symbols and creating a database containing the well location and up to seven other attributes per well. The data attributes captured as part of this project include the permit number, the lease number, the initial production of gas and oil, type of well permit, and up to two producing horizons. Upon receipt of the well spot maps and digital base maps, the contractor separates the county base map file into its component townships. The contractor then rectifies the original mylar township-well-spot maps to the new digital base map. The setup of the township well spot map to its corresponding digital base map is required to have a misclosure of no more than 50 feet. If the misclosure is larger than 50 feet, then digitizer setups will occur on progressively smaller areas until the misclosure is acceptable. After the well spots are digitized, they undergo quality control checks by both the contractor and the Ohio Department of Natural Resources. The digital files are checked to ensure that all oil and gas wells were digitized, locations are correct, well attributes have been correctly entered, and that the maps are cartographically readable. Once the visual quality control has been completed, a computer database file is generated, consisting of the coordinates of the well and the attributes surrounding the well. The database is also put through quality control checks to test for any major mistakes.

There are many results that will come from this project. We will be moving away from mylar and paper well spot maps. One major advantage of the new digital well spot maps is that they will not decompose over time as do the paper maps. The mylar township well spot maps suffer from readability problems. As wells are spotted on the mylar maps, original information is being erased due to cartographic readability issues. This information is lost forever. Using sophisticated visualization and plotting techniques, information can be faded and screened to enhance readability and avoid the loss of ancillary information. The new base maps are far more accurate than the County Engineer/County Auditor tax maps that are currently being used as base maps. The U.S. Geological Survey 7.5 minute topographic maps were created using aerial orthophotography and field surveying. The U.S. Geological Survey map makers used the surveyed distances from the original plats of the 1790's and early 1800's to find the section and township corners in the field. The location of these section and township corners were then transferred to the topographic maps, giving us great confidence that the section lines are accurately represented in both the 7.5 minute topographic maps and their digital representations, the DLG files. These new digital well spot maps are the beginnings of an integrated geographic information system for the Division of Geological Survey and the Division of Oil and Gas. The graphics that symbolize the well locations are attached to an initial database that will grow over time as data is added from the Division of Geological Survey well cards and records from the Division of Oil and Gas. The digital data will enable the rapid update of the well spot maps and enable the public to perform more complex analyses. The planned project completion date is January 1997.