Borehole Database
The borehole database was brought into being in the frame of the co-operation project between MÁFI and MOL Rt. (Hungarian Oil and Gas Company) between 1998 and 2002 aimed at the generation of a GIS-based geoscientific database. The reinterpretation of borehole logs was executed upon the uniform litho-stratigraphy-based legend system. Harmonisation and modernisation of the database took place in 2003.
During the work some 41 890 borehole logs were reinterpreted according to harmonised formation-based geological units considering modification proposals made at both the mapping and borehole reinterpretation phases of the project
Overview map of deep boreholes of Hungary
As a result of the project the harmonised borehole and map database has been established for the most part of Hungarys hilly areas (except for Budapest and the western boundary) as well as for some lowland regions. New litho-stratigraphic units had to be introduced in different parts of the country, some others were modified. In this process we attempted to reach wide ranging professional consensus. New proposals were submitted to the subcommittees of the Hungarian Stratigraphic Committee for revision.
The structure of the borehole database (according to the PhD dissertation of L. Gyalog)
Physically, the borehole database is made up of several individual tables including data of boreholes, borehole sequences, counties, settlements and the names of interpreting professionals. They can be merged into one table with optional fields and queries tailored to the user needs. Naturally, if required the whole database can be merged in one table.
Physically, the database is stored in SQL Server and it is available for the users through a web-based application accessible in the Institutes Intranet. Applying menu-driven queries the users can create Excel-format outputs. The following description presents the structure of this output as converted to Excel format. Naturally the tables of the SQL Server database constitute a relational database with master- and code tables linked through unique identifiers eliminating redundancy.
In the user-friendly Excel-format output single units of the geological sequence occur as separate rows under each other with master data repeated in each row. Optionally it is possible to display several interpreted versions of the borehole profile if available. In the complete sequence the archive sequence appears first (code number 0) followed by the first version of reinterpretation (code number 1) and occasionally a second one can also be available (code number 2). The currently up-to-date sequence of the borehole is the one featuring the highest code number. The table that can be accessed below shows this example featuring the sequence of boreholes Bsz-52 and Bsz-55.
Borehole sequences on the example of boreholes Bsz-52 and Bsz-55 (the main items of the database)
The main fields of the database can be described as follows: FRS_ID (borehole identifier) is a code number unique for a given borehole. The units of the geological sequence as well as settlement and county names and the name of interpreting geologist are also identified by similar code numbers that were omitted in the table due to lack of place. Three settlement names are registered (TELEPULES is featured in the table). The first one is the original recorded in the archive documentation. The second one corresponds to the actual settlement boundaries distinct of the archive as a result of integration, splitting or some area transfer. The third one was given by us. Beside the settlement name it was attempted to specify the name of the site that gave the sign of the borehole, if necessary (e. g. for the boreholes signed Tü- with settlement name Csabdi: Csabdi, Tükrösmajor). The database includes also the abbreviation of county name.
Boreholes are georeferenced by their EOV (Uniform National Projection) X and Y coordinates as well as their altitude above Baltic See level (mBf, Z). If coordinates in the archive were available in earlier used, mostly stereographic or cylindrical projections (HKR, HDR, etc.) they were immediately converted in EOV. If the X, Y coordinates were missing or false it was attempted to find them in the original documentation or other literature. If the Z coordinate was absent it was specified in 1:10 000 (Stereographic or EOTR) topographic maps with a precision of 1-2 m.
Apart from other master data (e. g. BEF year of completion, JEL_SZAM sign and number of the borehole) the work was focused on the reinterpretation of the geological sequence. The field FS shows the version of reinterpretation. The actual definition of the given geological unit is provided in the field GEO_NDX (geological index) corresponding to the unfolded index in the GEO_NDX field of the uniform legend (see in chapters 8.1 and 7.1.2.8). As specified above for Quaternary deposits it is a genetics-based index with lithological data added (e. g. eQp3l loess). For pre-Quaternary assemblages described in detail the formation-based symbol is generally complemented by the index of lower ranked units (member, bed, volcanic facies), and /or some lithological signs (e. g. s_sE2, where the sign _ separates the upper-left and lower-left indexes.
The top and bottom of the layers as well as their serial number pertain also to basic information. Though not present in the displayed table the name of reinterpreting specialist and the year of reinterpretation are also specified for each layer.
