The use of web services as a means of accessing thematic geodata can enable improving the support of increasing cameral exploration works related to clarification of poorly explored areas’ geological structure, old oil and gas provinces and complexes with hard-to-extract and unconventional hydrocarbons. The author considers the methodological foundations for preparing web services` graphical user interface. The graph for defining the functional purpose of geodata and its processing method at creating the content is proposed. Guidelines are given to choose the scale level, base and dynamic layers content for the primary web-mapping image depending on the exploration stage and area of interest location. Examples of possible web-service interface structures illustrating the character of web-pages interaction inside a web-service are considered. To formalize the choice of the structure the decision graph was developed depending on the number of survey sites, requirements for publishing thematic geodata on one or more web pages, as well as the need for an initial one as a common window of access to information for individual working groups of specialists. Approbation of web-services, developed on the considered methodological principles, was carried out in the production process of the industrial branch arrangement. The results allowed supplementing the capabilities of specialized software system, reducing the time spent by specialists on comparing different sources of data in a single geo-information space. The proposed solutions can be used at making web-services for other topics