METHOD OF ESTABLISHMENT OF SEARCH AND PROSPECTING HOLES Russian patent published in 2002 - IPC

FIELD: oil and gas industry. SUBSTANCE: method is used to determine points of breaking ground for search and prospecting holes across fields containing traps of structural type. Three search holes are drilled in anticline, periclinal and limb parts of fold in accordance with present structural plane of examined area. Logging examinations are carried out in holes. Reference horizons confined to lithologicstratigraphic boundaries are isolated in sections of holes on basis of analysis of logging diagrams. Horizons promising inflow of hydrocarbon fluid are tested. Then paleomarks of promising horizon for moment of agglomeration of exposed reference horizons in geological time interval in search holes drilled in antiline, periclinal and limb parts of fold are determined. Later differences of paleomarks of promising horizon for moment of agglomeration of exposed reference horizons in geological time interval between search hole drilled in anticline part and search holes drilled in limb and periclinal parts of fold are found. Intervals corresponding to last phase of most intensive growth of fold are isolated in sections of holes. Values of potencies of these intervals in each search hole are found and these values are marked on existing structural plan of examined area. Tendency of change of these potencies is determined on existing structural plan and next search and prospecting holes are drilled in zones of minimal values of these potencies. If exposed potency in next search and prospecting holes corresponding to last phase of intensive growth of fold is not less than potency in search holes drilled in structure outside outline of field then drilling is stopped without trying until promising horizon is revealed. EFFECT: reduced number of non-productive search and prospecting holes in process of search and prospecting for oil and gas occurrences with intricate geological structure with minimal body of starting information under conditions of lack of correspondence in structural plans. 2 dwg, 1 tbl