METHOD OF EXPLORING OIL-GAS DEPOSITS Russian patent published in 2001 - IPC

FIELD: drilling of directional wells for exploration of oil and gas deposits. SUBSTANCE: method includes drilling of parent horizontal wellbore, core sampling, drilling of upward and downward branches which are drilled with determination of formation roof and foot. Then subjected to exploration from bottom-hole of parent horizontal wellbore are upward and downward branches down to crossing of roof and foot of formation. Upward branches are drilled orientless by downhole drill string assembly with positive deviation force on bit, and downward branches are drilled by downhole drill string assembly with negative deviation force. Downward branches after testing and research without tapping of bottom water are subjected to short-term preservation, and in case of tapping of bottom water, they are subjected to long-term preservation. Deepening of parent horizontal wellbore is carried out by downhole drill string assembly with bit zero deviation force to boundary of producing formation wedging-out. Upon completion of well research, geological section of producing formation in plane of horizontal wellbore and its branches is constructed. Claimed method of exploration provides for more detailed information pool structure and reservoir properties of formation in vertical plane along horizontal wellbore. Drilling of several clusters of horizontally branched wells gives three-dimensional structure of pool with high efficiency of subsequent pool development. EFFECT: higher efficiency of search, exploration and subsequent development of hard-to-reach oil and gas deposits. 2 dwg