One of the major problems of development of fields with gas caps and oil rims is breakthrough of the gas to the bottom holes of producing wells. This problem becomes bigger if the gas is re-injected into the gas cap in order to maintain the reservoir pressure. Because of the big difference in mobility ratio, the gas "plugs" the oil in the reservoir and in the well bore and that materially reduces the oil production rates. Considering gas processing facilities limitation, the gas production growth the load increases and restricts the total volume of associated gas production at the field. This results in production cuts or shut-ins of the wells with high gas-to-oil ratio (GOR) and oil production losses. The gas processing infrastructure expansion option is not economical and it requires long time for design and construction. Another approach to solve above mentioned problem is to run well work activities for shutting off gas break-through intervals in the producer wells for GOR reduction. This article reveals unique experience of Rosneft Oil Company shutting off gas break-through intervals at the Northern edge of Chaivo oil-gas-condensate field on Sakhalin Island offshore. Rosneft has identified and shouted off gas break-through intervals in the extended reach horizontal well at 9800 m MD. The article reviews the equipment and the technology that used for production logging tests (PLT), the approach to candidate wells selection based on PLT, the equipment and activities for gas shutoff; also, oil production results after gas shutoff are provided.
References
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