Performance analysis of horizontal wells for underground gas storage in depleted gas fields

Underground gas storage is a common activitity in countries with major transport and distribution gas pipeline infrastructures, which allows to efficiently resolving demand seasonality problems. The first ever underground gas storage project in Turkey is being carried out in the KM field with injection and withdrawal operations. Optimization of gas storage field was enabled by an improved reservoir and geologic description, including the evaluation of deliverability and storage capacity in the reservoir. Based on available information and those generated by simulation model, KM field is the best candidate for underground gas storage. The KM offshore natural gas field was discovere in 1988 located about 3 km off the shore of Silivri in the Marmara sea. The field was initially planned to be developed with 3 wells, but recently 2 additional wells were added during the development of the field hence increasing the depletion rate. In this study, after gathering necessary reservoir, fluid, production and pressure data, IMEX (CMG) simulation program was used for history matching of depletion of the field. Reservoir performance after history matching using depletion scenario was predicted and depletion last for 4 years. In 2005, 5 ERD wells were drilled in KM field from onshore drilling site location for gas storage application. Five scenarios were developed for forecasting of injection and withdrawal performance of the reservoir. These scenarios were used 5 newly drilled horizontal wells with combination of existing vertical wells. With a predetermined injection rate of 65 MMscf/day was set for all the wells and among all scenarios, 5 horizontal - 5 vertical injectors and producers was the most successful in hamdling the gas inventory and he injection period was 5 months and production period was 7 months, respectively. After the determination of the well configuration, the optimum injection rate for the entire field was obtained as 65 MMscf/day by using horizontal gas injection wells. The total produced gas volume until 2012 was estimated as 394 Bscf with this optimum gas injection where the maximum average reservoir pressure was 1901 psi and cushion gas pressure was 1270 psi by withdrawal. Copyright 2007, Society of Petroleum Engineers.