Expandable Tube-Suspended Recompletion Technology for Gas Injection Wells in Basement Reservoirs,Chad

The buried-hill basement reservoirs of oilfields in Chad demonstrate low pressure and low production of oil production wells.To improve the well production,gas injection is required to replenish the formation energy.However,the reservoirs are filled due to sand production in upper layers after the open-hole development wells are converted to gas injection wells.A lower completion string consisting of an expandable tube hanger and an open-hole packer was run in Well BX20 in buried-hill reservoir of Block B,Chad,for a pilot test of recompletion technology.The test results show that the designed recompletion string is set successfully in one trip,with the entire operation period of 10 d,which is 7 d less than the average operation period of traditional recompletion technology,corresponding to US$200 000 of workover costs or more saved.After the recompletion,the casing is effectively sealed and protected from damage caused by high-pressure gas injection,ensuring the wellbore integrity of the open-hole gas injection wells.The gas injection pressure reaches 20 MPa,and the daily gas injection rate reaches 2 000 m³/h.The proposed recompletion technology is proved suitable for gas injection wells in basement reservoirs in Chad,and has a demonstration effect on the development of similar oilfields.