High water cut is a serious problem for mature oilfields in China. Water injection paths are intersected with each other, injectors and producers are distributed in a more and more complicated pattern, while low-productivity layers are more focused. Conventional zonal water injection technologies require repetitive operation with wirelines and cables, causing extensive tests and low efficiency. However, an intelligent zonal water injection string consisting of several preset cable packers, water injection pressure gauges, formation pressure gauges and downhole flow meters has simply optimized water injection parameters and efficiently developed all reservoirs in some China's mature oilfields.
Horizontal drilling and extended reach well drilling technologies are developing by high speed, we are faced by more critical borehole conditions, which has brought more challenges to water adsorption testing of horizontal intervals and deployment of zonal water injection instruments. Compared with vertical wells, the water adsorption test and string running are more challenging for horizontal wells, in which we are faced by many a problem during zonal water injection, such as competitive slack off and tight pull, excessive or inadequate water injection, complicated operation process, etc.
There are several common challenges arising from zonal water injection, such as tight pull, slack off and repetitive operation. A full set of wireless intelligent water injection string for horizontal wells has been proposed. Based on pressure pulse water distribution technique, the water injection string is eligible for multi-stage adjustment, so it is possible to finalize testing, adjusting, injection, measurement, downhole data collection as well as automatic error correction in one run during water injection. A dedicated trial shows that integration of remote wireless control and artificial automation may is applicable, as packers are set securely and released easily, in order to adjust opening of each water injection nozzle on the ground. Therefore, this completion and water zonal water injection string enables precise water injection by means of data remote control. The first trial was accomplished in Ghawar Oilfield, Saudi Arabia, showing acceptable results.
Integration of remote wireless control and artificial automation requires a wireless water injection string that combines testing, adjusting, injection, measuring and data collection in one trip, providing us with adequate downhole data. Thus, the complete water injection process for each zone is precisely monitored and controlled on the ground.