Water Injection Fall-Off Tests in Deepwater Reservoir: What Do We Actually See Into Formation?

Water injection is an important recovery method in<br>deepwater reservoirs. A certain water injection volume is<br>required to maintain target oil production. A short<br>injection / fall-off test is therefore often conducted to<br>evaluate well injectivity performance prior to oil<br>production. Following that, permanent downhole gauges<br>are set to monitor full field development scale. Pressure<br>transient data from the permanent gauges are then also<br>analyzed as long-term injection and fall-off tests.<br>Reservoir parameters, such as permeability and skin<br>factors can be obtained from these short- and long-term<br>tests. However, several questions must be asked about the<br>interpretations, such as 1) What do we actually see into<br>formation, i.e. injected water or reservoir oil? 2) Do the<br>permeability and skin values change with time? 3) How<br>can we capture and understand reservoir changes versus<br>time?