Tracking interwell water saturation in pattern flood pilots in a giant gulf oil field

Peripheral water flooding has been the preferred pressure maintenance tool for many gulf carbonate reservoirs over the past 30 years. Due to uneven sweep and pressure distribution, this technique has given way to pattern floods in several gulf fields. As these new floods are established, it is important to understand the water saturation between wells to properly manage the sweep and recovery. In 2007, ADCO initiated water injection (WI) and WAG pilots to test the recovery strategy. The pilot employs advanced geophysical and modeling tools to measure formation properties at the wells and between wells; this paper discusses the WI pilot. Among the novel techniques applied is the crosswell electromagnetic method, which measures the interwell resistivity distribution between observation wells at the pilots. Interwell resistivity data can be used to infer the water saturation distribution because of the sharply different electrical resistivity between injected water and oil bearing reservoir rock. By allowing an evaluation of the water distribution long before the injected fronts reach producers or observers, a better and more rapid understanding of the pilot arises from the crosswell electromagnetic technique. In this paper, we briefly describe the pilot design, describe the detailed geological model and show results from the initial set of baseline and time lapse EM data sets from the water injection pilot. The images highlight the influence of background geological constraints on the flow.