Surveillance of the waterflood through carbon/oxygen logging, of the formation through compaction logging, and of the individual reservoir layers through multi-rate production logging is critical to the success of the Mars field. The program has consisted of obtaining time-lapse logging and reservoir pressures combined with reservoir modeling. Data has been obtained in the injection, producing, and monitor intervals of several Mars wells and proven to be vital to the evaluation of waterflood efficiency and the prediction of the waterflood front.

 A monitoring logging program has been conducted in the Mars area since 1996, with initial baseline surveys, to the present day monitoring surveillance program. The logging program has had two purposes. The primary purpose of the program has been to monitor the “sea water” waterflood saturation fronts with carbon/oxygen logging and integrate this data into the reservoir models. A second purpose has been to monitor strain as a result of reservoir compaction and to monitor the effects of the waterflood on the rate of strain. This data is used to help determine wellbore integrity and ultimately to predict wellbore failure. It also provides calibration data for the compaction model used in reservoir simulation.

Selected Mars well examples are described in detail to highlight the results of time-lapse monitoring of the waterflooded reservoirs. A comparison of log data with simulation modeling predictions demonstrates the benefit of the data acquisition and evaluation methods. Discussion is focused on best practices learned during the 12 year program, how log responses have he