Publications

Monitoring of Gas-Oil Contact and Water-Oil Contact through time in Banyu Urip field has provided valuable surveillance data that has necessitated changes to simulation models and well operation strategy as well as reservoir management. The Banyu Urip hydrocarbon contacts were first logged in 2001. The original gas-oil contact (OGOC) was at approximately 4000ft TVDSS and the original oil-water contact (OOWC) at approximately 5000ft TVDSS, based on reservoir pressure analysis. In 2008/2009, when the five �early development� wells were drilled, formation pressures indicated very little to no movement of the hydrocarbon contacts across the field. In 2013/2014, during the initial part of the full-field development, formation pressure data indicated that the GOC had moved down significantly while there was no discernable movement in the OWC. This was different to what had been predicted in the simulation model where the OWC moved faster than GOC. In late 2014 / early 2015, baseline cased-hole Pulse Neutron Logs (PNL) were run. Both Sigma and Carbon/Oxygen data were acquired. These baseline logs were crucial to conducting time-lapse tracking of the hydrocarbon column. Since 2014, annual contact monitoring has been conducted. Specific criteria are set in order to select the best wells for the monitoring. These criteria include expected contact depth from simulation, reservoir quality, cement presence and completion hardware over the interval of interest. Additionally, the value of getting multiple contacts data in certain wells versus a spread of wells across the field is assessed. Interpretation of recent PNL data indicates that the GOC has moved down approximately 1.3 ft/MMBO and the OWC up approximately 0.5 ft/MMBO from the original contact depths. Simplistically, the data has shown that the gas has expanded faster than the water while there is less movement of the OWC. These learnings has been incorporated in both static and dynamic models and in field management strategy.