4D seismic monitoring using horizontal wells – A synthetic case study from Troll

When producing from a thin oil layer with a gas-cap, gas is generally an unwanted component, because the reservoir looses pressure and its dynamic is changed. In this paper we validate by numerical simulations if permanent placing of the seismic tools in the horizontal production well would provide sufficient information about the gas-oil contact position. To our knowledge this type of seismic acquisition has not been done. Result for two out of six acquisition setups are presented: the best setup in terms of the gas-oil contact resolution and the most economical setup. An alternative way of data interpretation is utilized and the Troll field is used as the case example.