Canadian Petroleum Ltd. and partners in the Yemen Masila Block have successfully used detailed three-dimensional reservoir modeling and reservoir simulation to optimize the development of the larger oilfields in the Masila area. The models were used to predict reservoir performance and plan additional development drilling which subsequently demonstrated that the models accurately predicted drilling results. The main producing horizon in the Masila area is the Cretaceous Upper Qishn formation, a clastic-dominated transgressive depositional sequence with fluvial sediments at the base, tidal dominated estuarine sediments in the middle, and marine shoals at the top. This variable array of facies presents modeling challenges but the resulting heterogeneous models provide a realistic representation of actual reservoir characteristics. This paper describes the approach used to stochastically distribute both facies bodies and petrophysical parameters, and to upscale the model for reservoir simulation, while preserving the complex reservoir description. The Tawila field was the first Masila field to have wells drilled on the basis of the modeling effort, with very encouraging results. For these new well locations, the model successfully predicted both reservoir development and oil- water contact movements resulting from production from existing wells. This paper presents key conclusions and predictions from the modeling and reservoir simulation, and compares them to the results from subsequent drilling. As a result of the successful development drilling, these models are now an integral part of reservoir management and development planning for all Masila fields. P. 715

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractCanadian Petroleum Ltd. and partners in the Yemen Masila Block have successfully used detailed three-dimensional reservoir modeling and reservoir simulation to optimize the development of the larger oilfields in the Masila area. The models were used to predict reservoir performance and plan additional development drilling which subsequently demonstrated that the models accurately predicted drilling results.The main producing horizon in the Masila area is the Cretaceous Upper Qishn formation, a clastic-dominated transgressive depositional sequence with fluvial sediments at the base, tidal dominated estuarine sediments in the middle, and marine shoals at the top. This variable array of facies presents modeling challenges but the resulting heterogeneous models provide a realistic representation of actual reservoir characteristics. This paper describes the approach used to stochastically distribute both facies bodies and petrophysical parameters, and to upscale the model for reservoir simulation, while preserving the complex reservoir description.The Tawila field was the first Masila field to have wells drilled on the basis of the modeling effort, with very encouraging results. For these new well locations, the model successfully predicted both reservoir development and oilwater contact movements resulting from production from existing wells. This paper presents key conclusions and predictions from the modeling and reservoir simulation, and compares them to the results from subsequent drilling. As a result of the successful development drilling, these models are now an integral part of reservoir management and development planning for all Masila fields.