Michael, Q. Ye¹, Denise, N. Pfeffer¹, John, J. Spokes², Kelly Scarborough³, Michael, E. Strickler³

(1) Upstream Technology, Texaco, Houston, TX
(2) Commercialization and Development, Texaco, Houston, TX
(3) Commercialization and Development, Texaco, Bellaire, TX

ABSTRACT: Depositional System and Flow-Units-Based Earth Modeling of Deepwater Turbidite Prospects

Great progress has been made in recent years in reservoir modeling. Sophisticated software with versatile functionality has been developed. Well log data, inverted seismic data, and impedance volumes from high-resolution stochastic inversion are gradually integrated into earth-model building. Due to the limited resolution of seismic data, however, meter-scale reservoir heterogeneity is not yet incorporated into the model. In our research, we developed a methodology to integrate depositional facies and lithofacies (flow unit) into the model building to improve the representation of fine-scale reservoir heterogeneity. Studies show that different lithofacies, such as massive, parallel-stratified, and ripple-cross-bedded sand beds in deepwater turbidite deposits have very different reservoir properties, thus, forming different flow-units. These lithofacies are coded into the model to represent the realistic reservoir heterogeneity.

Lithofacies distributions are controlled by depositional facies. By understanding regional depositional system, a depositional facies model can be estimated. This estimation can be guided in areas by high-quality seismic data. A grid of pseudo-well logs composed of lithofacies is then generated to construct the model.

We have applied this method in different depositional settings such as channel-levee systems and fan lobes, with very exciting results. Since this approach requires much more geological inputs and is depositional model driven, a reservoir model can be built in areas with very poor seismic data, such as sub-salt prospects. It also allows us to build a reservoir model early in the exploration stage (pre-drill) as well as in the commercialization stage, thus facilitating asset transition, knowledge transfer, and reducing cycle time.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado