From Data Acquisition to Simulator: Fracture Modeling in a Carbonate Heavy Oil Reservoir (Lower Shu’aiba, Northern Oman)

Georg Warrlich*, Richard Pascal, Tim Johnson, Bart Wassing, James Gittins, Ali Lamki, Murshid Riyami, and John Van Wunnik
PDO
*[email protected]

A dedicated appraisal campaign and modeling study was carried on an heavy oil, fractured Shu’aiba field in northern Oman to assess the feasibility of steam-assisted GOGD EOR. In this field, key to a successful SAGOGD is a well-connected fracture network, which was investigated by drilling three horizontal wells. Borehole image, sonic and resistivity logs were run in the wells to understand static fracture characteristics; dynamic behavior was assessed with drill stem tests and PLTs. The fracture models were built with forward modeling algorithms using Shell’s SVS fracture modeling software. They are based on fracture characterization that integrates the well data with 3-D seismic, the field kinematic structural evolution and the regional understanding established by PDO’s long-term activities in the area and analogue sandbox models. This integration renders the fracture models more realistic than purely stochastic fracture models that only honor the field data. Interdisciplinary collaboration during data acquisition and all stages of the modeling assured that only the features relevant to the dynamic behavior of the reservoir were modeled while at the same time the geological details of matrix and fracture models were captured sufficiently in the simulator. Simulations were run in dual-porosity dual-permeability thermal mode in Shell’s dynamic simulator. Three loops of full static-dynamic modeling were completed which streamlined and focused the model building without compromising the details. The results are fully integrated model scenarios that are directly and quantitatively comparable to the PDO fractured Shu’aiba fields facilitating management’s technical decision-making on the EOR strategies for the fields.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain