Optimal Development of a Virgin Heavy Oil Reservoir with Multiple Zones, Fluid Contacts and Structural Uncertainties in the Niger Delta

Abstract Traditionally, the development of heavy oil reservoirs is not attractive to marginal field operators, due to challenges such as low Expected Ultimate Recovery, complex well trajectory, early water breakthrough and high operational cost. However, there has been a recent shift from the old ideology of "abandon" to "development", owing to improved technology and depletion of conventional oil resources. This paper is focused on a virgin reservoir B within the Niger Delta that has good reservoir properties, multiple fluid contacts observed from logs and supported by RFT. The reservoir fluid viscosity is 12cp with an initial solution gas of 32 scf/stb. Two different seismic vintages resulted in two slightly different structural relief. The old seismic vintage shows the structural relief increasing towards the Northeast but in the newly interpreted seismic vintage, the structural high increases towards the Northwest. Simulating these two static model realizations would result in different production profiles. An integrated approach utilizing static and dynamic modeling processes was adopted to evaluate the development of reservoir B. Various well trajectory types were considered during reservoir simulation and well planning. A relatively poor performance was observed from the vertical well path due to rapid water breakthrough. The deviated well path indicated a better performance than the vertical. However, the horizontal well path was finally selected as the most optimal to drain the reservoir due to delayed water breakthrough time compared to the vertical and deviated wells. Sequel to the horizontal well selection, the two structural models from different seismic vintages required the optimization of the horizontal well path whose major constraint was the fixed surface location, and this led to the selection of Well path 3 with recovery of 0.97MMstb. In conclusion, heavy oil field development requires detailed integration of subsurface data to help maximize opportunity.