Investigation of Effects of Well Configurations on Reservoir Recovery Efficiency Based on Coupled Geomechanical Models

Xing Zhang¹*, Nick Koutsabeloulis¹, and Kes Heffer^2
1Schlumberger, UK
²Reservoir Dynamic Ltd., UK
*[email protected]

The impact of well configurations on reservoir recovery is investigated based on a coupled geomechanical model. This areal model simulated 36 months of production and injection in 49 wells in a stressed and fractured-faulted reservoir, which is geologically similar to the Gullfaks reservoir in the North Sea. The coupled model is capable of simulating the interaction between reservoir rock deformation and permeability changes, both in intact rock and in fractured-faulted rock. The intact rock was simulated as an elastoplastic material, and the faulted-fractured rock as a Mohr-Coulomb material. Three scenarios of well configurations were investigated. The same sequence of random, uncorrelated pressure changes at wells was input in each case, and the consequent production and injection rates at wells were output for analysis. In Case 1, there were 25 producers and 24 injectors, in which each producer was surrounded by 4 injectors. In Cases 2 and 3, there were 28 producers and 21 injectors with 4 rows of producers and 3 rows of injectors, but the direction of rows was different in relation to the regional horizontal stress direction and the major faults. Due to the difference in well configurations, significant fracture-related permeability enhancement occurred in Cases 1 and 3, which resulted in significant difference in total production rates and injection efficiency. The total production rate was about 75% higher in Case 1 than in Case 2, and the injection efficiency was about 20% higher in Case 1 than in Case 2. In addition, Spearman rate correlation coefficients were used to identify the most efficient production-injection wells. The study revealed a very strong influence of geomechanics on the reservoir performance.

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