EOR Opportunities on the Gyda Field, a WAG Injection Simulation Study

Abstract

Gyda is a mature oil field located in the North Sea. Gyda is experiencing challenges with declining oil production and increasing water-cut. A study of the EOR potential on the Gyda field is performed.

A review of conventional EOR methods is performed. Based Gyda EOR requirements, a WAG injection simulation study is performed to evaluate the increased oil recovery potential from WAG injection. The simulation study is performed on Eclipse 300 Compositional Reservoir simulator.

A black oil dynamic reservoir model is received for this thesis and the conversion from black oil to compositional modeling is described.

Hysteresis effects on the relative permeability of gas during WAG injection are evaluated. Killough s, Carlson s and WAG hysteresis option in Eclipse are evaluated. Stone s first and Stone s second method for defining three-phase relative permeability curves are compared to each other.

Stone s first method is chosen to create the three-phase relative permeability curves, and Carlson s method is chosen to capture the hysteresis effects on the relative permeability of gas during WAG injection.

WAG cycles sensitivities are run. Simulations show that WAG cycle periods of six months are beneficial when there is a substantial distance between injector and producer. Shorter WAG cycles are beneficial when producer and injector are closer and have good communication. WAG cycle lengths are not critical for the ultimate oil recovery.

WAG injection on Gyda with dry injection gas can increase the recovery by 1.4% by 2021. Including gas relative permeability hysteresis gives more optimistic prediction for WAG injection studies.