The Water Alternating Gas (WAG) process is a cyclic process of injecting alternating water followed by gas. The main purpose of WAG injection is to improve both macroscopic and microscopic sweep efficiency, maintaining nearly initial high pressure, slow down the gas breakthrough and reduced oil viscosity. WAG injection also decreases the residual oil saturation resulted from the flow of three phases and effects associated with relative permeability hysteresis. The study area is in the Cornea Field located in Browse Basin, Western Australia. This study is conducted because there is no investigation on WAG injection feasibility in this field. In this study, two-phase bounding imbibition and drainage relative permeability model (Stone 1 and Stone 2) along with two-phase hysteresis model (Land, Carlson or Killough) were used. From the result, Carlson two-phase hysteresis model with Stone 1 correlation shows more oil was recovered. Therefore, it is a feasible model to be used compared with other models. From sensitivity analysis, it shows that highest oil was recovered at WAG ratio 1:1. Since it is a miscible reservoir, 1:1 ratio is more efficient and it is insensitive to trapping. Also, oil production increased with the shortest WAG cycle time at 180 days due to minimum miscibility pressure reached. In addition, it is best to inject water as the first phase to be injected into the reservoir compared to CO$$_{2}$$ 2 because water has high mobility ratio while CO$$_{2}$$ 2 can result in early breakthrough in the reservoir.

Carbon dioxide (CO2) injection is implemented into the reservoir to further improve the oil production efficiency, by mixing with oil at reservoir condition, and becomes miscible. The miscibility affects the oil to become swelled and less viscous and thus easily flow through the reservoir. Most of the (CO2) EOR projects has higher recovery factor in miscible condition. Therefore, this article aims to determine the effects of the miscible (CO2) injection on production recovery in the Cornea Field. The Cornea Field is located in Browse Basin, Western Australia. It is a simple trap structure which is elongated and formed by unfaulted drape anticline over an eroded high basement. The importance of this research is that (CO2) injection has not been implemented in the Cornea Field since it is a complex reservoir. However, research showed that there was a high potential production recovery in this field. Therefore, research needs to be conducted to determine the effectiveness of the (CO2) injection on production recovery in this field. The model was validated, by comparing MMP obtained from the simulation model and correlation methods. The MMP of this reservoir is above 38 Bar. Sensitivity analysis on reservoir pressure, reservoir temperature and (CO2) injection rate was investigated. Oil production increases with the increase in reservoir pressure and reservoir temperature. As the (CO2) injection rate increases, oil production also increased. From the result, hence, this study should contribute to the knowledge gap in Cornea Field.

The research of the current study is primarily focused on evaluating the reservoir performance by utilizing waterflood technique, based on a case study at Lanea oil field located in Chad; various mechanisms along with approaches were used in considering the best suitable pattern for waterflooding. All the simulation work was compared against a base case, where there was no involvement of water injection. Moreover, for the base case, a significant amount of oil left behind and cannot be swept, because of lower reservoir pressure at the downhill. The recovery factor obtained was in the range of 14.5–15% since 2010, and in order to enhance the oil production, an injection well was applied to boost the reservoir pressure; oil recovery is improved. In addition, sensitivity analysis study was performed to reach the optimum production behavior achieved by possible EOR method. Parameters, such as grid test, injection position, proper selection production location, permeability, and voidage substitution, were defined in the simulation study.

The focused area in this study is in the Cornea Field located in the Yampi Shelf, north-eastern Browse Basin, Australia. The field was stated to be an elongated unfaulted drape anticline over highly eroded basement. From the literature and seismic data, faults die at the basement in the Cornea Field. Therefore, no faults were considered previously. The tectonic activity was not apparent in the area with only deformation by gravitational movements and compaction in the basement zone. However, fault might present in the reservoir and seal depth as time passed. Therefore, the aim of this study is to simulate the Cornea field with faults, to determine the effect of fault transmissibility on oil production. The study shows that the fault permeability and fault displacement thickness ratio have a close relationship with fault transmissibility. The fault transmissibility increases when fault permeability and fault displacement thickness ratio increase. Transmissibility multiplier was also considered in this study. The fault transmissibility increases with the increase in transmissibility multiplier, thus the oil production. This study contributes to the gap present in the research of the Cornea Field with fault structure, where it is important to consider fault existence during exploration and production.