Abstract
Enhanced oil recovery has been gaining relevance over the years following success stories from already executed projects from various parts of the globe. The recoveries from such successful projects have tremendously increased the terminal life cycle recoveries from the subject reservoirs and subsequently the project Net Present Value and Value to Investment Ratio.
More than 90% of Field Development Plans in the Niger Delta have not considered Enhanced Recovery Mechanism as part of the field development options and as such Top Quartile Recovery Factors are never achieved.
In this study, the effectiveness of Enhanced Oil Recovery within the Niger-Delta reservoir sands via 3-Dimentional Dynamic Simulation, Economic models and Experimental investigations (temperature and pressure effects on polymer effectiveness) was done. The GN7000 reservoir was used as a case study for this work. This reservoir is the largest gas cap reservoir in the N-Onshore field within the Niger Delta area and it is at the mid-life stage.
This study tested the effectiveness of three Recovery mechanisms (Water Flood, Polymer Flood and Polymer Alternating Gas). Simulated and Experimental result suggests that Polymer flooding and Polymer Alternating Gas (PAG) yields greater Technical Ultimate Recovery, better economic indices but greater complexity in polymer selection due to inherent high reservoir temperature and low salinity that make the use of synthetic polymers inadequate. Experimental investigation showed that biopolymers are most suitable for this sand. The suitability of some biopolymers (Xanthan and copolymers containing high level of 2-acrylamido2-methyl propane sulfonate (AMPS) showed good results. Study results shows that with the deployment of biopolymers with high viscosifying power and high resistance to thermal degradation an incremental recovery of 8% from the natural flow could be achieved. Research findings indicate that biopolymers could yield good results for Niger Delta sands within the pressure and temperature ranges of 93°C and 290 Bar.