Polymer Flooding in a Large Field in South Oman - Initial Results and Future Plans

Abstract

In heavy oil reservoirs, water flooding leaves behind unswept hydrocarbon volumes due to unfavourable mobility ratios resulting in low ultimate recoveries. Increasing the viscosity of the injected water using polymer improves the water-oil mobility ratio resulting in improved recovery factors. This paper discusses for a large field in South Oman the successful implementation of a polymer flood project, the early results of Phase I and the planned expansions to Phase II and Phase III. Following a number of field trials and a series of laboratory studies, a full-field polymer project was implemented in the field in 2010. One of the key risks identified prior to starting the project was poor polymer injectivity. However, initial field results showed better injectivity than expected. Surveillance efforts are in progress to understand the better injectivity. The data analysis so far indicate that wellbore clean up due to polymer injection, improved as a result of improved mobility ratio and small scale induced fractures in some injectors are contributing to the improved injectivity. These factors enabled injection of more volumes of polymer than planned resulting in improved volumetric sweep efficiency and producer response. Results to date are encouraging, as after over a year of polymer injection, the oil gain due to the polymer flood is higher than expectation. Based on the initial results of Phase I, expansion phases II and III are being planned. Phase II is based on utilizing the available ullage in the system to accelerate the oil gain from polymer; it requires a relatively small upgrade of the existing infrastructure and surface facilities. Phase III is a full-field polymer flooding expansion combined with an intense infill drilling. Currently, a study is in progress to optimize the development concept for the infill wells and polymer flooding of Phase III.

Effect of Dissolved Iron and Oxygen on Stability of Hydrolyzed Polyacrylamide Polymers

“…First, for many of the largest polymer floods (e.g., Daqing, Shengli, Pelican Lake), no effort was made to eliminate dissolved oxygen or control oxidation in the injected polymer solutions. Because these low-temperature polymer floods were quite successful in recovering oil (Wang et al 2008(Wang et al , 2011Zhu et al 2013;Delamaide et al 2014), it seems likely the HPAM polymers did not suffer severe degradation. Manichand et al (2013) demonstrated that HPAM solutions propagated more than 300 ft through a reservoir (at 38 C) with no significant degradation even though the injected solutions were saturated with dissolved oxygen.…”

“…This approach was applied in some field applications. In particular, the polymer flood at Marmul uses a free-radical scavenger formulation (Koning et al 1988;Al-Saadi et al 2012).…”

Recovery rates, enhanced oil recovery and technological limits

“…The recent rise in oil price has initiated a renaissance of the technique among the international oil companies with applications underway in Angola [65] and Oman [66] as well as many being planned for other regions including the UK North Sea [67]. …”

Optimization of a Large Polymer Flood With Full-Field Streamline Simulation

“…The polymer-flood project is implemented in phases. Phase 1 of the project, that is currently in operation, is targeting areas in which reservoir characteristics are similar to those in the initial polymer pilot (Teeuw et al 1983;Koning and Menzter 1988). Polymer injection takes place through 20 inverted nine-spot patterns, four inverted five-spot patterns all with vertical injectors, and three additional patterns with horizontal injectors.…”