Performance Review of Polymer Flooding in a Major Brown Oil Field of Sultanate of Oman

Abstract

The first field scale Polymer flood project in the Middle East region is being implemented in an oil field of Sultanate of Oman from early 2010. The oil field discussed here containing viscous oil (90 cp) was discovered in 1956 and is located in eastern part of South Oman Salt basin. First commercial production started in 1980 from this field. The field has gone through different development phases in its 30 years of history prior starting tertiary recovery phase by polymer flooding. This field scales Polymer flood project comprising 27 patterns as Phase-1 covers about one third of the total field IOIP (initial oil in place). It is worth mentioning that whole field is under water flooding and water injection was going on prior to initiation of Polymer flood in all these 27 injectors. Further extension in phases to full field polymer flooding is under evaluation. Till now this Polymer flood project has successfully completed 3 years of good performance contributing to significant oil gain. This paper describes briefly about the principles involved in polymer flooding, planning of this polymer flood project, field implementation and field examples of polymer response. In addition, a few practical aspects of managing key issues in polymer flooding like- fracture growth in injectors, shear degradation of polymer solution, pattern conformance and back produced polymer has been covered in this paper.

Historical and recent observations in polymer floods: An update review

“…As mentioned earlier, productivity losses have not been reported in most polymer floods except for Bohai Bay (27 injectors), Sleepy Hollow Reagan Unit (10 injectors) and Marmul (27 injectors) large/ commercial scale polymer floods (Choudhuri et al, 2014;Christopher et al, 1988;Luo, Zhao & Branch, 2011;Thakuria et al, 2013;Xiaodong et al, 2011). Mangala Field, India (Kumar, P., Raj., R., Koduru, N., Kumar, S., & Pandey, A., 2016) and Patos-Marinza, Albania (Bankers, 2016;Carss, 2014;Jacobs, 2015) are also recent large polymer floods but there is a lack of information documenting polymer production and/ or possible productivity losses.…”

“…(a) Estimated from polymer production concentration ( Figure 12, Thakuria et al, 2013) (b) Estimated from Manichand and Seright, 2014 (Figures 6 & 8) and from Delamaide et al, 2016 (Fig. 9) Field, Country Comments Polymer Conc.…”

“…Finally, Haynes, A. K., Clough, M. D., Fletcher, A. J. P., & Weston, S., (2013) reported that the rate at which fracture growth occurred was unknown. Choudhuri et al, 2013;Choudhuri et al, 2014;Koning and Mentzer, 1988;Shuaili et al, 2012;Thakuria et al, 2013;Zwaan and Valdez, 2015). This field was discovered in 1956 and started commercial production in 1980.…”

“…At least 50% of production wells have seen a reduction (5% to 40%) in total liquid rates and reaching more than 50% in some producers. This drop in total liquids (with minimal to no oil gain) corresponds with the high polymer production (>500 ppm) through high permeability streaks and/or fractures (Choudhuri et al, 2013;Thakuria et al, 2013). Strategies to partially restore well productivity include well stimulation with solvents and its combinations with xylene and diesel (Choudhuri et al, 2013).…”

Simulation of Polymer Injection under Fracturing Conditions - A Field Pilot in the Matzen Field, Austria

“…Hence, generation of fractures and injection above the FPP has been suggested (e.g. Seright et al 2011, Moe Soe Let et al 2012, Thakuria et al 2013, Haynes et al 2013 for maintaining or improving the injectivity.…”