This paper presents a systematical review of the largest Alkaline-Surfactant-Polymer (ASP) flood project in the world, applied to the largest oil field in China. First, reservoir and fluid characteristics are highlighted to understand heterogeneity of the reservoir. Next, project history is summarized, including laboratory studies, pilot tests, industrial-scale tests and fieldwide application. Thirdly, typical ASP flood performance and reservoir management measures from over 30 years’ experience are presented. In addition, performances of ASP flood and polymer flood in the same field, which is also the largest project in the world, are compared.

The Lamadian-Saertu-Xingshugang (La-Sa-Xing) Field in the Daqing Field Complex, located in the north of the Songliao Basin, is the largest oil field in China. The Upper Cretaceous Saertu-Putaohua-Gaotaizi (S-P-G) reservoir has an average porosity of 25% and average permeability of 610 md. The reservoir consists of more than 100 flow units and is characterized by significant heterogeneity both vertically and laterally. Crude oil has an API gravity of 33° and a viscosity of 9 cP at reservoir conditions. The discussed ASP flood project mainly targets high-quality reservoir sands. The field was brought onstream in 1963 with immediate water injection. Crossflow and water-breakthrough became common issues during water injection, calling for a suitable EOR method. ASP Flood was studied in laboratory from 1987-1993, followed by five small-scale pilots from 1994-1999, all being successful with incremental recoveries of ~20% STOIIP. As a result, industrial-scale tests were conducted from 2000-2007, resulting in substantial improvement in production from ~4000 BOPD to greater than 19,000 BOPD. Encouraged by those successes, the ASP project was expanded to fieldwide scale since December 2007, which is the largest ASP flood project in the industry worldwide. By 2021, daily oil production by ASP flood had reached 96,000 BOPD through 9650 wells. The average incremental recovery factor is 20% over waterflood and 8-10% over polymer flood, resulting in ultimate recovery factor of >60%. Zonal injection and profile modification are effective measures to further improve sweeping efficiency. Scaling is the major challenge during the operation of ASP flood, which is mitigated or remediated by adopting weak alkaline ASP, progressive cavity pumps (PCP), scale inhibitor treatment and fracturing stimulation on damaged wells.

The world's largest ASP flood project in the La-Sa-Xing Field proved the fieldwide applicability of ASP flood. The effective reservoir management measures and lessons learned from over 30 years’ experience provide valuable experiences for large-scale ASP flood project in the industry.

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