Recent Advances in Polymer Flooding in China: Lessons Learned and Continuing Development

Abstract

Summary Polymer flooding is one of the most promising chemical enhanced-oil-recovery (EOR) techniques. It offers a high incremental-oil-recovery factor (IORF), low cost, and wide reservoir applicability. The first large commercial polymer-flooding application began in Daqing Oil Field and remains the largest polymer application in the world. However, encouraged by the success of previous field applications and new findings regarding the viscoelasticity of polymers in the reduction of residual oil saturation (ROS), high-concentration high-molecular-weight (MW) polymer-flooding (HCHMW) field tests have been conducted in many oil fields in China. Although some of these field tests in Daqing are well-documented, subsequent progress has seldom been reported. Moreover, recent references about the latest polymer-flooding applications in China reveal that HCHMW has only a limited application in Daqing. This is not in agreement with previous reports and expectations, especially given that viscoelasticity has been drawing increased attention. This paper explains why HCHMW is not currently widely used. New types of amphiphilic polymers are also field tested in China. Lessons learned from polymer-flooding practices in offshore reservoirs, heavy-oil reservoirs, and conglomerate reservoirs are given to help reduce risks and costs of polymer flooding in the low-oil-price era. EOR techniques in post-polymer-flooding reservoir field tests are also compared. In addition to providing useful information for engineers, this paper helps clarify some misconceptions—such as injecting the most viscous polymer possible—in polymer-flooding implementations, according to polymer-flooding practice in China. Annual oil production using polymer flooding as well as polymer utility factors (UFs) are given. Various technical parameters, such as polymer slug, viscosity, IORF, oil-increase factor (OIF), and water-cut decrease, are provided to better understand polymer-flooding evaluation as well economics.

Critical Review of Polymer Flooding in Daqing Field and Pelican Field: Case Studies of the World’s Largest Polymer Flooding in Light and Heavy Oil Reservoirs, Respectively

“…Oil production with polymer flooding and polymer powder as used in Daqing is shown in Figs. 4 and 5, respectively [55].…”

Application and Optimization of the Rheological Model for a Hydrophobically Associating Dendrimer Polymer

“…where N 1 is the first normal stress difference, Pa; G is the elastic modulus, Pa; and G" is the viscosity modulus, Pa. We refer to the expression of the dynamic modulus in reference [29] as Formula (6).…”

“…However, complex reservoir conditions necessitate higher requirements for the performance of polymer solution applications, thus promoting the rapid development of polymer synthesis technology [5]. Currently, the synthesis of polymer flooding agents mainly focuses on improving the performance of the solution by chemically modifying the molecular structure of the polymer and introducing functional groups to produce functional polymers [6][7][8]. More recent studies focus on the synthesis and characterization of the hydrophobic groups linked to polymers of dendritic structures [9].…”

Pressure Modification or Barrier Issues during Polymer Flooding Enhanced Oil Recovery

“…The mechanism illustrated in Figure 5 may be particularly relevant to the Daqing polymer flood. At Daqing, the layers are relatively thin, and few problems have been observed with either injectivity or early polymer breakthrough in production wells [6,[36][37][38][39][40][41][42][43]. These observations 6 Geofluids are difficult to rationalize using conventional simulations without fractures, particularly for the Daqing cases where 150-300 cp polymer solutions were injected to recover ~10 cp oil.…”

“…Daqing has been the largest polymer flood in the world since 1996. Many papers are available that describe this project [6,[36][37][38][39][40][41][42][43]. The oil viscosity associated with the main polymer flood was about 10 cp at 45 °C.…”