Survey and Data Analysis of the Pilot and Field Polymer Flooding Projects in China

Abstract

Enhanced oil recovery (EOR) processes are regarded as important methods to recover remaining oil after primary and secondary recovery. It is important to select the most appropriate EOR process among the possible techniques for a candidate reservoir. Therefore, EOR screening criteria have been constructed using available EOR data sets and serve as the first step to compare the suitability of each EOR method for a particular reservoir. Most screening criteria for polymer flooding are based on data sets from EOR surveys published biannually by the Oil & Gas Journal. These surveys missed significant polymer flooding parameters such as formation water salinity and hardness, polymer types and molecular weight, polymer concentration, reservoir heterogeneity, and so on. All of these topics are covered in this paper with data from relevant literature and records provided by oil companies in China.Polymer flooding has been widely applied in China for over 20 years and a large number of pilot and field projects have been conducted. These projects include important information to quantify the development of polymer flooding as an EOR method. Nevertheless, most of them have been published in Chinese, and are not accessible to the global research community due to the language barrier. This paper represents an effort to collect all relevant information of polymer flooding from available Chinese publications and reports from all of the major oil companies in China. The primary objectives of this survey is to reveal EOR advances, to trace the development of the polymer flooding EOR methodology in China, and to benefit EOR worldwide.This project collected information on 55 polymer flooding projects after reviewing nearly 200 publications in Chinese, including 31 pilot projects and 24 field projects from 1991 to 2014. A data set was constructed by collecting all relevant information for polymer flooding. Statistical analyses and graphical methods were used to analyze the whole data set. Box plots combined with violin plots were used to show the distribution and the range of each parameter. By defining and calculating lower and upper limits in box plots, special projects were identified and explained. Scatter plots, which show multiple parameters in one plot, were used to identify significant relationships among different parameters, especially for dependent parameters. This method overcomes some disadvantages of the range method, which is traditionally used for EOR screening. For example, using polymers with high concentration in low salinity reservoirs can lead to higher incremental oil recovery than in high salinity ones, and lower permeability usually correlates with the use of polymers with lower molecular weight. However, the traditional range method cannot show this relationship. Finally, comprehensive screening criteria for polymer flooding were updated based on information revealed in the field application projects.

Historical and recent observations in polymer floods: An update review

“…Sheng et al (2015) and Zhang, Y., Wei, M., Bai, B., Yang, H., & Kang, W., (2016) suggested the applicability of polymer flooding for reservoirs with crude oil viscosities up to 150 cP and 285 cP, respectively. This viscosity range clearly contradicts technical and economic feasibility of polymer floods in viscous oils and/or screening criteria proposed by Mogollón and Lokhandwala (2013), Carss (2014), Renouf (2014) and Delamaide et al (2014a).…”

“…However, Sheng et al (2015) did not present solid arguments to discard the applicability of polymer flood technology in heavy oil reservoirs. In the case of Zhang et al (2016), the proposed criteria for crude oil viscosity (up to 285 cP) to consider polymer injection was based exclusively on the experience in China, including 24 field scale projects (i.e. Bohai Bai and Daqing Fields).…”

“…It is clear that most projects (highlighted with the dashed line rectangle) have been implemented in reservoirs with μo and K below 100 cP and 1 Darcy, respectively. However, Bohai Bai "A", Patos-Marinza and Pelican Lake are three of the few ongoing commercial scale polymer floods in reservoirs with viscosities above the proposed values by Sheng et al (2015) and Zhang et al (2016). Hence, crude oil viscosity should not be used as the only reference to discard the applicability of polymer flooding in a given reservoir based on ongoing commercial projects.…”

“…Zhang, Y., Wei, M., Bai, B., Yang, H., & Kang, W. (2016) recently presented a survey and data analysis of polymer floods (pilot and commercial) projects implemented in China. This study includes 55 (31 pilots and 24 field scale) projects from 1991 to 2014.…”

“…However, despite numerous successes and encouraging results reported in multiple field experiences , the number of large-scale or commercial floods is still considered relatively low except in Canada (Renouf, 2014) and China (Zhang, Y., Wei, M., Bai, B., Yang, H., & Kang, W., 2016). Examples of other countries reporting large scale (>10 injectors) or commercial polymer floods include Albania (Bankers, 2016), Argentina (Buciak, Sancet & Del Pozo, 2015) and Oman (Choudhuri et al, 2014).…”