Polymer-Flooding-Pilot Learning Curve: Five-Plus Years' Experience To Reduce Cost per Incremental Barrel of Oil

Abstract

Summary This paper deals with the learning curve of a five-plus-year polymer-flooding pilot conducted in a mature waterflood that includes, for example, several works related to injector and producer wells and reservoir management. The scope of this paper is to describe the learning curve during the last 5 years rather than the reservoir response of the polymer-flooding technique; focus is on the aspects related to reduce cost per incremental barrel of oil for a possible extension to other waterflooded areas of the field. Diadema oil field is in the San Jorge Gulf basin in the southern portion of Argentina. The field is operated by CAPSA, an Argentinean oil-producer company; it has 480 producer and 270 injector wells (interwell spacing is 250 m on average). The company has developed waterflooding over more than 18 years (today, this technique represents 82% of oil production in the field) and produces approximately 1600 m3/d of oil and 40 000 m3/d of gross production (96% water cut) with 38 400 m3/d of water injection. The reservoir that is polymer-flooded is characterized by high permeability (average of 500 md), high heterogeneity (10 to 5,000 md), high porosity (30%), very stratified sandstone layers (4 to 12 m of net thickness) with poor lateral continuity (fluvial origin), and 20 °API oil (100 cp at reservoir conditions). Diadema's polymer-flooding pilot started in October 2007 on five water injectors (it includes 13 injectors today) with an injected rate of 1000 m3/d (today, 2000 m3/d). Polymer solution is made with produced water (15,000 ppm brine) and 1,500 ppm of hydrolyzed polyacrylamide polymer reaching 15- to 20-cp fluid-injection viscosity. Oil-production rate from the original “central” producers (wells that are aided with 100% of polymer injection) has increased 100% at the same time as average reduction in water cut is approximately 15%. The main aspects presented in this work are depth profile modification with crosslinked gel injected along with polymer, use of “curlers” to regulate injection in multiple wells with one injection pump without shearing the polymer, and an improved technology on producer wells with progressing-cavity pumps to decrease shut-in time and number of pump failures. The plan for the future is to extend this project to other areas with the acquired knowledge and to improve different aspects, such as water quality and optimization of polymer plant operation. These improvements will allow the company to reduce operating costs per incremental barrel of oil.

Evaluation of Polymeric Materials for Chemical Enhanced Oil Recovery

“…These advantages have been supported by the successful polymer flooding of the Daqing oil field (China), showing a remarkable incremental oil recovery of 22.3% of the original oil in place (OOIP) and a consistent decrease of water production (i.e., water cuts) during 12 years of polymer flooding [9,140,141]. Another example is the polymer-flooding project at the Diadem viscous oil reservoir, San Jorge Gulf Basin (Argentina), which has also shown a significant increase of oil production rates (100% increase) and an average reduction of the water cut of 15% after five years of polymer injection [142]. Likewise, polymer flooding has been successfully applied for years at the Shengli Oilfield (China), which has rendered significant increases of the oil production rates, important reductions in water cuts, and significant incremental oil recovery; for more detail, readers are referred to reference [8].…”

“…From the technical experience gathered from field applications worldwide [9,17,22,126,142,144], one can summarize several key aspects that must be considered during the design of polymer flooding for field applications:…”

Historical and recent observations in polymer floods: An update review

“…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). Figure 1 shows the general location of pilot and large/ commercial (> 10 injectors) polymer flood projects included in this review.…”

Operational Challenges and Monitoring of a Polymer Pilot, Matzen Field, Austria

“…To investigate the effectiveness of alkali/surfactant/polymer, for example, Hernandez et al (2002) and Dijk et al (2010) chose a single-well test. Cheng et al (2012) and Prasad et al (2014) describe interwell tests comprising a production well surrounded by injectors, while Putz et al (1988) used an inverted-five-spot configuration. Multiwell polymer-injection pilots are described by Manichand et al (2013) and Buciak et al (2015).…”