Use of Cross-Linked Polymer Systems to Improve Volumetric Sweep Efficiency and Alternative Full Field Development Strategy for a Mature Waterflooding Optimization Processes - Dina Cretaceous Field Case

摘要

The Dina Cretaceous field, operated by Ecopetrol S.A., is located in the Upper Magdalena Valley (UMV) Basin in Colombia. The field discovered in 1969, reaching maximum primary oil rate of 6,500 BOPD in May 1980. Secondary recovery mainly by peripheral water injection started in 1986, achieving a maximum production of 9,850 BOPD in January 1988. Subsequently, water production has increased rapidly accompanied by declining oil production, due primarily to reservoir heterogeneity and an unfavorable mobility ratio. The oil recovery factor as of October 2017, as a percentage of OOIP, is estimated to be approximately 33% at a current water cut of about 97%. Ecopetrol S.A in 2009, began to look for new development strategies that would allow optimizing the oil recovery for this asset. Several IOR/EOR technologies were screened to reduce water production and increase sweep efficiency. Polymer gels ("Conformance treatments"), polymer flooding and cross-linked polymer also known as Colloidal Dispersion Gels (CDG) are some of the technologies most commonly used during the last few decades for this purpos. Based on screening study, detailed production and injection data analysis, water channeling, reservoir heterogeneity, adverse mobility ratio, laboratory evaluation and simulation results, the cross-linked polymer systems (CDG) were implemented in four patterns between 2011 and 2015. This would allow to increase the volumetric sweeping efficiency both for mobility control, in-depth conformance control and leading to viable project both technically and economically. This paper presents the implementation and results of the injection of cross-linked polymer systems in the Dina Cretaceous field. A summary of the maturation process is presented, from conceptual design, experimental evaluation, engineering analysis, numerical simulation, pilot execution, process monitoring and field expansion strategy, as well as the results obtained in the pilot. The results of the pilot were satisfactory both technically and economically and lead to a new development plan for the field. This new plant is focused on the optimization of the waterflood, pattern reconfiguration, infill drilling, selective injection, and improving the sweep efficiency through the injection of cross-linked polymer across the field in 11 more patterns.