About 60-70% of oil cannot be produced using conventional technologies (for instance, waterflood) and remains in the subsoil. Chemical flooding technology based on injection of alkali, surfactant, and polymer (ASP) into the formation is a technology that makes it possible to recover residual oil from the subsoil. This technology makes it possible to produce up to 30% of additional oil remaining in the formation. SPD executes a pilot APS injection project on the Salym group of fields.
ASP flooding is an improved enhanced oil recovery technology as compared to conventional waterflood. It uses substances that reduce interfacial tension (alkali and surfactant) and substances enhancing oil mobility (polymer). These three substances are injected into formation through a grid of injectors after the conventional waterflood has already been completed. Surfactant reduces capillary strength that retains oil in small rock pores during waterflood, while polymer increases flooding coverage and efficiency of oil displacement at microscopical level. Joint usage of surfactant and alkali makes it possible to increase formation oil mobility, while polymer increases oil displacement area vs. conventional waterflood. As a result of impact by surfactant and alkali, the oil that proceeds to producers is displaced more efficiently. In doing so, total amount of fluid produced remains the same, while the amount of produced water decreases and the amount of oil increases.
SPD has been studying this technology since 2008. Together with shareholders – Shell and Gazprom neft – the company has performed large-scale work to determine the optimum ASP composition which must correspond to composition of formation water and rock mineralogy as much as possible. To this end, series of laboratory experiments have been conducted to create conditions which are as close to those of specific deposits as possible. After that, SPD specialists have verified the efficiency of the composition selected on a core recovered from the reservoir. Pursuant to the results of laboratory experiments, a model of reservoir with relevant properties was created, which SPD used to conduct a single well practice test in 2009. The results of field studies proved to be fairly encouraging. Following chemical flooding, displacement of 90% of residual oil was noted, which is regarded as the technical limit. The results acquired in the course of field tests made it possible for the company to generate a project for ASP application on the Salym group of fields, the pilot phase of which was approved by SPD shareholders.
SPD is currently performing preparatory work including preparation of project documents, selection of contractors and vendors, and contracting thereof. The company has completed construction of well pad for ASP wells. In 2014, SPD is planning to start well drilling and construction of infrastructure facilities required for execution of the project: pipeline, APS unit, and emulsion breaking module.
Further progress of the project depends on the results of pilot phase which SPD is planning to execute in 2013-2015. It is only pursuant to the results obtained in the pilot phase that SPD shareholders will make the decision to execute full-field application of ASP on the Salym group of fields. In case ASP proves successful on the Salym oilfield, this technology can be replicated on other fields in the region since their properties are similar to those of the formations in SPD license areas.