Use of Foams EOR in Piedemonte Fields - A Successful Mechanism to Improve Gas Sweep Efficiency in Low Porosity and Naturally Fractured Reservoirs

Abstract

This paper presents the development and successful implementation of the Foams technology as an effective EOR mechanism to improve the sweep efficiency of the gas injection in the Piedemonte fields. It also shows the process of optimization of the technology to adapt it to the Piedemonte operating conditions, which is based on massive hydrocarbon gas reinjection, and how this process led us to be at a state of the art position in this technology. The methodology to adapt and further develop the foam EOR technology in Piedemonte was based on the Capital Value Process (CVP). It starts with a screening exercise, passes through a technical assurance including applicability, fluids compatibility, modeling and coreflooding tests at reservoir conditions. Finally, the specific solution is implemented in the field to confirm effectiveness. Initially the foams were deployed using the conventional Surfactant Alternating Gas (SAG) technique, but then the technology was optimized to better suit the operating conditions of the fields, and the last interventions have been done dispersing the foamer chemical in the gas stream. This technology has been implemented in most of the fields in the Piedemonte and has proved success since the early implementation pilots in 2011. Implementation started in the Cusiana field, which is a matrix dominated system, and then moved to the naturally fractured and low porosity reservoirs located in the Recetor and Floreña fields. In all the cases, the implementation of foams has rendered positive results reflected in incremental oil production and flattening of the Gas Oil Ratio (GOR) at the influenced producer wells. The new developed dispersed Foams technology has been as effective as the conventional SAG in the jobs performed so far, with the advantages of requiring less surface equipment, and water consumption than SAG jobs. Benefits from Foams implementations so far add up to about 0.65 MM STB. Main conclusions from this project are i) The foams EOR technology is fully applicable in the Piedemonte fields to improve the gas sweep efficiency and increase final oil recovery. ii) A new foam deployment technique based on the injection of the foamer chemical dispersed in the gas stream was developed, and proved effectiveness at the field. The work is innovative in two ways: i) Effectiveness of foam as a technology to improve gas sweep efficiency in naturally fractured dominated systems was proved. ii) A new foam deployment technique based on the injection of the foamer chemical dispersed in a non-condensable gas stream was developed. Also this new foam EOR technique can be extrapolated to any other field operated under gas injection.