A Methodology for Screening and Ranking of Reservoirs for Light Oil Air Injection Implementation

Abstract

A great portion of the produced oil currently comes from mature fields, reason why the increase in oil production of current reservoirs is the main objective of oil companies. Thermal enhanced oil recovery processes have been studied, implemented and improved over the years. In the last decade there has been significant interest in the light oil air injection (LOAI) process since the successful implementation of the process known as High Pressure Air Injection in the Buffalo Field (USA), which is a variation from the air injection process in light oil, applicable to deep reservoirs with low permeability and porosity. Proof of this are the West Hackberry Field (USA), more than five commercial projects along the Willinston Basin (USA) and recently a pilot in the Zhong Yuan Field (China). Additionally, feasibility studies have also been initiated and performed in Mexico, Argentina and Colombia. This article proposes screening criteria for the selection of potential light oil reservoirs to be candidates for air injection, as well as a general methodology for the prioritization of the reservoirs with the highest LOAI implementation potential. Said methodology employs screening criteria, analogies and numerical simulation. The first part goes beyond the binary screening by assigning a weight to each one of the criteria, therefore resulting in a numerical ranking. For the analogies the reservoirs in which the technology has already been applied are grouped in four group types, against which the field on evaluation is compared. There is also a numerical simulation in 1D – 2D, where the injectivity with or without pressurization is evaluated, as well as the displacement stability. Additionally a multi-criteria evaluation method is used to select the best candidate.