Numerical simulation of fire flooding for heavy oil reservoirs after steam injection: A case study on Block H1 of Xinjiang Oilfield, NW China

Abstract

With the 3a pilot area in Block H1 of Xinjiang Oilfield as an example, a basic model for accurate numerical simulation of fire flooding is established combining with physical simulation and field performance, after oil components are divided reasonably, high temperature combustion formula is defined. This model is used to trace and simulate the fire flooding in Block H1. The main results are as follows: (1) secondary water generated after steam injection is mostly displaced by flue gas during initial combustion phase, and only a small fraction works for limited wet combustion; (2) the flooded reservoirs, from the gas injection well to the production well, are divided into burnt zone, fire wall, coking zone, high temperature condensed zone (added newly), oil bank, and residual oil zone; and (3) the fire flooding for reservoir after steam injection, unlike original reservoir, experiences a process of oil bank building and migration featuring “pit filled and bank built”, with bank shape related to the performance of adjacent production wells. Moreover, the field experiment indicates that the numerical simulation of fire flooding contributes to the prediction and management of flooding performance. Key words: heavy oil reservoir, fire flooding, numerical simulation, secondary water, oil bank, high temperature condensed zone