Mechanisms of Residual Oil Displacement by Steam Injection

Abstract

A model of one-dimensional steam displacement of residual oil has been developed. The quasi-steady model considers the capillary pressure gradients due to the simultaneous flow of the oil, water, and steam to be the dominant factors in oil bank mobilization. The effects of gravity on steam displacement were also included in the model. Semi-analytical calculations of saturation and pressure distributions are presented to illustrate the mechanisms. It was shown that under most conditions, the Buckley-Leverett displacement velocity is significantly faster than the steam condensation front velocity. This result and conservation of oil mass required the use of the steam condensation front velocity as the characteristic velocity in the problem formulation. An expression for a limiting oil saturation at the steam zone interface was thus derived. Experiments were conducted to examine steam displacement of volatile, partially volatile and nonvolatile nonaqueous phase liquids at a residual saturation of 2.5%. Complete displacement of all low viscosity, partially volatile liquids was observed. Displacement of a high viscosity, nonvolatile oil was not observed. These experiments were in reasonable agreement with the model. Introduction Thermally enhanced oil recovery by steam injection has been demonstrated to be particularly effective in terms of increased resource recovery and overall profitability. Thus, a great deal of analytical, computational, and experimental effort has been placed on the description of the steam displacement process. Due to the extreme complexity of the thermally driven transport process, numerical simulation based on finite differencing has emerged as the primary reservoir level predictive technique. Nevertheless, such techniques lack the necessary spacial resolution to provide the details of the small scale interactions representative of the steam displacement of a multicomponent hydrocarbon liquid, particularly near the condensation front where capillary pressures dominate the multiphase flow process.

Steam-Enhanced Extraction Experiments, Simulations and Field Studies for Dense Non-Aqueous Phase Liquid Removal: A Review

“…The physical displacement is the main important removal mechanism for DNAPL remediation involves volatilization, evaporation, steam distillation and steam stripping [8]. The physical displacement is influenced by steam boiling point.…”

“…The steam was capable in mobilizing DNAPL saturation until the ratio of viscosity of DNAPL and water equal to three. If larger, fingering may occur thus reducing the displacement efficiency [8]. Other factors that can influence the application of steam-enhanced extraction as DNAPL remediation is the porous media properties.…”

Traveling waves in a finite condensation rate model for steam injection

“…Oil displacement by steam drive through a porous medium is a complex physical process that is controlled by the steam condensation process and by viscous and capillary forces (see for instance Stewart & Udell [40] and Wingard & Orr [44]. Following ideas of Shutler [39], we proposed in [7] a one-dimensional model where all complexity is confined to a small transition region in which the condensation occurs and capillary forces act.…”

“…It has an upstream hot threephase (oil, water, steam) flow zone and a downstream cold two-phase (oil, water) flow zone. The upstream and downstream zones are separated by a relatively thin transition region, which is described by a (local) steam condensation/capillary diffusion model based on the ideas of Udell et al [28,40,42]. In the limit of zero capillary forces, the transition region collapses to form a steam condensation front (SCF).…”

The effect of steam quality on the electrical behavior of steam‐flooded sands: A laboratory study

“…In recent years, steam injection has also proven to be an effective technique for removing certain types of nonaqueousphase-liquid contaminants from the near-surface (Stewart and Udell, 1988). Its overall effectiveness as a recovery technique depends in part on how much of the subsurface is treated with steam.…”