An Improved Steam Injection Model with the Consideration of Steam Override

Abstract

-The great difference in density between steam and liquid during wet steam injection always results in steam override, that is, steam gathers on the top of the pay zone. In this article, the equation for steam override coefficient was firstly established based on van Lookeren's steam override theory and then radius of steam zone and hot fluid zone were derived according to a more realistic temperature distribution and an energy balance in the pay zone. On this basis, the equation for the reservoir heat efficiency with the consideration of steam override was developed. Next, predicted results of the new model were compared with these of another analytical model and CMG STARS (a mature commercial reservoir numerical simulator) to verify the accuracy of the new mathematical model. Finally, based on the validated model, we analyzed the effects of injection rate, steam quality and reservoir thickness on the reservoir heat efficiency. The results show that the new model can be simplified to the classic model (Marx-Langenheim model) under the condition of the steam override being not taken into account, which means the Marx-Langenheim model is corresponding to a special case of this new model. The new model is much closer to the actual situation compared to the Marx-Langenheim model because of considering steam override. Moreover, with the help of the new model, it is found that the reservoir heat efficiency is not much affected by injection rate and steam quality but significantly influenced by reservoir thickness, and to ensure that the reservoir can be heated effectively, the reservoir thickness should not be too small.Résumé -Un modèle amélioré d'injection de vapeur prenant en compte la surcharge de vapeur -La différence de densité entre la vapeur et le liquide lors de l'injection de vapeur humide conduit toujours à un débordement de vapeur, en d'autres termes, la vapeur s'accumule sur le dessus de la zone de production. Dans cet article, l'équation pour le coefficient de surcharge de vapeur a d'abord été établie sur la base de la théorie de la surcharge de vapeur de van Lookeren, puis le rayon de la zone de vapeur et la zone de fluide chaud ont été dérivés selon une distribution de température plus réaliste et un bilan énergétique dans la zone de production. Sur cette base, l'équation d'efficacité thermique du réservoir en tenant compte de la surpression de la vapeur d'eau a été développée. Par la suite, les résultats prévus par le nouveau modèle ont été comparés à ceux d'un autre modèle analytique et à CMG STARS (un simulateur numérique à réservoir commercial reconnu) pour vérifier la précision du nouveau modèle mathématique. Enfin, sur la base du modèle validé, nous avons analysé les effets du taux d'injection, de la qualité de la vapeur et de la densité du réservoir sur l'efficacité thermique du réservoir. Les résultats montrent que le nouveau modèle peut être simplifié par rapport au modèle classique (modèle de Marx-Langenheim) à condition que la 2017 DOI: 10.2516 This is an Open Access article dist...

Effects of Solvent Properties and Injection Strategies on Solvent-Enhanced Steam Flooding for Thin Heavy Oil Reservoirs with Semi-Analytical Approach

“…2b), after the cold steam condensate reaches the production well (steam condensate-producing stage). The pressure inside the steam zone is constant during all stages [16,17]; 2. an interface model proposed by van Lookeren [18] has been used widely to describe the shape of the steam front without considering heat loss. It is a reasonable model for the steam-flooding process in thick reservoirs; however, it is not applicable for thin reservoirs with considerably more severe heat losses to the understrata and overburden.…”

“…It is a reasonable model for the steam-flooding process in thick reservoirs; however, it is not applicable for thin reservoirs with considerably more severe heat losses to the understrata and overburden. Thus, according to the reservoir numerical simulation results, the geometries of the steam and water fronts are assumed to be a cosine curve and circular shaped, respectively; 3. all mobile oil is assumed to be displaced by the steam and hot water; thus, only residual oil is left in the steam and hot water zone; 4. the gas-phase solvent can move freely in the hot water zone owing to the high temperature and low oil saturation [17,19], whereas the cold steam condensate may block the diffusion of solvent into the heavy oil. By investigating VAPor-EXtraction (VAPEX) experiments, Das and Butler [20] proposed that the contact area of the solvent and crude oil was directly related to the rate of the mass transfer, as indicated in Figure 3a.…”

An integrated model for productivity prediction of cyclic steam stimulation with horizontal well

“…In addition, their model ignored the effect of steam overlay was not taken into account . In recent years, He et al improved the formation heating model by considering the nonisothermal distribution of formation temperature and the effect of steam overlay effect. Zhou et al set up a formation heating model for superheated steam injection with vertical wells, which was further improved by He et al who adopted a more realistic formation temperature distribution of superheated steam injection.…”

“…For instance, for vertical wells, a part of heat loses to the boundary and the remaining part is used for heating the formation when the steam reaches the bottomhole. However, for the horizontal wells, the heating process is divided into several processes based on whether the frontier of heat area reaches boundary or not . More importantly, as the steam flows along the horizontal wellbore, the steam temperature, pressure, and quality always change with horizontal well length .…”

A New Mathematical Model For Heat Radius of Cyclic Superheated Steam Stimulation with Horizontal Wellbore

“…The authors and their team have done some research on the mathematical model of steam soaking heat radius and productivity prediction for heavy oil reservoirs [24], the effect 2 Mathematical Problems in Engineering of steam override [25], mechanism of heavy oil recovery by cyclic superheated steam stimulation [26], factors affecting the performance of cyclic superheated steam stimulation [27,28], the mathematical model of the heat radius for the superheated steam stimulation with vertical well [29], and the mathematical model to calculate thermophysical parameters of horizontal wellbore in the superheated steam injection [30]. Based on previous research, the authors begin to predict the heat radius of cyclic superheated steam stimulation with horizontal wellbore that is applied in K oilfield, Kazakhstan.…”