IMPROVING THE STEAM-ASSISTED GRAVITY DRAINAGE INTEGRAL SIMULATOR TO PREDICT THE TIME OF STEAM BREAKTHROUGH INTO THE PRODUCER

Abstract

One of the main problems for Steam Assisted Gravity Drainage (SAGD) is the risk of steam breakthrough into the producer. A relevant task is to simulate SAGD to predict steam breakthrough. The existing models do not predict many technological parameters, and the integral model, developed earlier, does not consider the risk of a steam breakthrough. In this article, for the first time, an integral model is proposed in a dimensionless form, which considers risk of steam breakthrough and allows calculating all stages of SAGD. The aim of this study is to improve the previously developed SAGD model to calculate the vertical coordinate of the upper boundary of liquid phase level. This has required a system of equations based on mass and heat balances both in the chamber and in the region of liquid phases. The system of equations is represented in dimensionless form. The research methodology involves using an explicit finite-difference scheme to solve this system and to verify the model according to the data by Ya. Yang et al. The nonlinear equation included in the system is solved using Newton’s iterative method. The lowering of the upper boundary of liquid phases’ region means steam breakthrough. The results have provided the dependences of volumetric oil flow rate, the vertical coordinate of the upper boundary of the level of liquid phases and steam-oil ratio on time of process. These results are compared with the production data from the Celtic field with good agreement of the calculated data with the actual data. A fast drop in the upper boundary of the liquid phases region, observed with the data used approximately 100 days after the end of vertical growth of the steam chamber, indicates the risk of steam breakthrough.