Improved Steamflood Analytical Model

Abstract The Jones (1981) steamflood model incorporates oil displacement by steam as described by Myhill and Stegemeier, and a three-component capture factor based on empirical correlations. The main drawback of the model however is the unsatisfactory prediction of the oil production peak: usually significantly lower than the actual. Our study focuses on improving this aspect of the Jones model. In our study, we simulated the production performance of a 5-spot steamflood pattern unit and compared the results against those based on the Jones model. Three reservoir types were simulated using 3-D Cartesian black oil models: Hamaca (9°API), San Ardo (12°API) and that based on the SPE fourth comparative solution project (14°API). In the first two field cases, a 45x23x8 model was used that represented 1/8 of a 10-acre 5-spot pattern unit, using typical rock and reservoir fluid properties. In the SPE project case, three models were used: 23×12×12 (2.5 ac), 31×16×12 (5 ac) and 45×23×8 (10 ac), representing 1/8 of a 5-spot pattern unit. To obtain a satisfactory match between simulation and Jones analytical model results of the start and height of the production peak, the following refinements to the Jones model were necessary. First, the dimensionless steam zone size AcD was modified to account for decrease in oil viscosity during steamflood and its dependence on the steam injection rate. Second, the dimensionless volume of displaced oil produced VoD was modified from its square-root format to an exponential form. The modified model gave very satisfactory results for production performance up to 20 years of simulated steamflood, compared to the original Jones model. Engineers will find the modified model an improved and useful tool for prediction of steamflood production performance.