Analysis of a feasible field THAI pattern by the derivation of scaling criteria and combustion experiments

Toe-to-heel air injection (THAI) process is considered as a potential enhanced oil recovery (EOR) method for heavy oil production. For physical simulation of THAI process in laboratory conditions, the simplified scaling criteria of THAI process were derived and a novel three-dimensional cylindrical apparatus was used to construct the new THAI pattern in this study. Equation analysis and dimensional analysis (Buckingham π-theorem) were applied to deduce the whole dimensionless groups, and sensitivity of the coefficients described with their distortion coefficients were used to obtain the influential weights and the simplified scaling criteria. STARS module in Computer Modeling Group (CMG) was used to verify the feasibility of the THAI pattern by two models, which represent the reservoir prototype and the 3D apparatus respectively. With an effective simulation of experimental results, a reasonable data set was obtained, and then those values were upscaled for simulation of field THAI process by the simplified scaling criteria. The experiment results showed that the horizontal well was well protected by a slant distribution of coke zone and the other parameters about oil production (such as the high temperature swept volume, oil production rate and recovery) were still satisfactory. The similarity of variation process of temperature field, oil saturation distribution and production performance between the laboratory results and THAI simulation in reservoir prototype showed the validity of the scaling criteria and indicated that a feasible field THAI process with a large combustion chamber upon horizontal well can be predicted to achieve.