Grid upscaling is to keep the reservoir physical properties and seepage characteristics of the two models as same as possible before and after upscaling. Thus, the model after upscaling can achieve the same development effect as before upscaling. The permeability is upscaled by harmonic average and arithmetic average. It's found that the relationship curve between recovery degree and water cut after upscaling is different from that before upscaling. Based on reservoir engineering theory, a functional relationship between slope and intercept of Kro/Krw⁃Sw relationship curve and slope and intercept of water⁃oil ratio and recovery relationship curve is derived. Therefore, the phase permeability curve after upscaling can be deduced back. It's found that there is a linear relationship between the displacement distance of the phase permeability curve and the intercept of the fitting line of the water⁃oil ratio curve and the recovery degree curve. The displacement distance of the phase permeability curve can be calculated. The phase translation law is verified by using actual oilfield data. The error of water⁃oil ratio and recovery degree curve between after translation and before coarsening is 3.16%, and the precision is high.

At present, due to active edge water in BQ57 area of target oilfield, the reserve recovery is low. Therefore, it is necessary to study the remaining oil in BQ57 area to ensure good results in thermal recovery process. The distribution law of remaining oil in vertical and plane of layers III 1 and 3 in BQ57 area is studied. The total remaining oil is 43.22 ×104 t. In the vertical, the geologic reserve of layer Ⅲ11 is 17.76×104 t. The remaining geological reserves are 14.72×104 t. The degree of reserve recovery is 17.19%. The geological reserve of layer III12 is the smallest, which is 5.79×104 t. The remaining oil is also less, which is 4.86×104 t. The degree of reserve recovery is 16.09%. The remaining oil in layer III31 is the largest, which is 15.4×104 t. The degree of reserve recovery is 11.20%. The remaining oil in layer III32 is 8.26 ×104 t and the degree of reserve recovery is 6.17%. On the plane, the proportion of remaining geological reserves channel is 52.87% in underwater distributary. Because its distribution area is largest, the proportion of remaining oil is the highest and the value of reserves abundance is the highest. The proportion of remaining oil in front sand sheet is 44.98%. Its value of reserves abundance is also higher. The latter adjustment of well pattern needs to be combined with the productivity potential of a single well, the underwater distributary channel and front sand sheet should be given priority in the adjustment of well pattern.