Abstract: The Qigu reservoir of District No. 9(4) is characterized by high viscosity, high acid value, high colloid content, low wax, low freezing point, low sulfur, low asphaltene content and sensitive viscosity?temperature relationship. With the continuous extension of areas of the heavy oil reservoir development and the deepening of degree of development in District No. 9 (1?5), the property of in?situ crude oil has changed to a greater degree in different recovery stages. For instance, the oil viscosity, density, freezing point, colloid and asphaltene relative contents are all higher, and solution gas?oil ratio is lower. These could directly influence the percolation nature of in?situ multiphase flows, hence finally impact the recovery percent of the heavy oil reservoir in this area