Feng, Qi-hong (China U. of Petroleum East) | Wang, Sen (China University of Petroleum East China) | Wang, Shoulei (Shengli Oilfield Geological Scientific Research Institute) | Wang, Yanzhong (Shengli Oilfield Geological Scientific Research Institute) | Chen, Depo
Pressure Index (PI) is a significant parameter, which is commonly used for profile control project design and injection well performance analysis in China, due to its simple and economical application. However, PI can only reflect the current fluid flow capacity and present heterogeneity of the formation. It's well known that the formation structure will change distinctly after long-term waterflooding for the pressure variation and its in-situ heterogeneity, during which thief zones or high-conductive channels may come into being. Therefore, PI can not take into account the dynamic change of the formation structure, and thief zones can not be identified by PI. As a result, efficiency of profile control decision might be not as good as expected.
The objective here is to develop a new parameter which can identify thief zones easily and to verify its validity from both the synthetic model and the pilot test. Dimensionless Pressure Index (DPI) is established on the basis of PI, which not only takes the transformation of fluid flow capacity into consideration, but also keeps its initial advantages—simple and low-cost. Synthetic models are used to validate the methodology. And the pilot test shows that identification of thief zones by DPI is in good accordance with other approaches. Moreover, DPI can also be applied to determine the severity of the thief zone for a certain oilfield. Another advantage of DPI is that the combination of PI and DPI will make the profile control project design more effective and improve waterflooding surveillance. This approach has been applied successfully in several China oilfields.