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Active-polymer attracted increasing interest as an enhancing oil recovery technology in oilfield development owing to the characteristics of polymer and surfactant. Different types of active functional groups, which grafted on the polymer branched chain, have different effects on the oil displacement performance of the active-polymers. In this article, the determination of molecular size and viscosity of active-polymers were characterized by Scatterer and Rheometer to detect the expanded swept volume ability. And the Leica microscope was used to evaluate the emulsifying property of the active-polymers, which confirmed the oil sweep efficiency. Results show that the Type I active-polymer have a greater molecular size and stronger viscosity, which is a profile control system for expanding the swept volume. The emulsification performance of Type III active-polymer is more stable, which is suitable for improving the oil cleaning efficiency. The results obtained in this paper reveal the application prospect of the active-polymer to enhance oil recovery in the development of oilfields.

ABSTRACT: Hasan-Kabir''s model and modified Ansari''s model were used to analyze the pressure drop of two-phase flow in underbalanced drilling (UBD). The mathematical and physical models of UBD were established and solved numerically. The effects of injection rate of gas and liquid and, back pressure on bottom-hole pressure were analyzed. The bottom-hole pressure control procedures were concluded. The computer simulations were validated with data obtained from experiment performed in a full-scale well located at Louisiana State University. The prediction accuracy of two methods was analyzed. The results showed that the error with the Hasan-Kabir model is less than 10%, however the error with the modified Ansari model is less than 5%. Ansari''s model is superior to Hasan-Kabir''s model in predicting pressure. This supplies theoretical support for success in UBD. [Copyright &y& Elsevier]