Experimental Study and Thoughts on Safety and Environmental Protection of Steam Flooding of Horizontal Wells in a Heavy Oil Reservoir.

Abstract

Based on similarity criteria, a scaled physical model was fabricated, containing four horizontal wells and representing one-fourth of an inverted nine-spot steam-flooding pattern. A series of steam-flooding physical simulation experiments were carried out after different types of integral cyclic steam stimulations. Temperature distributions in the model reservoir, overburden, and substratum were measured at intervals. Production performance could be exactly recorded. The spatial temperature distribution of the whole model could be obtained. The phenomena of steam channeling, steam override, and secondary heterogeneity were observed obviously. The results that show steam flooding would cause steam overlap and characteristics of steam channeling during steam flooding after different types of integral cyclic steam stimulation were very distinct. The reservoir would have different temperature fields and different flow resistance because of different integral cyclic steam stimulations. The formation fluid would bypass the place with large flow resistance (low-temperature zone), forming secondary heterogeneity and affecting the displacement effect and thus the development effect. The recovery percent of a heavy oil reservoir developed by steam flooding was low, and it would bring some potential safety risks and problems with environmental protection. The experimental results provide theoretical support for further study of the mechanism of steam flooding.