Improve The Extra Heavy Oil Steam Soaking Effect Research

Xinglong Group oil layers and Guantao oil layers of Du84block in Shu1area, Liaohe oilfield, are extra heavy oil reservoirs. Steam stimulation has been employed to develop these two reservoirs since1997and the production output rises steeply to more than120million tons per year. Affected by the development mode of steam stimulation and the oil’s property, period production output decreases gradually, the stimulation effect becomes poorer and the cost to produce one ton oil rises after entering the late period of cyclic steam stimulation. Under the obscure circumstance of how to convert the production mode for the next step to keep thermal production, it’s imperative to seek applicable technique measles to improve the steam stimulation effect of late cyclic period and enhance degree of reserve recovery in the steam stimulation period.In this paper, beginning with reservoir geological conditions and exploitation mechanism of extra heavy oil and associate with real production practice, reservoir engineering methodology is employed to study the production feature and regular pattern of extra heavy oil reservoir steam stimulation. We sum up the four following factors which affect the result of steam stimulation in late cyclic period:high degree of reservoir recovery with low oil saturation in the near well bore formation, more water storage subsurface formation with low thermal utilization ratio。deplete seriously underground lead to the decline of formation pressure, strong reservoir heterogeneity lead to intensify the interval discrepancy. After the theory is studied and the dynamic monitoring data is analyzed. we initiate to develop three kinds of production modes, which arc multi-well integral steam stimulation, intermittent steam stimulation and more production to one injection, and technology measures such as improving injection profile in high temperature condition and travail compound steam stimulation. What have been done improved the steam stimulation effect of extra heavy oil reservoir in late period and enhanced the recovery rate in steam stimulation stage.