TX 75083-3836, U.S.A., fax 01-972-952-9435.
AbstractOf the oil produced by Jinzhou Oil Company, Liaohe Petroleum Corporation, 72.7 percent is heavy oil, mainly recovered by cyclic steam injection method. As for the major pay zone, Block Jin-45 and Block Jin-7, the average number of huff-and-puff cycles is as high as 8.9, and average fluid pressure is dropped to 4 MPa at the depth of 1000 meters. Non-uniform production worsens the situation: Oil/steam factor is dropped to 0.49; Natural reduction rate is as high as 46%; and the profit is decreasing year by year. To maintain a sustainable and steady increase in oil production under the current situation, experiments of combined fuel gas and steam cyclic injection were first carried out on heavy oil wells, taking into account the current situation of our oilfield and the development history of similar oil fields in and outside China. After nearly one year's field experiment, identifiable results have been discovered, such as less air pollution resulted from the emitted gas, better protection of the casing, fewer heatinsulation pipes, more modification of steam injection profile, higher production rate, shorter water drainage period, and greater reduction of operation cost. By the end of year 1999, 599448 cubic meters of fuel gas has been injected into six wells in Block Jin-7 and Block Jin-45; 3350 cubic meters of steam was saved and 1964 tons of incremental oil was obtained. The social and economical efficiency was obvious.