A top-injection bottom-production cyclic steam stimulation method for enhanced heavy oil recovery

摘要

A novel method to enhance oil production during cyclic steam injection has beendeveloped. In the Top-Injection and Bottom-Production (TINBOP) method, the wellcontains two strings separated by two packers (a dual and a single packer): the shortstring (SS) is completed in the top quarter of the reservoir, while the long string (LS) iscompleted in the bottom quarter of the reservoir. The method requires an initial warm-upstage where steam is injected into both strings for 21 days; then the LS is opened toproduction while the SS continues to inject steam for 14 days. After the initial warm-up,the following schedule is repeated: the LS is closed and steam is injected in the SS for 21days; then steam injection is stopped and the LS is opened to production for 180 days.There is no soak period.Simulations to compare the performance of the TINBOP method against that of aconventional cyclic steam injector (perforated across the whole reservoir) have beenmade. Three reservoir types were simulated using 2-D radial, black oil models: Hamaca(9????API), San Ardo (12????API) and the SPE fourth comparative solution project (14????API).For the first two types, a 20x1x20 10-acre model was used that incorporated typical rockand fluid properties for these fields. Simulation results indicate oil recovery after 10 years was 5.7-27% OIIP withTINBOP, that is 57-93% higher than conventional cyclic steam injection (3.3-14% OIIP).Steam-oil ratios were also decreased with TINBOP (0.8-3.1%) compared to conventional(1.2-5.3%), resulting from the improved reservoir heating efficiency.