Study On Evaluation Of Shale Barrier’s Property And Its Breakthrough Methods During SAGD In Extra-heavy Oil Reservoir

SAGD is one of the effective technologies in developing heavy/extra-heavy oilreservoir. Taking advantage of fast, effective, high oil recovery, etc., SAGD is widelyapplied all over the world. At present, SAGD pilot is successfully applied in FZ oilfield in XinJiang, China. However, the main challenge that is faced to researchers isthe effect of shale barriers on SAGD performance. In order to solve this problem,evaluation of shale barrier’s property is researched in this paper, including basicproperties, thermal properties as well as mechanical properties. The results show thatcompared with reservoir sandstone, thermal and mechanical properties of shale barrierare poorer, which increase the possibility of shale barrier’s failure and deformation onthe same condition.To solve the problem of the effect of shale barrier on SAGD performance,2DSAGD with shale barrier experiment is launched according law of similarity designbased on research of the former researchers. The SAGD gravity drainage theoryforecasting model proposed by Butler is certificated through the experiment. Overall,the SAGD production regular pattern is basically consistent with the theoryforecasting model. The experimental results show that the effect of the shale barrierabove injector&producer on steam chamber is limited, and the shale barrier in oneside of injector&producer affects horizontal development and declining of the steamchamber. Shale barrier’s breakthrough methods are mainly divided into detouring andcrossing. Compared with no shale barrier SAGD, SAGD performance with shalebarrier is poorer, with a little lower and delayed production peak value and lower oilproduction rate and oil steam ratio. Overall, the effects are limited. The improvementof injection pressure contributes to the breakthrough of steam chamber to the shalebarrier as well as the improvement of SAGD performance.Based on the former researches, shale barrier’s breakthrough methods aresummarized in the way of both analyses from oil fields data and numerical simulationstudies. Meanwhile, some front technologies of shale barrier’s breakthrough methodsare introduced in this paper. The findings provide effective technical support for shalebarrier’s breakthrough during SAGD process in the oil field.