Influences of the interlayers in heterogeneous reservoirs on SAGD development and the technical countermeasures

In the SAGD development area of Fengcheng Oilfield, interlayers are widely developed, which has serious influences on production results, so it is in urgent need to prepare the technical countermeasures to alleviate the influences of interlayers on the development. In this paper, the interlayer distribution model was summarized deeply based on fine interlayer characterization, combined with the relationship between interlayer and horizontal well. Then, the influences of interlayers on the injection and production performance of SAGD and the development of steam chamber were analyzed by means of production performance analysis and numerical simulation sensitivity analysis. Finally, the barrier boundary of interlayer was established according to interlayer permeability, differential and interlayer radius, and the technical countermeasures for interlayers were put forward. It is indicated that the influences of interlayers on the development of steam chamber are classified into three types. Type I is the interlayer that steam cannot break through; type II is the one that significantly hinders the development of steam chamber; and type III is the one that has an effect on the development of steam chamber and can be broken through in the later stage. Considering the influences of interlayers, it is proposed to optimize well patterns and well types and introduce new EOR mechanisms and oil drainage enhancing countermeasures. In this way, the proposed three EOR technologies of vertical well assisted SAGD, double-layer tridimensional well pattern SAGD and fish-bone steam injector SAGD are remarkable in field application results, effectively conquer and alleviate the influences of interlayers and improve the recovery factor of SAGD further.