Influence of Heterogeneous Reservoirs with Different Depths on Casing Deformation in Fuling Area

Abstract

In shale gas horizontal well fracturing operations, casing deformation and cement ring damage occur mostly in heterogeneous formations. Based on the characteristics of shale gas reservoirs in China and related literatures, this paper establishes a finite element model of heterogeneous stratum for the Fuling shale gas field and studies the effects of heterogeneity on casing deformation at different depths. In the heterogeneous stratigraphic model, the effects of shallow reservoir heterogeneity and deep reservoir heterogeneity on casing deformation were analyzed. The results show that the shallow reservoir heterogeneity and deep reservoir heterogeneity affect the casing deformation in different aspects; the stress that is subjected to casing in the shallow reservoir is greater than casing in the deep reservoir; at the lithological interface, the abrupt of stress change in the deep reservoir is significantly larger than that in the shallow reservoir. This conclusion is also applicable to other shale gas fields in China; In the development of shale gas resources, the shallow reservoirs should focus on the overall strength design of casings, the deep reservoirs should focus on the strength design of casings at lithological interface points.