Reservoir Heterogeneities between structural positions in the anticline: A case study from Kela-2 gas field in the Kuqa Depression, Tarim Basin, NW China

There are strong heterogeneous characteristics of reservoir property between the core and limbs of the Kela-2 anticline, although they are in the same structure. The reservoir heterogeneity mode of “small-scale and east-west” cannot be explained by the distribution mode of compressional stress “large-scale and south-north” proposed by previous scholars. Statistical result of petrographic composition and diagenetic characteristics shows that the differentiation of reservoir compaction between the core and limbs of the Kela-2 anticline is clear. The differentiation is controlled by the difference of tensile stress suffered by strata above the neutral plane during folding deformation. The tensile stress suffered by strata in the anticlinal core is stronger than that in the anticlinal limbs. In the Kela-2 anticline, the difference of tensile stress between the anticlinal core (Kela-201) and limbs (Kela-203 & Kela-204) is obvious. The tensile stress offsets the compaction effect caused by vertical and lateral (south-north) stress, and it is constructive to reservoir quality. It is the major factor controlling the differentiation of reservoir compaction.