Reservoir property difference 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 difference in reservoir property between the core and limbs of the Kela-2 anticline although they are in the same structure. The heterogeneity of “small-scale and east-west” in the Kuqa Depression cannot be explained by the distribution mode of compressional stress “large-scale and south-north” proposed by previous scholars. Statistics of rock constituents and characteristics shows that the differentiation of reservoir compaction between the anticlinal core and limbs of the Kela-2 anticline is clear, which is controlled by the difference of tensile stress suffered by strata over the neutral plane during fold modification. 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) stresses, and it is constructive to reservoir properties. It is the major factor controlling the differentiation of reservoir compaction.