| The fractured-vuggy carbonate condensate gas reservoir of the Yingshan Formation in TZ83 well area is an important part of the huge Ordovician carbonate condensate gas reservoirs in Tazhong Ⅰ gas field, Tarim Basin. On the basis of well-seismic calibration and fine interpretation of seismic data, seismic attributes such as curvature, coherence and wave impedance were used for identifying and studying the cyclic fault-karst reservoir in TZ83 well area, and the development characteristics and oil-gas accumulation rules of cyclic fault-karst reservoir have been concluded as following: (1)The cyclic fault-karst reservoir is a ring cave layer which is mainly developed in the Yingshan Member 1 to Lianglitage Member 5. (2) The widely developed unconformity karst in the Middle Caledonian forms the rudiment of cyclic fault-karst, and the X-shear fault formed in the Late Caledonian to the Hercynian controls the scale of the cyclic fault-karst. (3)The distribution of oil and gas is mainly controlled by the scale of the cyclic fault-karst reservoirs, which can be divided into three relatively independent oil and gas reservoirs with great differences in hydrogen sulfide content, gas-oil ratio and development characteristics. It is pointed out that the cyclic fault-karst reservoir in TZ83 well area is formed under the influence of X-shear fracture in the condition of weak strike-slip, and the cyclic fault-karst reservoir has such characteristics as “selectivity, controllability, inheritance and heterogeneity”, which is quite different from the fault-karst controlled by large regional strike-slip fault in other areas of Tarim Basin in reservoir forming mechanism and oil-gas distribution. |
