Fracture, Dissolution, and Cementation Events in Ordovician Carbonate Reservoirs, Tarim Basin, NW China

Figure 6

(a) Hand specimen of the Tumuxiuke Formation showing F1 fractures. (b) Plane light optical photomicrograph of palisade calcite (Cc1) and internal sediment (Cs1) in an F1 fracture. (c) Plane light optical photomicrograph of F2a fractures crosscutting calcite sediment Cs0a within rounded mottle fabrics. (d) Plane light optical photomicrograph showing a F2b fracture crosscutting a F2a fracture. (e) Optical-CL photomicrograph showing Cc2 calcite infilling F2 fractures and V2 vugs. (f) Hand specimen of the Tumuxiuke Formation showing F3 fractures. F3 fractures cross-cut rounded mottle fabrics. (g) Panchromatic SEM-CL image showing Cc3a calcite crystals that are zoned in SEM-CL. Bitumen fills remaining void space in the center of the fracture. (h, i) Cc2 and Cc3a calcite cements under (h) plane light and (i) optical-CL. (j) Hand sample specimen showing F4a fractures. (k) Plane light optical photomicrograph showing F4b fractures filled with blocky calcite (Cc4). (l) Plane light optical photomicrograph showing F4a fractures filled with blocky calcite (Cc4) and concurrent pyrite.

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