In wrench faulted areas, similar to the one introduced here identifyingstructural styles and their histories could be one of the most important tasksin studying tectonic related fractures and faults. The main purpose of thispaper is to examine the patterns and structural positions of producti vefractures in different reservoir structures of the Asmari formation(oligo-miocene) in Khuzistan oil fields belt of south west Iran.
Details of productive fracture positions have been studied on four major Asmari reservoirs, using production data(e.g., production rates andproductivity indices) which are the most reliable indirect fractureidentifiers, mud losses to identify open fracture portion, faulted wellsassemblages to find tectonical active portions and second derivative maps tofind the portions of the maximum rate-of-change-of-dip on top of the reservoirstructures, where it is expected to have maximum fracture density. Theresults were then compared with the surface fracture patterns and densities inthe K Asmari of the mountain front boundary in the area. Productivefractures were found to be mostly associated with the plunges and bends of the Asmari reservoir structures.
Identifying structural styles and their histories could be one of the mostimportant tasks in studying tectonic related fractures. These styles aregenerally differentiated on the basis of the extent of the tectonic basementinvolvement and or the detachment of sedimentary cover. In Khuzistan oil fieldsbelt south west Iran, reservoir structures have become further complicated bysuperposition of fundamentally different tectonic regimes which based on high concentration of earthquake foci in the area, are still continuing.
