Effects Deliberation of Fractures and Determination of in-situ Stress in Asmari Reservoir Formation in Marun Oilfield (Based on Image Logs Interpretation Results)

Zagros Fold-Trust belt with 2000 km length and it’s hydrocarbon reservoirs is the richest fold-trust belt in the world. Marun Oilfield is one of the biggest reservoir in south-west of Iran and north-east of Ahwaz city also in north Dezful embayment. Asmari Formation is the most important reservoir in Marun oilfield. Nowadays, knowledge about state, magnitude and in-situ stress direction in different studies of Oil and gas reservoir like geology, drilling and petroleum engineering is cleared. Study of in-situ stress in hydrocarbon reservoirs is divided to some part like state of stress, magnitude and the direction of stress tensors from each other. One of the advantages of stress study in hydrocarbon reservoir is usage these results in reservoir geomechanics that could solves some problems like wellbore instability during drilling, choosing safe trajectory, casing failure, different methods of reservoir stimulation, have an important role. This research was paid to review and determination of in-situ stress direction in Asmari reservoir formation in Marun Oilfield. For Analysis of in-situ stress direction, the result of image logs is the best way to use and so 19 wells became candidate. Also on this research, because of the importance on most of reservoir geomechanics applications, minimum horizontal stress direction was in focus. Finally, because of structural complexity and stress concentration in the ends of Marun structure, it determined that in-situ stress direction was changed but in other places has the strike of NW-SE. If both the north and north-east and centre fractures are associated with folding and bending seen, based on maps along fracture zones located on the southern limb of the layer at wells No. 181, 341, 322 and 278 in the eastern cape of along the dominant fracture orientation E130N, except those marked the longitudinal tensile fractures.