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      • Open Access Article

        1 - Wellbore Stability Analysis During Drilling Using Geomechanical Model and FLAC3D Software in Asmari Reservoir, Ahwaz Oil Field
        Mohammad میرانی
        Abstract Oil reservoirs are one of the important sources of energy due to which is caused by specific rock mechanical properties, the ability to maintain hydrocarbon fluids. One of the major problems that are occurred during drilling a well is instability of the well More
        Abstract Oil reservoirs are one of the important sources of energy due to which is caused by specific rock mechanical properties, the ability to maintain hydrocarbon fluids. One of the major problems that are occurred during drilling a well is instability of the wellbore. In order to prevent this difficulty its need to predict stability of the rocks by using geomechanical properties and in-situ stresses. A lack of accurate wellbore stability analysis brings many problems such as borehole washout, breakout, collapse, stuck pipes and drill bits. In the present research work the stability of an oil well located in Asmari reservoir of Ahwaz oil field was stimulated by using numerical software FLAC3D and information obtained from well log curves were evaluated and analyzed in two parts and the results were presented. Mud pressure and mud weight in outset of wellbore plastic flow and also outset of shear failure in wellbore were obtained for 7.5 meter of formation which mainly consists of limestone, marl. Well stability analysis was performed in vertical direction, minimum horizontal stress and maximum horizontal stress. Due to plastic movement and shear failure in wellbore, in first stage the mud pressure occurred is 33 and 26.4 Mpa and the second stage it reaches to 45 and 30 Mpa, respectively.It indicates that tensile failure is in direction of maximum horizontal stress and shear failure in direction of minimum horizontal stress. Subsequently, the result shows that the analysis due to the low mechanical properties of the sandstone layer indicates the maximum amount of displacement and loss. The safe mud window is small in this layer. Manuscript profile
      • Open Access Article

        2 - Fracture analysis of the Asmari Formation of Dara anticline, as analog model for other Asmari subsurface hydrocarbon reservoirs
        saeed mohammadi asl Ali Farzipour Saein Ghodratollah Shafiei
        The quality of the Asmari Formation, as the reservoir rock of almost three-quarters of the explored oil In Southwest Iran, is often affected by the fractures system. In this paper, in order to study fracture patterns in the Asmari Formation, as well as to present an ana More
        The quality of the Asmari Formation, as the reservoir rock of almost three-quarters of the explored oil In Southwest Iran, is often affected by the fractures system. In this paper, in order to study fracture patterns in the Asmari Formation, as well as to present an analog model for other Asmari reservoirs, the Dara anticline in South Dezful depression, which has extensive outcrops of the Asmari Formation, has been studied. During field studies, eleven stations on the anticline, in its different structural positions, have been investigated. In the southwestern limb, four fracture sets trending AZ40-50,AZ130-140,AZ10-20,AZ80-90, in the northeastern limb four fracture sets trending AZ130-140,AZ50-60,AZ170-180,AZ110-120, and in its hinge area, three fracture sets with AZ50-60,AZ130-140,AZ0-10 trends have been identified. From the structural perspective, all the identified fracture sets are associated with folding. In this study, the relative formation time of the identified fractures relative to folding, has been diagnosed as before or simultaneously with folding. Based on field studies, fractures density in the Dara anticline, the Asmari outcrop, ranges from 11.75 to 2 fractures per meter. Indeed, variation range of the fracture length is 1 to 25 m and most fractures have a length of lower than 5 meters. Also, in this study it was found that there is a negative logarithmic relationship between fracture density and sedimentary layers thickness. Manuscript profile