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    • List of Articles Fracture

      • 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 - Numerical calculation of permeability tensor in fractured reservoirs
        سیما جلیلی رئوف حسین معماریان محمد رضا  رسائی بهزاد تخم چی
        Abstract Proper characterization of fracture reservoir is crucial for their sound development plan. It is however very difficult to correctly obtain various fracture reservoir properties such as permeability due to high order of heterogeneity and anisotropy within th More
        Abstract Proper characterization of fracture reservoir is crucial for their sound development plan. It is however very difficult to correctly obtain various fracture reservoir properties such as permeability due to high order of heterogeneity and anisotropy within these reservoirs. Classical dual porosity and/or dual permeability models consider a regular fracture network across the reservoir. To improve the concept, we develop a numerical method for tonsorial permeability calculation of blocks with random/disordered fracture distribution. We considered a 2D Cartesian fine grid in which the fractures were defined explicitly with their endpoints coordinates. Applying proper boundary conditions, single phase flow is then solved. Full tensor permeability is then obtained analytically from the calculated flow and pressure fields. The result of our method is compared well with that of the analytical models for simple fracture systems. In addition we reported the permeability tensor values of random fracture networks where no analytical solution is available. Manuscript profile
      • Open Access Article

        3 - Fractures systematic analysis Asmari reservoir Formation in the Marun oil field (based on image logs interpretation results)
        فارسی مدان arsimadan
        In the oil buildings to investigate fractures in the reservoir rock fractures in stages of production and field development is very important and necessary. Now application of software repository in the realization of this issue will help to petroleum with the geologist More
        In the oil buildings to investigate fractures in the reservoir rock fractures in stages of production and field development is very important and necessary. Now application of software repository in the realization of this issue will help to petroleum with the geologists.. Marun oil field is one of the largest oil fields in the South West Iran of the city of Ahvaz in the Northeast and the North embayment Dezful of geology in the eastern. Marun field is the most important Asmari reservoir. The aim of this study was to investigate systematically Asmari reservoir fractures and the development of fractures in the reservoir. For this purpose, using image logs, best and most complete method interpretation and results of 11 wells in fracture studying and 16 wells in in-situ stress direction studying. According to frequency of fractures (based on image logs interpretation results) in the southern and north-eastern limb of the field, The theory of tectonic folding and bending events later caused the possible activities during the north-south strike-slip faults affect the compression force has been created to strengthen. Most of image logs data in Marun field are fractures with extensions; N155E, N130E, N95E, N60E, N30E. Manuscript profile
      • Open Access Article

        4 - 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
      • Open Access Article

        5 - Structural Modeling and Estimation of Tectonic Stresses at Lali Oilfield in Dezful Embayment
        Nasrin kianizadeh Behzad Zamani Rahym khadkhodayi Hoseyn Talebi
        Structural geological study is one of the most important stages of an oilfield exploration and production (E&P) program, since a knowledge of existing structures can play a fundamental role in the oilfield development plan. The main purpose of this study is to create More
        Structural geological study is one of the most important stages of an oilfield exploration and production (E&P) program, since a knowledge of existing structures can play a fundamental role in the oilfield development plan. The main purpose of this study is to create three-dimensional (3D) structural models to determine direction of tectonic stresses at Lali oilfield using subsurface geophysical data. The study area is located within the so-called Dezful Embayment (northern Khuzestan Province, Iran). Accordingly, in order to provide a 3D model of the reservoir, geostatistical tools in Petrel Software were utilized. Incorporating density log data into several coded formulations in MS Excel Software, the reservoir had its modulus of elasticity calculated. Subsequently, maximum and minimum horizontal stresses were calculated using poroelastic equations. Fault modeling results showed that, fault dip increases with increasing the depth towards the center of the field. Obtained values of stress using the poroelastic equations show that σ_H>σ_h>σ_v, confirming a regional reverse stress regime, which is consistent with previous studies in this area. Also, the formal stress ratios (Φ = (σ2-σ3) / (σ1-σ3)) obtained from poroelastic equations and inverse analysis method were found to be well-correlated across the area. Finally, average azimuth of the reverse faults on the southern limb (as calculated by Petrel) and the fractures on the limb (as obtained from FMI images and core samples) were found to be N305 and N315, respectively (average = N310). Thus, N040E was inferred to be the average direction of principal stress, i.e. principal stress is mostly directed along a NE-SW axis (perpendicular to the general trend of Zagros Orogeny); this is probably a result of the activities of youngest Zagros orogeny phase. The agreement between the obtained principal stress directions by fractures, faults, and focal mechanism of earthquakes across the World Stress Map (WSM) confirms the validity of this study. Manuscript profile