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۱Using Vp\Vs Ratio to Predict Fluid Type in oil reservoirs a case study from an oil field, southwest of iran
نویسنده(ها): ، ،
اطلاعات انتشار: چهاردهمین همایش بین المللی نفت، گاز و پتروشیمی، سال
تعداد صفحات: ۸
the compressional wave velocity is a key foe lithology and porosity prediction in petrophysical analysis sonic logs. Shear wave velocity is very useful in determing mechanical rock properties . In oil and gas reservoirs compressional wave velocity decreases and shear wave velicity increases. the increase of shear wave velocity is due to the decrease of density and the absorption of deformation by oil in pores and the decrease of compressional wave velocity is due to the decrease of bulk modulus of reservoir rocks; therefore the Vp to Vs ratio, Vp\Vs, will decrease and it is more sensitive to change of fluid type than Vp or Vs separately. the use of Vp\Vs is a key parameter in reservoir study and it plays a key role especially for lithology and fluid type prediction methods. a field example in southwest of iran is given to identify fluids type water and oil using the Vp\Vs ration form well logs . the results have shown that shear wave velosity increases and compressional wave velocity decreases when the water saturated points become oil saturated points in the studied intervals.<\div>

۲Carbonate cements investigation in Permo–Triassic Dalan–Kangan reservoirs: Case study in Persian Gulf, Iran
اطلاعات انتشار: اولین کنفرانس و نمایشگاه تخصصی نفت، سال
تعداد صفحات: ۷
This study is conducted to investigate carbonate cement in the Permo–Triassic Dalan–Kangan reservoirs in the Persian Gulf. Samples were analyzed through conventional, cathodoluminescence, and fluid inclusionmicroscopic techniques. The studied thin sections are cemented by calcite, and dolomite precipitated frommarine, meteoric and burial waters that circulated through the sediments during the early and burial diagenesis. The sequence has gone through five stages of calcite and dolomite cementation that completely or partially occluded pores. Each stage represents a distinctive cement texture, precipitating at specific temperatures,salinity and burial conditions. Precipitation occurred from very early to late diagenesis stages.Cement typesappear to be early (1) granular isopachous calcite, with red CL, burial and meteoric (2 , 3) equant calcite withdull red and bright orange CL, burial (4) coarse sparry calcite with dull CL, and (5) fairly coarse secondary dolomite (100<size micron) rhombs with zoning red CL,. With progressive burial and increaseingtemperature, fluids are responsible for the cement precipitation in Kangan and Dalan Formations can besubdivided into three groups. Group 1 is fluid with calcite composition, has Th values (126 C), and salinity (16 wt.% NaCl equivalent) and is interpreted to have precipitated during shallow burial from porewaterinfluenced by meteoric water. Group 2 fluid with dolomite composition has Th values (127 C) and salinity (17wt.% NaCl equivalent), demonstrated that the coarse dolomite crystals was precipitated possibly duringshallow burial. Group 3 occurring along fractures is characterized by high Th values (169°C) and salinity (17.5 wt.% NaCl equivalent). It means the fluids with higher temperature, migrated from deeper parts of thebasin and filled fractures during deep burial. The oil inclusions with yellow fluorescent can be observed in 3 samples in fracture filling calcite from Dalan Formation. It can be interpreted that oil inclusions are secondary and oil migration posdate the precipitation of fracture filling cements.<\div>

۳Investigation of Porosity Effect to Determine Uncertainty in Archie's Water Saturation Equation Parameters, Case Study: Two Reservoir Formations from an Iranian Oil Field
اطلاعات انتشار: اولین کنفرانس و نمایشگاه تخصصی نفت، سال
تعداد صفحات: ۸
Formation A and Formation B are main reservoir intervals in one of the Iranian oil fields which were considered for uncertainty study. Uncertainty in calculated water saturation has a direct economic impact on both exploration and development projects, yet is rarely quantified by petrophysicists.Cementation factor (cementation exponent) is one of the most important parameters in saturation equation to determine the water or hydrocarbon saturations. It acts as a power of porosity in the most of saturation equations which increases the importance of this parameter.Monte–Carlo Simulation and @Risk software was used for uncertainty analysis. Four different scenarios were assumed and different models were run for each zone. The results show that cementation factor is highly important in saturation calculations and small variation in cementation factor values can affect the results of water saturation determination considerably. Also in high porosity zone Shell formula is a suitable equation for calculation of cementation factor (m), but in low–porosity zone using a constant value for cementation factor is better than using Shell formula.<\div>
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