Analysis of Fractured Reservoir Structure by Interpretation of FMI and VSP Logs

Abstract

Imaging technology into the well is the tools for logging system, interpretation of data obtained from the well and to create the image with high resolution from the wells. This technology creates an accurate image (screenshot tools and the vertical seismic) on structural characteristics, layering, fractures, faults, texture and secondary porosity play an important desirable role in describing the reservoir. In the carbonate reservoirsthat most of Iran reservoirs are included in this type fractures are the most important factor in the production of these reservoirs. In the fractured carbonated reservoirs faults and folds makes unwanted changes in the structure of these reservoir. Structural complexities occur at different scales. For example, major faults and the original boundaries between formations are visible on the surface seismic data. But small-scale changes and faults in seismic data cannot be determined and it is essential to use small-scale of data and information sources. For achieving to these purposes it can be combined the result of small-scale data such as internal wellbore seismic VSP (vertical seismic profile) that having separating power in meter limit and FMI (formation micro imager) imaging logs that having separating limit in centimeter limit that could be able to modeling structural complexities and distribution of fractures around well. It should be noted that identifying occurrences around the wellbore is very important in drilling, completion procedures and development programs. FMI (formation micro imager) logs can be directly determined the inverted changes of wellbore layers and formation structures and also was an important factor for stratifying layers and determining the lithology of oil and gas explorations that can be determined the wellbore fractures, inclination and direction by using its interpretation. Moreover VSP (vertical seismic profile) logs is the way that generated signals at the surface are received by the geophone at different depth levels in the wells, which by its interpretation; changes in wellbore direction, velocity profiles, faults with higher accuracy around the wells and fractures around the well can be determined.