The migration process removes the effect of wave propagation from the recorded seismic data. As an application of this operator, seismic events will move towards their correct positions, diffractions have to collapse and dipping events have to move to their correct subsurface locations. In this article different algorithms of the migration operator have been considered and applied on real data. Based on the results, the Kirchhoff migration, which is the most common algorithm, was chosen and used to apply for pre-stack depth migration on real data. The data obtained from an oil field in the southern part of Iran. Subsequently the obtained results were compared.

The time for easy oil discovery and production for National Iranian Oil Company (NIOC) is over. This means that the oil is no longer discovered in structurally simple, i. e., almost flat environments like south of Khuzestan province (south west of Iran). This comes along with the fact that Iran’ s biggest oil reservoirs are in this area, and they are passing half of their life cycle. These giant reservoirs are still producing more than half of oil production in Iran. There is significant uncertainty in future of Iran oil and gas exploration. In fact, the rate of drilling a successful well by NIOC exploration directorate is dramatically reduced in past few decades. The reason is that nowadays NIOC is drilling in structurally complex areas such as Zagros thrust belt mountains with rough topography and complex geology. Uncertainty in the drilling arises mainly from many factors, one of which is the processing tools in NIOC repository that belongs to at least 30 years ago. These tools belong to the time when NIOC used to drill for easy oil. In addition to the processing, other parts such as exploration techniques need to be revised in structurally complex environments. This article briefly looks at processing tools, which are critical to be used by NIOC to be able to significantly improve the drilling success rate.

Though in most of the countries such as Iran the emphasis has been on rural-urban emigration, the result of censuses show emergence of new current of internal migration with the form of reverse migration or counter-urbanization in recent years in Iran. For recognition and best analysis of reverse migration, 12100 reverse migrants in demographic and economic characteristics, determinants and reason of migration with 23700 metropolis migrants as a result of two percent sample of 1390 census have been studies comparatively. Findings show that in demographic-economic characteristics, age-sex combination, marriage state and head of household, education, and the kind of employment, there is significant difference between reverse and metropolis migrants, the most affective of these differences is migrants’ employment. The superiority of skillful migrants in agriculture and ordinary labor in reverse migration and other professions in metropolis migration has caused migrants’ jobs explain two of three of occurrence changes in under-analyzed migrations. Natural and bio-environmental features of rural and deep structure, economic, commercial, political of metropolis have caused the reverse migrants who entered rural of diverse states and migrants who entered metropolis (Tehran, Mashhad, Isfahan, Karaj, Tabriz, Shiraz, Ahvaz and Ghom) have diverse social, economic features and reasons for this migration

Background and Aim: Migration has been a historical phenomenon that reflects and affects social changes in societies. In recent decades, the growing scale and complexity of international migration have raised concerns among policymakers and planners in developing (or migrant-sending) countries, who face the challenges of human capital loss and development delay in their own countries. This study examines the question of whether these migrations can be seen as a facilitator of development course or as a reducer of human capital in the long run for the countries of origin?   Methods and Data: The present study is a narrative review that analyzes relevant literature from 2000 to 2022 using a descriptive-analytical approach.   Findings: Results show that international migration follows have individual and collective benefits for migrants, their families, and their origin countries. Depending on how the capacities of the migrants are utilized, these migrations may also have negative impacts or challenges for development. In other word, as litrature suggests, international migration does not necessarily reduce human capital, but depending on the way of using its capacities, it can facilitate development for the origin countries.   Conclusion: The phenomenon of international migration, which reflects the freedom of choice and the common right of individuals and communities to benefit from this option in their lives, requires careful attention from policymakers and planners. Governments should adopt policies that increase the benefits and reduce the risks of migration for their communities.   Key Message: Governments of migration-sending countries should change their attitude towards international migration from a merely threat to a possible opportunity in their population planning and take necessary steps to benefit from the potentials of these immigrants in the direction of their own country's development.

A medium is isotropic if its elastic properties do not change with direction. The usual meaning of seismic anisotropy is variation of seismic velocity, which itself depends on the elastic properties of the medium, with the direction in which it is measured. In sedimentary rock sequences, the anisotropy may be caused by preferred orientation of anisotropic mineral grains, preferred orientation of cracks or thin bedding of layers. Anisotropy parameters that defined by Thomsen are ε and δ. Thomsen’s anisotropic parameters are estimated by well and seismic data. However, one difficulty in addressing anisotropy lies not in the algorithms, but in the reliable estimation of anisotropic parameters. Most of seismic data analysis assume isotropic behavior for subsurface while the earth is often anisotropic and seismic velocity isn’t constant in different directions. So, this analysis must consider anisotropic assumption. One of the most common anisotropy-related phenomena is seismic imaging. Output of migration is the section that is similar to the geological model. Depth migration leads to correct image when velocity changes laterally and vertically in the subsurface. Generally, isotropic Pre-Stack Depth Migration (PSDM) corrects only for lateral velocity heterogeneity; however, anisotropic PSDM algorithms also correct for velocity changing with direction. Anisotropic PSDM corrects for vertical shifts, correctly positions events in depth, and properly focuses diffraction energy.  Thomsen’s anisotropic parameters, ε and δ, are two main parameters required in a velocity model for PSDM imaging. Accurate estimation of travel time is very essential in seismic imaging and velocity analysis. Inaccurate approximation of travel time leads to migration errors.  Several equations have been developed for nonhyperbolic travel time approximation in transversely isotropic media with vertical symmetry axis (vertical transverse isotropy, VTI). In this study, 2D seismic line and well data are used for doing isotropic and anisotropic PSDM. Conventional processing sequences are performed on seismic data. Initial velocity model was created and then 3 horizons were picked on seismic section. Anisotropy parameters are calculated using true depth of horizons in seismic and well data and then PSDM is performed with and without considering anisotropic parameters. Results of applying anisotropic PSDM in seismic data show that this method moves the events to correct positions and can significantly reduce seismic-to-well mis ties, hence, providing more accurate structural images in depth domain.  In addition, anisotropic PSDM attenuates the hockey stick events on CDP gathers and so improves reflector continuity in the subsurface image especially in shallow parts.