Updating The 2D Seismic Data by Pre Stack Depth Migration of Khashim Al-Ahmer Gas Field Northeastern Of Iraq

Abstract

Khashim Al-Ahmer Gas Field is located at North-Eastern Iraq, particularly in Diyala governorate. The final seismic data for this gas field is carried out through three main phases: acquisition operations, processing, and interpretations. This research is concerned with the second phase of seismic work, which is the seismic data processing phase, the seismic data processing phase also consists of three stages, and each stage includes a series of interrelated steps which are: noise attenuation stage, final stack stage, and the migration stage. The migration stage is an advanced step of seismic data processing, the purpose behind its application is to provide a more accurate image of the subsurface and close to the geological reality. The seismic migration has several types that are used according to the nature of the geological complexity. The type of seismic migration that was used in this research is the Pre-Stack Depth Migration (PSDM). This type of technique is used if the field to solve subsurface geological complexity, and the seismic velocity behavior is complex as well, this is actually present in the Khashim Al-Ahmer gas field, as it contains layers of evaporites within the L. Fars Formation it is subjected to a process of folding and thrusting. The Jerebi Fn. Which lays below considered as a major gas reservoir. These factors lead to a high attenuation of seismic waves energy and produces high uncertainty in interpreting variations of geophysical parameters, and the best solution was to remove this uncertainty by applying the (PSDM) technique. Where it is possible to recover the seismic signal strength also, to avoid the effect of high geological deformation resulted by folding, thrusting, layers of evaporites and the effect of gas reserve. This makes the interpretation process extremely easy for the interpreters.