Pre-drill surface seismic in the vicinity of the AIG-10 well and post-drill VSP

Pre-drill reflection surface seismic was carried out in the Aigion city area in February 2001. The poor quality of seismic reflections obtained from standard processing did not allow us to refine the location of the vertical well AIG-10 to be drilled. Subsequently, a brief study of refracted seismic arrivals was attempted in order to better define the well location, in conjunction with observations from a shallow well. In 2002, after drilling, an innovative 6-VSP position well seismic survey was successfully run, using a four-component downhole sensor tool, i.e., three orthogonal geophones and a hydrophone. Refracted seismic events and first arrivals from VSP indicated the throw of the Aigion Fault and the fault plane dip; a secondary accident striking about southunorth was detected about 100 m west of the well. No PuP seismic reflection was evidenced from standard VSP processing.Original Abstract: Une campagne de sismique reflexion de surface fut tiree dans la zone daAigion en fevrier 2001: les resultats du traitement standard reflexion, trop pauvres, naont pas permis daaffiner le modele structural pour implanter le puits vertical AIG-10. Une breve etude des arrivees refractees fut alors tentee, afin de mieux definir la position du forage, combinee a des observations daun puits a faible profondeur. A laautomne 2002, apres forage, une campagne de sismique de puits innovante, comprenant six VSP, fut conduite en utilisant un outil de puits a quatre composantes de reception : trois geophones orthogonaux et un hydrophone. Les arrivees directes et diffractees des VSP ont permis de preciser le rejet vertical de la faille daAigion et le pendage du plan de faille, tandis quaun accident secondaire sensiblement nordusud a 100 m a laouest du puits a ete revele. Aucune reflexion PuP naa ete mise en evidence par le traitement VSP.