f Mechanical Formation Damage Due To Stress Concentration Induced By Drilling In Sarajeh Gas Field, Iran

Formation Damage is a kind of damage occurs in reservoir rock, in the vicinity of oil and<br>gas wells. Such damage could leads to notable reduction of permeability and porosity. Among many<br>activities which can be the source of formation damage, drilling is the major one. Drilling mud can<br>cause serious problems by infiltrating into the porous media. Another type of induced damage is<br>mechanical, which is mostly due to redistribution of stress and its concentration near the well wall.<br>This in turn reduces the productivity index of the well. Stress concentration, induced by drilling, can<br>be calculated by various methods, such as Kirsch or Salencon theory. Numerical models, which<br>accept wide range of parameters and are adaptable to well situations are among the best suggested<br>methods.