Abstract: Iraq Ahdeb Oilfield is medium-high porosity and low permeability carbonate reservoir. The average of skin factor tested up to 6.21 shows that it is heavily polluted. Iraq Ahdeb Oilfield is quite different from domestic limestone reservoir due to the lithology, physical properties, pore structure and mineral sensitivity characteristics, so the damage mechanisms are not the same. For this, the reservoir sensitivity was experimentally evaluated. The experimental results showed that the main damage mechanism is water sensitivity damage, salt sensitivity damage, stress sensitivity damage, water blocking and solid damage resulting from lost circulation. Reservoir protection measures are put forward, such as strengthening the sealing of drilling fluid for wellbore, minimizing the fluid loss and selecting acid-soluble or oil-soluble loss circulation material, which have achieved good sealing and reservoir protection effect.