h Rahmanifard - Drilling Fluids Engineering and Waste Management Department, Deputy Managing Director of NIDC Projects, NIDC, Ahwaz, Iran,
a.r Rasouli - Drilling Fluids Engineering and Waste Management Department, Deputy Managing Director of NIDC Projects, NIDC, Ahwaz, Iran,
n Mayahi - Drilling Fluids Engineering and Waste Management Department, Deputy Managing Director of NIDC Projects, NIDC, Ahwaz, Iran,
a.h Amouri - Drilling Fluids Engineering and Waste Management Department, Deputy Managing Director of NIDC Projects, NIDC, Ahwaz, Iran,

Controlling loss circulation with lost circulation materials (LCM) has achieved wide success in the past years. However, investigation into the strength and stability of plugged zone has gained little interest. In fact, ignorance of such knowledge often leads to excess costs from repeatedlyfluid loss and rig time, and increase the difficulty and complexity of loss zone diagnosis. In this work, drilling and cementing operations of hole 12 ¼ of two wells in Azar Oil Field are investigated. Because of the wide range of the pore pressures of formations that are supposed to be drilled in this hole, successive partial to complete loss circulation would be expected. In order to strengthen the formations, prevent losses, and curing them under the case of their occurrence, a combination of solutions including LCM pills (lamellated ones), mud weight reduction, running an excessive casing, cement plugs, and pumping sodium silicate are deployed which lead to finish the drilling and cementing operations of the hole with acceptable results

Loss circulation, LCM, Sodium silicate, cement plug, Azar Oil Field