Pre-Planning of Casing Seat Position to Choose Optimum Equivalent Circulation Density to prevent lost circulation

Loss of drilling fluid in the Nasiriyah oil field can be considered as a big, serious, and expensive problem at the same time, therefore accurate and integrated program must be prepared before start drilling in layers that are likely to get loss circulation. From the available data of well Ns-13, the area of loss was detected in five layers, which are Dammam, Um- radoma, Tayarat, Shiranish and Hartha since these layers contain natural cracks and high porosity represented by vugs. Methods of prevention have been identified by specifying the minimum values of drilling parameters to reduce hydrostatic pressure, thus reducing equivalent density of drilling mud during the circulation, depths of casing shoes is determined (2500 ft, 3550ft, 5300ft and 6894.5ft) to strengthen the wall of the well and prevent losses.