New advances in drilling operations in sandstone, shale, and carbonate formations: a case study of five giant fields in the Mesopotamia Basin, Iraq

Drilling challenges in the Mesopotamian Basin, Southern Iraq, are varied and include such issues as mud loss, bit damage, and differential sticking. This study aims to analyze these problems across the stratigraphic column in the study area. The results show that the MMD65R, EQH16R, and SF74R bits were successfully used for the 16” section, while the MSi616L bit was the most efficient for the 12¼” section. The MMD65R was suitable for the 8½” section, with the EQH12DR bit being used for the remaining parts of this section. The MMD54 bit showed excellent performance, achieving the highest rate of penetration (ROP) of 26.9 m/hr in well horizontal sections. Mud losses were most commonly observed at the base of the Dammam, Rus, Tanuma, Mishrif, Hartha, Shuaiba, and Zubair Formations. An appropriate drilling mud density is 1.28 sg is recommended for Zubair and Mishrif Formations. Additionally, tripping in/out operations must be conducted at controlled speed to prevent surging or swabbing the well. Potassium Chloride concentrations should be maintained between 3 to 5%. A 7” production liner must be run and properly seated to isolate the Mishrif and Zubair Formations, with overlap to prevent potential communication between lower water-bearing zones and shallow loss zones.