Antileaking and Lost Circulation Control Technology for the Mishrif Carbonate Reservoir in the Halfaya Oilfield of Iraq

In order to solve the problem of mud loss in the drilling operations of fractured-vuggy Mishrif carbonate reservoirs in the Halfaya Oilfield, we analyzed such elements as fracture type, leakage factors, and degree of leakage according to the geological and formation conditions of the Halfaya Oilfield. The target area was classified and then zoned in terms of leakage type based on leakage rate statistics and field investigation. In addition, plugging materials and formulas were optimized for different leakage zones, forming the prevention and control technology of the leakage and partial leakage areas as well as the comprehensive treatment technology for the massive leakage area and the complete leakage area. This technology was applied in 21 directional wells in Mishrif carbonate reservoirs since 2019 and resulted in a satisfying application effect. Compared with 2016-2018, the mud loss per well has dropped from 472 m³ to 29 m³ ; complex well drilling dealing time rate has been cut by 12.5%; and drilling cycle has been reduced by 8.5%. This technology provides guidance in the form of a reference for solving the problem of mud loss in the drilling of fractured-vuggy carbonate reservoirs in other similar blocks.