Publications

Drilling through Carbonate formation with high amount of vugular pores and fractures can be a difficult and high risk operation when using conventional drilling methods. Total lost circulation problems with series of influx following will be encountered when high volume of pore and great amount of fractures are drilled through. Using Managed Pressure Drilling (MPD) techniques when drilling through severely vuggy and fractured formation can reduce drilling hazard of total lost circulation problems and prevent influx to reach the surface while drilling is in progress. The application of the Pressurized Mud Cap Drilling (PMCD), a variant of MPD, in recent projects in Indonesia has been successful in allowing drilling operation to reach targeted depth. Pressurized Mud Cap Drilling (PMCD) is a non-conventional drilling technique designed to control wells which encounter total loss circulation problems. Sacrificial fluid is pumped through the drillstring to circulate drilled cuttings to vugular pore and fractures. Viscous fluid that has a slightly less density than formation equivalent mud weight is filled in the annulus to prevent influx from reaching the surface. With the utilization of MPD equipment especially the Rotating Control Device (RCD), mitigating drilling hazards of total loss circulation and any gas migration in the project can be conducted without stopping the drilling process. Proper bullheading sequence is performed in order to control influx which is migrating through the mud-cap to the surface. With applications and actual operations on location, which will be discussed in detail in this paper, drilling operations have successfully reached targeted depth with minimum NPT and optimum hazard and cost reduction.