The highly pressurized intervals coupled with high permeability makes the drilling of the 6-1/8” horizontal hole section particularly challenging in the water injector wells, as mud losses are frequently encountered with differential sticking events. The objective of the workover operations in the objective field is to sidetrack the power water injector from the existing well's motherbore, converting the well in to a dual lateral, which will maintain the reservoir pressure and enhance oil recovery from the oil bearing formation. This variance in formation pressure distribution makes drilling with high mud density systems a challenge, and increases the risk of encountering losses and differential sticking.
To overcome the challenges mentioned, the application of MPD technology with the Constant Bottom-Hole Pressure (CBHP) method during the drilling of the 6-1/8” hole section enables utilizing a mud system that is statically below the formation pressure, while keeping the Equivalent Circulating Density (ECD) slightly over the formation pressure and constant at static and dynamic conditions. This objective is achieved by applying surface back pressure using an Automated MPD control choke manifold. As the drilling continued in the lateral, dynamic formation pressure evaluation was performed to assess the changing formation pressure, and to adjust the drilling parameters.
This paper will summarize the results of the MPD campaign, compares conventional drilling methods, and highlights the lessons learned from the application of the MPD (CBHP variant), to enhance drilling efficiency, and to mitigate drilling hazards such as losses and differential sticking. The analysis will further enhance the drilling practices of the Power Water Injector wells.