Enabling Shallow Reservoir Development in Malaysian Deepwater Field Via Statically Underbalanced Mud with MPD Applications

Abstract

Managed pressure drilling (MPD) technology is a widely accepted technology for wells with narrow pore- pressure/fracture-pressure (PP/FP) gradient window. Whilst MPD is often associated with high capital expenditures (CAPEX) that further erodes the project economics especially for marginal reserves, it does not limit its application since MPD technology can considerably reduce non-productive time (NPT). Most importantly, it is the key enabler to access the previously conventionally un-drillable reservoir target, generating significant revenues to the organization. As the plan new development well cannot be drilled conventionally by using overbalance mud, numerous dynamic drilling simulations were performed utilizing drilling engineering software to ascertain its drill- ability via constant bottomhole pressure (CBHP) MPD with statically underbalanced mud. As an input, detailed surface equipment specifications, i.e., surface MPD line up and well control equipment are important to ensure successful drilling simulations. Sensitivity analysis using surface back pressure and drilling mud density are performed to determine maximum drillable footage for each hole section. As proper cementing is paramount for well barrier, well drill-ability is further assessed with managed pressure cementing (MPC) simulation to ensure the well is operationally executable. This paper presents a case history on operations performed in-house well engineering design for a complex and marginal deepwater development field during front end stage with narrow PP/FP gradient window (less than 1ppg drillable mud window) and elaborate on extensive work done for MPD engineering planning procedures in designing a fit-for-purpose well design.