Extreme Underbalance Perforation on the Wire

Abstract

Abstract Total E&P Borneo B.V. (TEPB) operates the M field in the Block B, located in the South China Sea at approximately 55 km from the Brunei shoreline in 60 m of water. The field has been producing gas and condensates since 1999. The initial field development plan did not exploit all reservoirs encountered in a well to optimize spending by distributing zonal exploitation to different development wells. Later during the field life, these non-perforated zones are planned to be opened. The remaining non-perforated zones may be still at un-depleted reservoir pressure while the bottom hole pressure at producing development wells is at depleted pressure which can result in an underbalance perforation operation more than 10,000 psi (689.5 bar). However, the allocated intervention budget is limited as there are possibilities that these non-perforated zones will be depleted. In addition, pressure information obtained by partially perforating these zones will be used as a justification to secure higher budgets for coiled tubing or a workover rig to perforate potential unperforated zones fully in adjacent wells apart from possibly mobilizing a drilling rig to add infill wells. These mono-bore wells also have scale deposition issues. Perforation options that leave fish in the well are not desired. A slickline perforation method was selected due to lower cost through efficiency and using smaller diameter high performance guns for lower risk. Extensive preparations and pre-job modeling were required and performed to plan for this slickline conveyed extreme underbalance perforation project. Some of the critical steps includes: Stakeholder communications Production logging before perforation Wellbore steady state/transient flow modeling Tension and gun lift modeling Perforation modeling to plan for a suitable gun Gun shock modeling Operational flow chart Contingency plan Well preparation – gauge cutter Measurement while perforating Technical and risk evaluation resulted in the weep-holes perforation method being selected for this project. The high-pressure zones on the subject well were step-by-step perforated based on a detailed plan. At the last safe perforation run that resulted in a huge well shut-in pressure increase, the well was production tested. The production test indicated the added perforations at this well operation boosted the well production by about 100%.