Successful Underbalanced Drilling Campaign with Rotary Steerable System in Western Offshore India

Abstract In an underbalanced drilling scenario, an operator in India needed to deploy a Rotary Steerable System (RSS) alongside N2 injection to maintain precise directional control. Within this Managed Pressure Drilling (MPD) setup, an additional obstacle involved ensuring uninterrupted data transmission through positive pulse telemetry while drilling with Dual Phase fluid. This Dual Phase fluid leads to a reduction in mud density, potentially leading to a weakening or loss of signal strength. Additional Challenges involved delivering precise well profile and good hole cleaning. Extensive pre-job and pre-study efforts were invested in preparing and configuring tools to withstand challenging underbalanced drilling (UBD) conditions while also ensuring the real-time delivery of high-quality formation evaluation data. The conversation encompassed tool configuration, specifically emphasizing the flow range, as well as the immediate steps required to ensure accurate directional control with RSS. The aims of integrating underbalanced drilling (UBD) technology in the designated field encompassed preventing reservoir damage to boost oil production and recoverable reserves from the wells. Simultaneously, it aimed to enhance drilling performance in the reservoir section by eradicating mud losses, leading to an increase in lateral length and improved reservoir contact. Realtime geosteering was done by the operator with the help of Quadrant Gamma, Resistivity, Density and Porosity Data to be in sweet zone for entire section of the lateral. Drilling was done with base oil and with produced crude oil after the well started flowing because of Inflow testing. Three stage inflow tests were carried out with RSS tools in the well saving the operator one to two rig days and therefore continuing drilling with produced fluid. The paper presents a case study for 4 wells campaign where RSS along with Logging While Drilling tools was used in underbalanced Conditions. Also, the paper compares the improvement in strategies which was carried out in-situ and as a lesson learnt for future wells.