Addressing Realtime Formation Evaluation Data Transmission Challenges with Microbubble and Hollow Glass Sphere Mud System - A Case Study from India

Abstract Objectives/Scope The paper outlines the obstacles encountered during the initial implementation of Hollow Glass Sphere (HGS) and Microbubble Mud Systems for formation evaluation data transmission while using mud pulse telemetry in Western Offshore India. The oil and gas operator encountered significant challenges when drilling and assessing formations in directional wells within these low-pressure and depleted reservoirs. HGS and Microbubble Mud Systems were employed to decrease the density of drilling fluids to prevent and address losses while drilling through a producing reservoir section with low pore pressures. Methods, Procedures, Process In an effort to address the issue of significant or complete loss of drilling fluid during operations in a low-pressure reservoir, a low-density mud system was introduced with a density ranging between 6.3 to 7.5 pounds per gallon (ppg). However, the inclusion of micro-bubbles or hollow glass spheres in the drilling mud resulted in poor compression, substantial distortion, and weakening of the mud pulse telemetry signal. As a result, the real-time logging-while-drilling (LWD) log lacked data density, diminishing its value to the client. To rectify this, an in-depth analysis was conducted, considering factors such as pump efficiency, flow rate, mud pulse telemetry principles, and pulser design, leading to the development of a novel technique aimed at delivering high-density formation evaluation LWD Data. Results, Observations, Conclusions Identifying the factors that posed limitations and implementing strategies to mitigate risks were pivotal actions taken to minimize the risk of data loss and ensure a continuous and uninterrupted stream of logging-while-drilling (LWD) data for real-time decision-making by the operator. This involved servicing the pulser, making changes to pulser design, and enhancing the accompanying software, resulting in the capability to transmit mud pulse data at rates of up to 20 BPS in place of 5 BPS initially. The modified configurations of the mud-pulse telemetry module proved highly valuable in delivering an uninterrupted LWD log with a sufficient data density, thus meeting the requirements of the operator’s subsurface team. Novel/Additive Information The paper ends with concluding the best practices which should be incorporated to deliver quality data. This pulser and telemetry system can be combined with any LWD services including NMR, formation pressures and electrical imaging while drilling.