Evolution of Production Logging Technologies and Capabilities: In Quest to Know the Unknown, A Brownfield Case Study, Mumbai High, ONGC Western Offshore

摘要

Production logging traditionally has been used to describe the flow characteristic of a well. Over the years with the advancement of the technology, for the techno economic success, deviated and horizontal wells have been drilled. Application of highly deviated and horizontal wells for field development primary recovery is now a worldwide practice. Diagnosing production problems in a near horizontal environment is a herculean task; complex flow regimes in highly deviated well aggravate complications. At the same time, with advancement in completion system design, it has become imperative to evaluate the effectiveness of the new completion design. Unfortunately traditional production logging techniques have not been successful in these conditions. One of the key issues in diagnosing production problems is detecting and distinguishing hydrocarbons in high water cut wells with water phase flowing as continuous medium at the low side and dispersed hydrocarbon phase at the high side of wellbore. Technologies like the digital entry fluid imaging tool and gas holdup optical sensor tool have proven to provide accurate results. For horizontal and highly deviated wells where recirculation, crossflow, and phase segregation further complicate the flow behavior, complete imaging of the wellbore is needed to characterize the wells. In brownfield scenario, the complications aggravate and may require real-time decision making and intensive data analysis. Some of the typical brownfield issues are scale buildup due to immense water injection for pressure support, which is required for efficient oil displacement, complex fluid flow regime, recirculation due to insufficient lift, and casing damage resulting in unwanted formation water entry. The study provides the most prolific summary and guide for case studies, success stories and lessons learned from the Mumbai High field in the last decade; evolution of the production logging tool from the most standard unit to multipoint digital entry fluid imaging, gas holdup optical sensor tools to identify and distinguish between the three fluid phases. The paradigm shifts towards the key technologies like flow scan imager to evaluate the complex borehole fluid behavior, flow regimes identification is also presented in this paper. The results derived are indispensable for future well placement campaign.