The Diagnostics and Recompletion Strategy of a Well with Sustained Casing Pressure

Abstract

Well sustained casing pressure signifies failure in the barrier envelop of any well and results in situations where pressure is observed or recorded in the annuli of a well and this pressure usually rebounds after bleed down. This phenomenon is a precursor to environmental and safety risk to the global oil and gas industry and presents a challenging situation that requires monitoring to understand the severity and management strategy. It is assessed to be a well integrity issue due to noncompliance to well barrier concept. It has become increasingly critical to address wells with sustained casing pressure (SCP) in view of the regulations guiding the industry and the operating environment which is experiencing an escalation of third-party activities. A bridge of well safety portends serious safety, health, environmental, operational, and integrity risks. Well PO-21 was completed as a single string, horizontal completion in the Q-10/PO-20 reservoir in 2004. Although, the well exceeded the production targets, it was subsequently shut-in in 2007 due to SCP. The initial well work attempts were carried out but were ineffective in resolving the SCP concerns: the well works carried out to isolate the casing pressure include tubing hole finding and setting of pack-off to isolate the holes. These activities could not resolve the sustained casing pressure issues with the well until a comprehensive analysis of the well, using a production logging tool comprising of noise and temperature log was deployed which gave a better understanding of the challenges of the well. A Major Rig Work Over (MRWO) was subsequently carried out on well and production was restored. The well has continued to produce. This paper sets out to explore the holistic study of well PO-21: the initial well construction – drilling (casing, cementing, etc.,) and completion (lower and upper) design and operations. It will also showcase the production and nature of the problem observed during the production, the evaluations, and diagnostics carried out to isolate the source of SCP. The step-by-step solution approach in eliminating possible sources will be discussed based on the identified issues with the well using acquired data. The paper will also focus on the MRWO operations, and the several challenging situations encountered which necessitated a management of change from the planned recompletion strategy in response to the observed well condition. The well was successfully recompleted with no loss of containment and several lessons were learnt.