Successful and Efficient Revival Strategy for High Deviated Gravel Pack Completion Well with Liquid Loading Issue Due to Unplanned Shutdown at Offshore Mahakam Field: NB-X Case Study

Abstract

Abstract The objective of this paper is to present the well revival strategy for gravel pack completion with liquid loading issue. Well NB-X is a high deviated gas well which was completed with 2 Sliding Sleeve Door-Gravel Pack (SSD-GP) zones and tubingless section. Since this well is a gas well with high water production, sudden unplanned shutdown can lead to a liquid loading issue. Revival well strategy by offloading the well to atmospheric was still not able to recover production as before the shutdown due to the high liquid column in the well. Therefore, a well intervention operation is needed to revive the well. The strategy was initiated by conducting a bottom hole monitoring survey to identify water sources. Production Logging Tool (PLT) was used to precisely monitor pressure, temperature, water holdup, and fluid rate along the wellbore for further water source and production allocation analysis. Once the water source zones have been identified, GP zone change for water shut-off (WSO) operation was requested. There are several means to execute zone change and unloading that are commonly used in Offshore Mahakam field each of which has selective economic consideration based on the expected well potential. A comparative study both for zone change (slickline, electricline tractor-stroker, and coiled tubing) and unload (N2 injection with coiled tubing) is performed to decide the most efficient way to revive the well. Operations started with a slickline zone change to close the water zone followed by production logging, however due to high inclination, it was found that the target zone was not fully closed. Based on the comparative study, zone change and unloading with coiled tubing (CT) was the most efficient strategy with cost saving for about 83% compared to the other means. Zone change and unloading can safely and efficiently be performed with CT followed by a production test via Multi-Phase Flow Meter (MPFM) while keeping the CT string inside the tubing to perform as a velocity string until gas production target is obtained. Well revival strategy on well NB-X was proven to be able to revive 100% well production of 18 MMscfd within a very short time period from the shutdown event. Comparative study between coiled tubing and electricline tractor-stroker for zone change and unloading was critical since the offshore area have many challenges such as unpredictable weather, limited availability of transportation units, efficiency of setting up units from and to the platform, and also the callout cost both for the equipment and personnel between the two which ends with the selection of coiled tubing as the most efficient way for this case.