Study Analyzes Through-Tubing Sand-Screen Application Offshore Malaysia

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 220610, “Performance Analysis of Through-Tubing Sand-Screen Application Offshore East Malaysia,” by Zulkifli B.M. Zin, Onn Lin Ling, and Ashvin A. Chandrakant, SPE, Petronas, et al. The paper has not been peer reviewed. _ Through-tubing sand screens (TTSS) are used routinely by the operator to mitigate sand production in offshore wells. A smaller outer-diameter wire-wrap or premium mesh screen is retrofitted inside or set at the end of an existing tubing to filter sand ingress from a failed primary sand-control zone. Given the many recurring annual installations performed by the operator, a study was conducted on past TTSS installations to evaluate performance and develop a workflow with the aim of improving future installations. TTSS Performance Analysis One hundred and twenty-five TTSS installations have been made in offshore wells in eastern Malaysia since 2009. The remedial screens are installed in various types of completions. Parameters from these TTSS installations, including screen type, length, opening size, and installation depth were collected and analyzed against net service life in a crossplot to identify any correlations between the parameter and the installation performance. Methodology. The following steps were used to conduct the TTSS performance analysis: - Data were extracted from well-intervention histories and wellbore diagrams to determine installation and retrieval dates for each TTSS across eastern Malaysia. Additional data, such as TTSS design, reservoir information, installation depths, deviation, distance, opening size, and screen length also were determined. - Data from a production database were analyzed to calculate net service life and net effective life by determining production data, failure cause, failure date, and well downtime for each installation. - All data were consolidated into dashboard visualization for further analysis to establish correlations between various parameters, such as screen opening size, screen length, and type of installation system. Selected parameters were analyzed to find any correlation with net service life, namely screen opening size, total screen length, and distance between top perforation and TTSS installation depth. Net Service Life and Failure Causes. The net service life of a TTSS was defined as total production days from installation until retrieval. The average net service life of a TTSS installed across eastern Malaysian wells was found to be 13.94 months. Service life was categorized into more than 6 months and less than 6 months. The duration of 6 months was selected as a cutoff to categorize low-performing installations. Out of the 125 installations, 72 installations (58%) lasted more than 6 months, while the remaining 53 installations failed within the first 6 months. The failure cause of each installation was determined on the basis of production, sand-count history, and, in limited instances, the condition of retrieved screens. The breakdown of the failure causes was 40% high sand (50 installations), 18% production impairment (22 installations), and 42% unidentified (53 installations). A high sand failure was defined as either a single occurrence of a high sand spike or three consecutive high sand counts above the normal average, which could be an indication of screen erosion or oversized screen openings. Conversely, production impairment failure was defined as the production rate dropping by more than 50% compared with the rate before TTSS installation, which could be an indication of screen plugging or undersized screen openings.