Sand Management Strategy in Offshore Gas Field in the Gulf of Thailand

Abstract

This paper examines the sand production management strategies practised by Carigali-PTTEPI Operating Company (CPOC) to minimize the impact of excessive sand production on the processing facilities and well integrity as sand production from producing wells continues to increase. Sudden well interruptions could jeopardise the daily production delivery hence require all risks to be mitigated at early stage includes risk from sand production. Gas reservoirs in CPOC operated fields were developed with monobore completions without active sand control. CPOC adopts the passive sand management approach, where sand is allowed to be produced to surface and later managed on the top-side facilities. The objective is to manage the produced sand using existing facilities and minimize the process upset/downtime. CPOC Sand Production Management consists of two main parts, Monitoring and Remediation. Two types of monitoring are done: Sand Production Monitoring and Corrosion/Erosion Monitoring. Ultrasonic Sand Detector has been used as the main tool for Sand Production Monitoring. Ultrasonic Testing (UT) has been carried out for all production flowlines as part of Corrosion/Erosion monitoring. Effective monitoring has become the enabler for proactive remediation actions. The remediation focuses on two areas: minimize sand production from wells (via MSFR/MASR-Maximum Sand Free Rate/Maximum Allowable Sand Rate), carry out water shut off, sand failure analysis etc.) and improve the integrity and reliability of processing facilities through upgrading activities. The interpretation of sand production from Ultrasonic Sand Detector allows qualitative and quantitative assessments of sand production and operational instruction for flowing wells via MSFR/MASR. In addition, UT survey is used to estimate the flowline remaining life. Proactive remediation of topside equipment is done in a timely and effective manner using Ultrasonic Sand Detector's data together with other inspection data. CPOC has also upgraded several topside equipment to improve the efficiency of sand removal, equipment integrity and reliability. This topside upgrade includes main processing platform sand removal upgrade, slug catcher cleaning, flowline wrapping, etc. This multidisciplinary collaboration since 2014, which integrate the monitoring of sand production from the wellbore with remediation activities of the downstream processes, has allowed CPOC to safely operate and achieve production target without loss of containment. The sand production management strategies practised by CPOC not only allows the company to safely operate and achieve production target, it also enables the use of "slimhole monobore" completion which is economical and practical well design without the need for conventional downhole sand control, and results in well cost of <10 MMUS. This type of field development and sand production management has become a standard technology in the Gulf of Thailand.