Successful Placement of an Advancing Sand and Fines Control Chemical as a Remedial Sand Control,using Subsea Flow Lines from an FPSO

摘要

The ENI Nigerian subsidiary operates a subsea field located in the north western sector of the Nigerian offshore deep-water,is an oil and gas producing field.The production is from subsea wells which are directed to a Floating Production,Storage and Offloading vessel(FPSO).All the wells in this field require sand control measures in the reservoir section from the onset to prevent sand production.Sand control in the field is challenging and various methods(gravel pack,frac pack and expandable sand screens)have been used.Conventional sand control integrity has failed in one of the wells,compromising production rate and exposing subsea asset to risks related to sand production.Compared to heavy workover required for primary sand control application,an advancing chemical treatment bullheaded through the subsea flowline and the production tubing provided a unique,highly economical,and effective solution to this challenging problem.The product effect creates an ionic attraction between the sand grains and fines, using non-damaging water-based fluid.The chemistry mitigates sand production,reduces or stops fines migration and increases the Maximum Sand Free Rate(MSFR).After pumping chemical treatment through a 4.2 km flow line in the failed frac packed completion,well returned to production with minimal sand presence,less than 24 hours NPT and eliminating the need for re-completion.This was the first time the chemical had been pumped from an FPSO and through subsea flow line.This paper discusses the planning,execution,post job analysis and lessons learned.