Perpustakaan Digital ITB

Flowing Through Annulus (FTA) is an abnormal production condition in which produced fluids flow through the tubing–casing annulus instead of the intended production tubing. This phenomenon frequently occurs in Electric Submersible Pump (ESP)-operated wells with high free gas content and is commonly associated with gas-induced ESP performance degradation. Well A-02, located in Bojonegoro, East Java, Indonesia, exhibits this condition while producing 5,971 BLPD with a 91.78% water cut and a Gas–Oil Ratio (GOR) of 1751 SCF/STB. The high free gas fraction entering the ESP intake significantly reduces the pump's hydraulic performance, leading to the occurrence of FTA. This study aims to evaluate the degradation of the existing ESP, analyze its relationship with FTA, assess the capability of the existing ESP to satisfy the Total Dynamic Head (TDH), develop several ESP redesign scenarios, and determine the optimum configuration for minimizing FTA. The Inflow Performance Relationship (IPR) was constructed using Vogel's method, while the Tubing Performance Relationship (TPR) was developed using the Hagedorn and Brown correlation. ESP performance and redesign scenarios were evaluated using PIPESIM simulation and hydraulic calculations. The results indicate that the existing ESP is unable to satisfy the required TDH of 2944.82 ft, as the actual pump head decreases to 2,812 ft due to gas-induced degradation, corresponding to a degradation factor of 0.43. Five redesign scenarios were evaluated, including stage addition, pump type replacement, operating frequency optimization, gas separator implementation, and a combined redesign scenario. Among these, the combined redesign, consisting of an S8000N ESP operating at 60 Hz with a gas separator efficiency of 95%, provides the best technical performance. The redesigned system operates at 5966.7 STBD, reduces the gas formation volume fraction at the pump intake from 0.89 to 0.28, and decreases the required number of pump stages from 75 to 65. These improvements restore the ESP's hydraulic capability to satisfy the TDH requirement and effectively minimize the occurrence of Flowing Through Annulus