Deterministic Approach Towards Well Intervention Candidate Selection & Quantification of Parameters in Esp & Jet Pump Wells

Abstract

This paper aims to describe a model created to determine various important parameters to monitor oil producer wells with different artificial lift types: Jet Pump (JP) and Electric Submersible Pump (ESP) of Mangala & Aishwarya fields. The fields contain medium gravity viscous crude (10-40cp) in high permeability (1-5 Darcy) sands. In order to overcome adverse mobility ratio and improve sweep efficiency, polymer flooding was adopted. As the Polymer flooding proceeded, polymer breakthrough in producer wells was observed. The major challenges faced in producer wells is polymer/scale depositions realized during well interventions. This issue has surfaced in field due to polymer breakthrough in oil producers and mixing of produced polymer concentration in well fluid with scales, wax or other bivalent ions. Major concerns due to polymer deposition included, fouling of artificial lift system, decrease of well uptime, jet pump (type of artificial lift) & ESP efficiency decrease. ESP & Reverse jet pumping are the major artificial lifts for the field, where power fluid is pumped through annulus and production is taken through tubing. With continued jet Pump fouling due to Polymer, wax & scale agglomerate, well uptime decreased. During jet pump redressing, polymer deposition has been observed in the body X-over (reservoir liquid path), check valve assembly, throat and spacer nozzle to throat inside jet-pump. Thus, a necessity was felt to address the issue with a proactive approach. Continuous chemical dosing method was tried and proven successfully, but it was not cost effective. Hence empirical based modelling was required which can quantify these parameters to plan for well intervention & well clean-up jobs. The developed model is "intelligent" and determines various parameters like – Productivity index(PI) of jet pump well without having suction pressure data, jet pump nozzle loss coefficient, ESP pump efficiency (ESP wear), annulus deposition & debris deposition in tubing reducing effective ID of annulus & tubing respectively. The model calculates from every newly logged Multiphase flowmeter rates, water cut, Annulus pumping pressure & tubing head pressure (THP) events and determines its approach of marking the risk levels of a well. With continued JP/ESP fouling, tubing deposition & PI drop due to Polymer, wax & scale agglomerate, well uptime & production rate is decreased.