Improving Well and Reservoir Management Practice Through New Flow Control Philosophy that Prolongs the Life of Production Wells Affected by Water Breakthrough in A Giant Carbonate Oil Field, Abu Dhabi, United Arab Emirates

Abstract

X Field located in the United Arab Emirates has been developed since 1970's by waterflooding as secondary recovery strategy. As water front advances into oil bank, the well operation practice commonly adopted in many fields for oil wells cutting water has consisted in reducing choke aperture in an attempt to control the water cut trend. However, in wells producing moderate to high water cut, this practice has proven to generate excess water settling in the bottom of the wellbore leading to premature inactivation of the wells. The reservoir Z in the north of X Field, is a black oil block operated by peripheral and pattern waterflooding. The production wells have been operating by natural lifting since first oil and will continue in natural flow until the Artificial Lift projects are commissioned within a few years. Meanwhile, the field production plateau has been increased arising challenges of production sustainability due to higher risk of acceleration of water breakthrough and consequently higher number of wells becoming inactive earlier. This led to re-assess the Well and Reservoir management strategy to define improved practices oriented to maximize the natural life cycle of wet wells and ensure the compliance of the field production quota. As a result, a new well management approach was devised and adopted to identify and optimize at the earliest stage, wells potentially affected by water loading mismanage. Conceptually, this new practice consisted in comprehensively analyzing well operating conditions, which ultimately generated a flow operating window that improved the multiphase flow performance in wellbores, minimized water slippage avoiding it to settle down and its associated problems, whilst respecting the compliance of technical guidelines for optimum reservoir management. Based on observations and data gathered from portable testing jobs, saturation logs, PLT and production monitoring; a methodology referred in this work as Critical Flow Analysis, has been successfully implemented in several naturally flowing wells with water cuts ranging from 15 – 40 % in Reservoir Z in X Field, which resulted in prolonged natural life, extra oil recovered, and avoided the negative impact of inactive string count on the Field Management KPI. The Critical Flow analysis has been a comprehensive well management evaluation and operation philosophy in Reservoir Z which helped to manage more efficiently and in cost-saving fashion the performance of oil wells located in high risk areas, in addition to contribute with stablishing best practices for well and reservoir management that could be extended to analog fields in the area.