This document is an expanded abstract.

Summary

Excessive amount of water with produced crude oil has been a continuing problem in conventional petroleum production technology worldwide. In naturally fractured reservoirs (NFR), the problem of water production (i.e. water coning and/or channeling) is more severe than conventional hydrocarbon reservoirs. In fractured reservoirs, fractures are the main conduit for oil flow within a reservoir. However, in the presence of bottom water, the fractures channelize water rapidly toward the oil producing wells causing large amount of bypassed oil. This paper studies the feasibility of Downhole Water Sink (DWS) technology in fractured system experiencing high water productions due to water coning/channeling.

DWS technology is a dual-completion technique practiced to suppress bottom water invasion hydrodynamically using segregated co-production of oil and water from the payzone and the bottom aquifer, respectively. As the bottom (water sink) completion drains the bottom water from around the well, the top completion produces oil with less (or no) water cut resulting in higher oil rate and recovery. To date, feasibility of DWS has been tested theoretically, numerically, and experimentally; and supported by field-trials in conventional gas and oil (light and heavy) reservoirs with various completion configurations (vertical, horizontal, and multi-lateral). Fortunately, deployment of DWS well in fractured systems has proved to be feasible and potentially equivalent to its effectiveness in non-fractured reservoirs.

Introduction

Premature water production problem is more troubling in naturally fractured reservoirs (NFR) than in non-fractured reservoirs. In NFR, fluid flow behavior through fracture conduits versus rock matrices substantially differ. The complexity of fluid flow extends beyond proper characterization of fractured systems, which is uneasy task. Performance of oil wells in NFR require good understanding of the nature of fractures. When watering problems arise in fractured systems, mitigation of pre-existing water productions grows into a more challenging subject. Oil industries have, generously, invested times and resources in attempts to control, manage, and dispose unwanted water productions.

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