Multi-Lateral Wells with Downhole Water Control and Disposal in Heavy Oil Reservoirs with Bottom Water – A Case Study

Abstract

Abstract In heavy oil reservoirs with bottom water drive, water coning severely hampers well productivity and oil recovery, due to excessive water production. Moreover, conventional enhancement techniques such as thermal and/or gravity-assisted production methods do not solve the problem of handling and processing large volumes of produced water. In this paper, we study feasibility of a new well completion and production technique using Multi-Lateral Water Loop (MLWL). MLWL wells are multi-functional installations that feature three horizontal legs on the same vertical plane and at different depths. The top leg drains the oil payzone, the middle one controls water cresting by draining the aquifer beneath the oil-water contact (OWC), and the bottom leg injects the drained water deeper into the same aquifer. The top horizontal lateral provides maximum reservoir contact (MRC), low pressure drawdown and high production rate thus enhancing recovery. The middle lateral makes the oil production water-free, while the bottom lateral keeps the water underground without lifting it to the surface. Using a reservoir simulation model of MLWL and a conventional horizontal well in a West African heavy oilfield, we study MLWL well design and operation that would make the technique superior to conventional horizontal well production in this oilfield. The results demonstrate the MLWL potential for increased production rate and ultimate oil recovery and the economic advantage of handling formation water in-situ. The study also explains how the MLWL system improves the recovery mechanism by mobilizing oil throughout the whole drainage area rather than in the well's vicinity. Furthermore, optimum operation conditions for water looping system are identified where economic limit is met and inverse coning avoided. The results show superiority of wells with downhole water drainage over conventional wells. Morover, the MLWL wells have additional advantage of prolonged economic life and, therefore, high profitability.