Viscosity Versus Accuracy – Flow Control Feasibility Workflow in Polymer Flooding

Abstract

The use of horizontal wells for injection and production to help maximise the sweep efficiency and economic recovery; especially for recovery of viscous oil in offshore environments. Flow control devices (FCDs) are readily used to control the flow along the well in conventional recovery operations leading to improved recovery efficiency. The benefits of polymer flooding and FCDs has been well demonstrated, however the combination of the two technologies has yet to be fully realised. The cause of FCDs not being as utilised in polymer injection application is due to the severe degradation of the polymer through devices. This paper provides a workflow used to determine the benefits of a well planned and executed polymer injection complemented by the optimum flow control strategy. The main focus will be on demonstrating the relative weights in the objective function of optimising the sweep efficiency with the cost of reduced polymer quality. This workflow will allow a number of strategies to be studied, such as the impact of well types, well placement, well lengths, FCDs and polymer viscosities. The impact of polymer viscosity reduction in an injector well with FCDs is of particular interest. Hence the trade-off of the polymer degradation and the ability to get the required polymer quantity in the various segments of the well will be described. The feasibility of polymer flooding with flow control is a viable alternative for classical enhanced oil recovery (EOR) but the decision whether or not to implement it has to be based on prudent analysis and decision making process. Hence the study highlights the importance of understanding uncertainties with control as well as those associated with reservoir and geology.