This paper presents the application of model-based optimization on production systems consisting of clusters of high water cut low GOR (gas oil ratio) oil wells producing by ESP (Electrical Submersible Pumps) which converge into a multi-branched surface gathering system. The optimization strategy consists in modifying individual ESP frequencies in order to achieve higher oil production while honoring multiple operational constraints.
The optimization methodology is successfully demonstrated in two scaled-down synthetic cases and one field case. Furthermore, some of the data of the modeled cases is included in the appendix calling for benchmarking with other models and optimization programs.
The production of individual oil and gas wells in large fields is often piped to the field processing facilities or to the field export points through a surface gathering system. The flow system is normally arranged as a converging network of material streams. The layout of gathering systems in oil and fields may differ considerably depending on the field layout, its wells and facilities spread, and on the geographical environment such as offshore platforms, subsea production, small land based fields or large land based fields.
The production of individual wells (fluid sources) in the cluster is gathered and commingled in a production manifold, normally adjacent to the wellhead cluster. In large multi-cluster fields, with a single separation and processing plant, the clusters are piped and merged at junctions into sub trunklines (feeder lines), and main trunklines that commingle and produce the entire field, or a major segment of the field, to the processing plant (Fig. 1).