Case Study: Economic and Technical Analysis of Retrograde Gas Processing on Offshore Platforms

Abstract

Recent discoveries of retrograde gas fields in Brazilian deepwaters are more distant from the shore, and away from available infrastructure for processing gas. In this scenario, processing the gas offshore becomes an important challenge, equipping these fields to become viable producers. The present study aims to evaluate the economic motivation for this concept by comparing two scenarios of retrograde gas production. The scenarios consider processing the gas to sales based on: 1. Production offshore and gas export to a new built onshore processing plant, and 2. Production and treatment of the gas offshore. The second scenario considered three hydrocarbon dew point treatments: Joule-Thomson, Turboexpansion, and Refrigeration. The economic assessment used the software QUE$TOR®. Following the assessment, process simulations used ASPEN HYSYS® to perform the technical evaluation. The economic results were promising despite connected strongly to gas price. The simulation results indicated that the use of dew point treatments are viable but depend on feed gas composition.