Analysis of Produced Gas Composition and Processing Requirements at the Odidi Gas Plant, Delta State, South South Nigeria

Produced gas associated with crude oil production in the Niger Delta has historically been subject to flaring or limited commercial utilisation, but increasing regulatory and economic pressure has accelerated gas processing infrastructure development. This study analyses the produced gas composition at the Odidi Gas Plant in Delta State and evaluates processing requirements for commercial gas conditioning. Gas samples from twelve producing wells in the Odidi Field were collected at the wellhead and subjected to full compositional analysis by gas chromatography through C10-plus fractions. Hydrogen sulphide and carbon dioxide contents were measured using dedicated infrared and Drager tube methods. Results indicate a methane content ranging from 76 to 89 mole percent, with ethane-plus liquids content between 4.2 and 8.7 gallons per thousand standard cubic feet, classifying the gas streams as rich gas suitable for liquid recovery. Hydrogen sulphide concentrations of 15 to 45 parts per million in gas from the deeper reservoir zones require amine-based sweetening upstream of compression. A process flow diagram incorporating inlet separation, amine sweetening, glycol dehydration, and lean-oil absorption for liquid recovery is proposed and sized to handle a design feed gas rate of 120 million standard cubic feet per day. Capital and operating cost estimates are developed for the proposed plant configuration, with an economic evaluation indicating project payout in under six years at current Nigerian Gas Transmission Tariff rates. Keywords: produced gas composition, gas processing, Odidi Gas Plant, Delta State, gas liquids recovery.