Country-Level Gas Production Optimization at Decline Stage Without Investment Using a Digital Twin

Abstract YPFB, the Bolivian State Oil Company, needed to secure gas production volumes for local and export markets at a decline stage of major gas production fields. Naturally fractured major gas fields in the Bolivian Sub Andean Basin did not behave as expected and faced challenges at decline stage, as hydrocarbon flow from reservoirs to sales points needed to be optimized in a cost-effective manner due to declining well productivity. Backpressure effects started to constrain the ability of wells to unload the bottomhole and production line from accumulated liquids and reservoirs suffered lower pressure drawdowns and wellbore skin damage. The best fit-for-solution to overcome such conditions is represented by field compression projects, which generally in Bolivia are not included in the original development plan as part of the Commerciality Assessment. YPFB needed then to evaluate the feasibility of compression projects at decline stages by proposing alternatives for gas production increase and savings in compression projects prior to sizing compression power. An extended digital twin including wells, gathering systems, gas processing plants, sales gas pipelines, midstream liquefaction plants and export/local pipeline systems for major gas fields in Bolivia allowed to periodically analyze changes in surface conditions to overcome these challenges and obtain significant increases in gas production on a country level -at no cost-, as well as savings in field compression projects, by reducing well backpressure starting at the sales point. Increases in gas production of 8 and 10 % were reached in the San Alberto and San Antonio Fields, respectively, prior to the implementation of field compression projects in 2015 and 2018, when processing plant design operating pressures were reduced by 350 psi. These production increments against a baseline case represented additional incomes of 280 MMUSD a year for both fields when taking the sustained additional gas and condensate production volumes through one year at gas and liquid prices for exports and local markets, respectively.