Integrated Optimization Process Advances Steamflood Performance

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 196249, “Advancing Steamflood Performance Through a New Integrated Optimization Process: Transforming the Concept Into Practice,” by Henri Silalahi, Muhamad Aji, SPE, and Afrilia Elisa, SPE, Chevron, et al., prepared for the 2019 SPE/IATMI Asia Pacific Oil and Gas Conference and Exhibition, Bali, Indonesia, 29-31 October. The paper has not been peer reviewed. Duri Field in Indonesia is the largest active steamflood project in the world. The field produces 73,000 BOPD, and 10,000 optimization jobs are executed annually to support base production. The operator identified an opportunity to implement a new process to improve the quality of reservoir analyses, define short- and long-term reservoir depletion strategies, and increase the ability to develop a prioritized queue of executable opportunities to increase production. Introduction Duri Field was discovered in 1941 in the central Sumatra Basin in Riau Province. The first production-optimization effort, in 1967, used cyclic steam stimulation. That led to a successful steamflood pilot trial in 1975 and implementation of a full steamflood areal expansion in 1985. Thirteen production areas currently exist in Duri Field as a result of steamflooding. Geological Background The geological setting of the field involves an anticline structure 20 km long and 14 km wide that covers more than 21,000 acres. The historical tectonic process results in shallow reservoir depths. The field is composed of multiple sand deposits of a tidally influenced estuarine depositional system. The reservoirs are characterized by stacked sand lobes with a total thickness of approximately 240 ft, porosity ranges from 25 to 35%, and relatively high permeability of 600 md to 2 darcy. As a giant field, Duri had an original oil in place of approximately 5 billion bbl. The oil is characterized as heavy, with gravity from 17 to 22 °API and high oil viscosity (300 cp) at 100°F.