Well performance optimization for gas lift operation in a heterogeneous reservoir by fine zonation and different well type integration

Abstract

In this study, an integrated optimization procedure was proposed for well performance analysis in a heterogeneous oil field from southwest Iran. Proposed integrated strategy optimizes well performance in an iterative manner, while fluid properties, geological and petrophysical data were analyzed separately by new advanced methods. Subsequently, integrated solution was introduced by integrating various well types geometry and fine zonation of the target formation. Combination between each zone and each well type was based on three potential oil bearing zones predefined by well log data analysis. Target formation, the Sarvak formation limestone, was divided into 10 different zones and much more subzones according to the geological and petrophysical data. Afterwards, 17 wells with various geometries were modeled in the upscaled reservoir model. Fluid properties and reservoir characteristics were also obtained and analyzed from different samples taken from target formation. Results of applying the proposed integration strategy defined that the maximum production rate occurs while water cut does not exceed 10%. Performed analysis also suggest 15 MPa as the optimal value of the surface gas lift pressure and state that the gas oil ratio should not exceed this ratio at the flowing wells bottom condition. Sensitivity analysis on tube size expresses 4.67-inches tube as the optimum value. Meanwhile, sensitivity analysis on flow rate represents that optimal value of this parameter shows high sensitivity to changes in production index. Results showed that 7% change in production index will make 4% changes in optimal gas flow rate value.