Multi-lateral wells are being employed to improve vertical sweep by enhancing productivity/injectivity from relatively tight sub-layers of the reservoir. In addition, different direction and orientation of the drilled laterals improve areal sweep. To optimize the development plans for multi-layered reservoirs with varying permeability, quantifying the contribution across each sub-layer is necessary and can be achieved by production logging. These surveys are being conducted in Zakum Development Company (ZADCO) as part of the field development plan.
Production logging data from multi-lateral wells are often difficult to interpret due to multi-phase flow. A variety of flow patterns exist in multi-phase production. These flow patterns can vary within a particular wellbore, even at constant flow rate. Quantitative analysis is difficult in such cases sometimes, however qualitative information can be inferred. The conventional production logging technology has its limitations in analyzing the data. The analysis is dependent and based on several factors. Some of these factors are drilling/completion and the wellbore damage as a result of drilling fluids, stimulation and cleanup, the production logging tool and analysis techniques.
This paper highlights the details of above factors and how these can be handled. Also, two case histories are included to indicate the problems observed.