TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractManagement of mature oil fields requires accurate formation evaluation information. The ability to acquire essential data through casing adds a new dimension to reservoir characterization and affects the reservoir development of a mature oilfield like the Bahrain field. New logging tools and technology fill the gap in evaluation, especially for monitoring water saturation changes over time and for detecting bypassed oil pockets across the zone.In this paper we present the results and validity of a logging through casing run in a depleted well completed in a sandstone reservoir in the Bahrain oilfield. The reservoir has a complex lithology of high-permeability sandstone with thin interbeds of siltstone and shale, erratically deposited but prolific in oil production. The objectives of the data acquisition were to monitor oil depletion through casing and to study the effect of lithology on the water encroachment pattern across the zone.In this paper we describe the interpretation procedures and data validation of the information obtained from an advanced suite of logs run through casing. The paper also focuses on how this new information has resulted in a review of potential further development of this pay in one part of the field.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Aruma zone in the Bahrain field is a shallow dolomitic limestone with vugs filled with heavy oil and tar. Due to difficult fluid and rock properties, the reservoir was deemed unproductive and the zone was routinely cased off to reach deeper productive horizons.Bapco has recently launched a project to investigate the producibility of the zone under advanced IOR techniques and lifting technology. A fluid and rock data acquisition program was initiated to characterize the reservoir, which included advanced logs and core acquisition. Wellbore instability made both log and core acquisition challenging. This paper discusses the experience with the rock characterization using advanced integration software.Due to the large volume of data acquired from a variety of advanced logs and core, it was a challenge to efficiently and effectively integrate all data and ensure utilization of every piece of information. In this paper, we demonstrate the importance and value added by using a system that facilitates integration, manipulation and simultaneous wellbore visualization in 2D and 3D Canvasses in an interactive environment. We illustrate the positive impact of such visualization on data quality assessment in zones of borehole induced artifacts.We demonstrate the several interactions that serve to add value to the acquired information. We also discuss the impact that such visualization and interaction capability has on the accuracy of decisions made on the well and on the validity of the characterization of the reservoir rock in the near wellbore region