Abstract

Since 1956 the Wafra 1st Eocene Reservoir in Kuwait has significant heavy oil from dolomitized peloidal grainstones and packstones/wackestones interlayered by nodular to tabular evaporites. As primary recovery will likely be low, options are being evaluating for a possible full field steamflood project to improve oil recovery. As part of this evaluation a multidisciplinary team was formed in January 2009 to help provide a detailed and data driven view of the historical performance of the reservoir.

In an effort to address all of the potential dynamic and static contributions to performance throughout the history of the 1st Eocene reservoir field the Historical Assessment of Reservoir Performance (HARP) incorporated several sub-studies including: 1) data collection and uncertainty review, 2) data base design and well by well production review, 3) field wide production trends, 4) historical operations, 5) pressure mapping and 6) a water movement study. These inter-related studies have provided a data substantiated view of reservoir performance to date.

The first study, data collection and uncertainty review, identified key uncertainties and prepared a comprehensive data acquisition program that could help address them. The second study, data base design and well by well histories, successfully incorporated paper and digital well data into one Access™ database that interfaced with ArcGIS™ in order to easily perform spatial analysis on the historical data. The third study, field wide trends, analyzed production through time to determine if trends existed in an areal and/or vertical sense. For this effort a Spotfire™ database (connected to the Access™ database) was utilized to understand fluid deliverability by production zone through time and a Petra™ database was used to generate temporal production maps. The fourth study ensured that an integrated look was utilized to review any impact that historical operations may have had on field performance. The fifth study integrated pressures from MDT’s and SBHP through time in order to understand how pressure was changing areally and vertically. Cross sections and areal maps were generated of the analysis that can be utilized for identification of the initial steam flood areas. The final study addressed the water movement in the first Eocene. Significant changes in produced water salinity have historically been attributed to poor casing cementing practices early in the field’s life that lead to dump flooding of the 1st Eocene Reservoir by an overlaying aquifer. In order to confirm this report and to evaluate if dump flooding is still occurring, all aspects of water movement were analyzed. This included an Material Balance study, water cut maps through time, salinity maps through time, analysis of the newly collected water chemistry dataset and a detailed review of the OOWC and the current OWC.

Successful completion of the HARP study occurred on time and all deliverables were transferred to the Full Field Project Team and are currently being utilized to select an optimized location for initial steamflooding. This integrated asset management approach touched all aspects of the project and added significant value in the understanding and forward planning of this reservoir and the possible high CAPEX EOR steamflood project

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