Fluvial Reservoir Architecture and Cyclic Depositional System: From Example of Improvements in the Reservoir Description to Optimize Production in the Middle Magdalena Valley Basin, Colombia

Peralta-Vargas, Juan¹
 Carrillo, Gonzalo¹
 Gambaretto, Walter¹
 Rodriguez, Corina¹
 Suter, Andreas¹
 Martinez-Uribe, Liliana¹
 Valbuena, Oscar²
 Dederle, Monica²

Casabe Oil Field is a good example of optimizing and increasing production, after the improvement in reservoir characterization based on the state of the art of technology regarding to data acquisition and interpretation. Paper purpose is to shear this experience in

Casabe oil Field, is a mature field discovered in 1941, located in the Middle Magdalena Valley Basin (MMVB); a poli-history and asymmetric basin with later compressional event associated to Eastern Cordillera uplift. The tertiary oil bearing reservoirs were deposited by a fluvial system with large depositional cyclic events during Oligocene-Early Miocene, Mugrosa and Colorado Fms., which overlying unconformable the Cretaceous-Paleogene deposits; and underlying Real Group, a molasses sequence associated to Eastern Cordillera uplift.

The field is composed by 6 to 60 feet thick sand multilayer reservoirs and mudstone forming a succession of 2800 ft thick. Structure is an anticline, 8 km long, cut by a high angle normal fault that conform the western boundary of the accumulation, minor normal faults, perpendicular to the main fault creates 9 blocks. This is a constrain to optimize production and waterflooding, therefore secondary faults have to be accurate placed using both, seismic and well information.

Facies associations were extracted from core data and logs interpretation to establish rock types, and extended to 550 wells. Object modeling was applied to conditioning facies population, in this way, a total of 13 facies were identified along the sequence in around 2000 ft of cores, and three facies association were established to characterize the reservoir architecture.

Utilizing the latest log data acquisition technology, as well as new generation tools, allowed to incorporate some body sands as producer; that according to the characteristic and response of conventional log data, were not interpreted as oil sand producer and therefore ignored for completion. This finding helped as well to increase the reserves estimation of the field.

Reservoir description and data integration is essential to increase production in mature oil field as Casabe. It has been proved that it is required high volumes of water injection, and reservoir architecture understanding to optimize the waterflooding and locate producer wells properly to get the maximum sweep efficiency in the injection patterns.

Results obtained are an incremental production of 160% from 2004 to 2009.