|
Description:
|
Understanding the internal organization of the Lower Pleistocene 8 Sand reservoir in the Green Canyon 18 field , Gulf of Mexico , helps to increase knowledge of the geology and the petrophysical properties , and hence contribute to production management in the area . Interpretation of log data from 29 wells , core and production data served to detail as much as possible a geological model destined for a future reservoir simulation .
Core data showed that the main facies resulting from fine -grained turbidity currents is composed of alternating sand and shale layers , whose extension is assumed to be large . They correspond to levee and overbank deposits that are usually associated to channel systems . The high porosity values , coming from unconsolidated sediment , were associated to high horizontal permeability but generally low kv /kh ratio .
The location of channel deposits was not obvious but thickness maps suggested that two main systems , with a northwest -southeast direction , contributed to the 8 Sand formation deposition . These two systems were not active at the same time and one of them was probably eroded by overlying formations . Spatial relationships between them remained unclear . Shingled stacking of the channel deposits resulted from lateral migration of narrow , meandering leveed channels in the mid part of the turbidite system . Then salt tectonics tilted turbidite deposits and led to the actual structure of the reservoir . The sedimentary analysis allowed the discrimination of three facies A , B and E , with given porosity and permeability values , that corresponded to channel , levee and overbank deposits . They were used to populate the reservoir model . Well correlation helped figure out the extension of these facies . |