--> ABSTRACT: Glacial Sedimentological Interpretation from Microresistivity Images, Al Khlata Formation, Oman, by Wang, Da Li; Helmy, Mohammed; Rawnsley, Keith; #90135 (2011)
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Glacial Sedimentological Previous HitInterpretationNext Hit from Microresistivity Images, Al Khlata Formation, Oman

Wang, Da Li 1; Helmy, Mohammed 2; Rawnsley, Keith 2
(1)Schlumberger, Al-Khobar, Saudi Arabia. (2) Petroleum Development Oman, Muscat, Oman.

High-resolution borehole microresistivity image data for 14 vertical wells was used for glacial sedimentological Previous HitinterpretationNext Hit in a field in Oman. The sedimentological Previous HitinterpretationNext Hit was based mainly on the identification on borehole images of the characteristics of glacial depositional environments. The characteristics involve sedimentary lithotypes and deformation sedimentary structures, such as diamictites, cross-bedded pebbly sandstones, sandstone breccias, dm-scale faults, sandstone steep beddings, and slump structures. Diamictite deposition is associated with the glaciolacustrine depositional environment, and cross-bedded pebbly sandstones correspond to glaciofluvial depositional processes. The breccias, faults, steep beddings, and slump structures indicate ice-contact glacial depositional processes, which were caused by collapse of supporting ice when buried ice melts away. These glacial-specific characteristics are easily recognized on the borehole microresistivity images that provide continuous records of sedimentary features along well trajectories. However, it is difficult to recognize these glacial specific characteristics on the conventional openhole logs and in poor-resolution seismic.

The 14 wells cover an area of about 400 km², and the minimum extent of space between two of the 14 wells is about 2.4 km. The main challenge to the sedimentological Previous HitinterpretationNext Hit in this field was that the glacial deposition caused extremely rapid vertical and lateral variability of lithofacies and completely unpredictable geology, particularly owing to the poor seismic resolution of the field and limited available core data. There was only an 18-m-thick core acquired in this field. Hence, one had to concentrate mostly on the 14-well borehole microresistivity image data for the sedimentological Previous HitinterpretationNext Hit.

The paper highlights the glacial sedimentological Previous HitinterpretationNext Hit of the 14 wells and demonstrates how to set up a conceptual sedimentological model for further developing a 3D facies model. The case study in this paper improved our understanding of the glacial sedimentological properties and reservoir characteristics of the field, and it also provided a new approach to maximize the usage of borehole image data to perform sedimentological Previous HitinterpretationTop in glacial depositional formations.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.