Thief Zone of Carbonate Reservoirs in the Middle East: Concept, Origin and Identification

Abstract

Huge oil and gas reserve and great production potential exists in carbonate reservoirs in the Middle East. Meanwhile, huge challenge simultaneously exists with the development of those reservoirs. During the water flooding process, many wells can be observed with early water breakthrough along high permeability intervals and further lead to invalid loop of water injection. Those intervals are relatively thin and permeability is ultra-high comparing with those normal reservoirs, and it is called thief zone. The presence of thief zone causes a series of challenge in the development of those reservoirs. From one side, enough water injection is needed to replace the oil in the formation; on the other side, we need to avoid the injected water channel along thief zones from injectors to producers directly. The fundamental step to face this issue is to precisely characterize the spatial distribution of those thief zones, and then propose mitigation plans. To better characterize the thief zone, we need to clarify the concept of thief zone first, deepen the study of its origin, integrate comprehensive information to identify thief zone from wells and characterize it more precisely in the models.