Reservoir Characterization in Upper Dalan and Kangan Reservoirs, and Its Importance in Field Optimization

Insalaco, Enzo¹, Catherine Javaux¹, Christian Fraisse¹, Claude Legorjus¹, Ole-Petter Hansen¹, Emmanuel Derbez¹, Mohammad Kamali², Ali Moallemi² (1) Total S.A, Pau, France (2) RIPI-NIOC

The Dalan/Kangan Formation is a major reservoir in Iran and the rest of the Middle East Gulf region (Khuff Fm), and contains some of the world’s biggest gas reserves. Geologically the carbonate platform system is complex with fine-scale heterogeneities which impact the static and dynamic reservoir characteristics. These heterogeneities are depositional, strati­graphic and diagenetic in nature and therefore reservoir characterization needs to be an inte­grated multidisciplinary and multiscale approach. The aim is to better understand the facies distributions, sequence stratigraphic architecture and the regional reservoir development, in order to better characterize dynamically the reservoir.

Good fine-scale reservoir characterization is needed in all field optimization projects – and this starts at the appraisal phase of field evaluations, and not just in mature field sce­narios. This necessitates an “anticipation” of the kind of field optimization issues that will be eventually needed. It is also important to think of geological reservoir characterization in dynamic terms at the earliest stage possible, but this must always be underpinned by a strong geological framework. This is achieved by calibration of various dynamic data with the geological understanding, particularly the sedimentological and diagenetic reservoir characterization.

The static reservoir model in Dalan/Kangan reservoirs is highly dependent on the pre­cise type of sedimentary facies, the stratigraphic context and the type of diagenetic over­print, since these control the fine-scale heterogeneity. However, the dynamic reservoir het­erogeneity is particularly sensitive to the diagenetic overprint, and it is seen that the fine scale permeability modeling and 3D permeability architecture is highly diagenetically influ­enced and fundamental to understanding the dynamic behavior of the field. Moreover the understanding of the 3D permeability architecture is important for the application of stimu­lation techniques, such as acidification.