Online Journal for E&P Geoscientists

EL-Gezeery, Taher ^*1; Al-Anezi, Khalaf ²; Hamim, Ahmed ⁴; Sanjay, Kumar ³; Le Maux, Thierry ⁵; De Joussineau, Ghislain ⁶
(1) KOC, Kuwait, Kuwait. (2) KOC, Ahmadi, Kuwait. (3) KOC, Ahmadi, Kuwait. (4) KOC, Ahmadi, Kuwait. (5) KOC, Ahmadi, Kuwait. (6) KOC, Ahmadi, Kuwait.

This paper describes how Discrete Fracture Network (DFN) models for the Mishrif and Rumaila reservoirs were built. It highlights the approach and methodology that was used for understanding the reservoir connectivity and its drive mechanism. Ultimately, based on these findings, a phased development strategy is proposed.

Mishrif and Rumaila are tight, carbonate, oil bearing, layered fractured reservoirs of Cenomanian- Turonian (Upper Cretaceous) age developed over an asymmetrical anticline, dipping from east to west. Three depositional models through time showed the impact of facies on the primary porosity nature.

The horizontal wells showed good production rates followed by a sharp decrease in pressure and production. This has prompted a detailed integrated study to fully understand the recovery mechanism and increase the well productivity.

A conceptual model has been developed for the reservoir connectivity by integrating static and dynamic data. This comprehensive study combines transient well testing and production data with cores, image logs and a fracture-oriented seismic facies analysis in order to characterize and map the fracture networks occurring in the reservoir units. It has resulted in improving the understanding of reservoir connectivity and flow mechanism.

Based on the findings, 3D DFN models were developed. These models include large-scale fracture corridors and 4 sets of diffuse fractures oriented EW, NS NW-SE and NE-SW.

The fracture corridors are modeled as single large-scale fractures crosscutting all of the reservoir units. Their position, orientation and extent are controlled by the results of all the seismic analyses. The diffuse fractures are modeled as bed-bounded fractures with a density controlled by the rock shalyness. The hydraulic properties of fractures were determined through a calibration of the DFN models against the available well test data. The KH of well tests were compared with the KH of the DFN models and the conductivities of fractures in the models were adjusted so that a good match between the observed and modeled KH was obtained. Finally, the calibrated DFN models were upscaled in order to compute full-field equivalent fracture properties usable in dynamic simulations. Two successful horizontal wells were drilled recently via completion of the study, and all the results obtained were integrated in order to improve development strategies and propose better well locations.