Fracture Modeling using Outcrop Scale Measurements for Rus Formation (EOCENE), Dammam Dome, Eastern Saudi Arabia

Yassin, Mohamed A.; Hariri, Mustafa
Earth Sciences, KFUPM, Dhahran, Saudi Arabia.

Fractures are commonly responsible for enhancing porosity and permeability within tight carbonate successions and are one of the principal controls on fluid flow in the sub-surface. Use field outcrop studies as analogs for conceptual models are very useful for estimating the fractures network in subsurface. Through this analogs, fractures length and connectivity can be determined, additionally, it can provide information about the permeability anisotropy of the model. This paper is a modeling methodology consists of measuring outcrop fractures properties and calculates fractures intensity which can be populated geo-statistically into 3D grid model. The produce model is used to generate the discrete fracture network (DFN) models based on the fracture scan-line data. Up-scaling the fracture attributes based on the DFN model were used to generate the permeability, porosity and sigma factor to describe the connectivity. The above described method is applied on the Dammam dome, Saudi Arabia. The dome is an oval shape structural body trending NW and covering an area of 150 km2. The area is covered by carbonate rocks. Several researchers have described the geological setting of the Dammam Dome. However, the outcrop fractures characterization and modeling were provided by (Hariri and Abdullatif 2004, Hariri 2006 and Hariri 2011). Fractures in the area are of different types; major and large size fractures mainly related to the emplacement of Dammam dome. Other minor and small size fractures are localized, due to local stresses, and affected by the rock properties (Hariri and Abdullatif, 2004). It has also been indicated that the major large size fractures areas cutting through the whole Rus formation and might e extended to the upper and lower formation (Hariri, 2011). The results obtained through this study are concordant with earlier studies. Moreover, they are further demonstrating how fracture intensity and distribution vary through the Dammam Dome area. They are also compatible with the previously indicated model suggested for fracture distributions with the dome oval shape. In addition the finding of this study demonstrates the possible fractures connectivity model in the area and its affect on the permeability and porosity. Moreover, the output of this study can be extended to characterizes the subsurface fractures and provide a model that represent the spatially variable fractured rock permeability at a regional scale.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012