Identifying Reservoir Heterogeneity of the Ratawi Limestone in Umm Gudair Field, Kuwait; Utilizing Seismic Attributes and Post Stack Inversion: A Case Study

摘要

The Umm Gudair field is located in West Kuwait. Oil was discovered in the Lower Cretaceous Minagish Oolite in 1962 and around 180 wells have been drilled on the structure. The field has been geographically divided into three smaller sectors; East Umm Gudair (EUG), West Umm Gudair (WUG) and South Umm Gudair (SUG). It essentially consisits of two anticlines, EUG/SUG and WUG connected by a saddle; into a single accumulation. Overlying the Minagish Oolite is the Ratawi limestone reservoir of around 300 feet, and is composed of mudstone/wackstone rock, representing middle to inner ramp depositional setting. The reservoir is broadly defined by three units; Lower, Middle and Upper units. The Lower and Upper units are non-reservoir, while the Middle unit of an average thickness of around 50 feet, has moderate to high porosity, is hydrocarbon bearing and developed in EUG. Six wells have been tested till date, with relatively low productivity and rapid decline of pressure, suggesting that the unit is heterogeneous. Based on the recently acquired seismic data, an integrated study was conducted, encompassing geological, geophysical and petrophysical data to understand the reservoir complexity. Seismic attributes along with deterministic inversion techniques, utilizing the relationship of acoustic impedance and porosity have been employed to identify areas of good porosity development. The multidisplinary work has provided an understanding of the reservoir heterogeneity and is expected to be used in future development of this reservoir.