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Characteristics of Entrapment in the Khuff Formation Around the Arabian Platform: Deposition, Diagenesis, Structure, and Fracturing

CHARARA, M., Schlumberger, Dubai, United Arab Emirates, G. LOUTFI, Abu Dhabi National Oil Company, Abu Dhabi, United Arab Emirates, and R. NURMI,* Schlumberger, Dubai, United Arab Emirates

Most giant Khuff discoveries have been gas; however, recent wells demonstrate that the Khuff can contain oil at shallow depths, whereas deepest wells reveal the destruction of methane and the occurrence of nonhydrocarbon gases. The geological characteristics of the Khuff Formation, which determine hydrocarbon entrapment in economic quantities, range from initial depositional facies to late stage fracturing that is influenced by the varying rock character of Khuff diagenetic zones. Exploration evaluation is difficult because porous zones are not uniformly distributed and a dry test does not necessarily condemn an entire structure.

Careful integration of log and core petrophysical data on key wells with extensive cored intervals allowed construction of formation evaluation models which were tested and then used to interpret intervals and/or wells and diagenetic pore types using well log data. The validity of this approach was confirmed by comparisons with thin sections for cored wells. The detection and distinction of connected and nonconnected oomoldic limestone and dolostones was critical as oomoldic pore types often are the dominant pores of many of the more porous zones.

The most challenging parameter used routinely for evaluating was the fracture character of low porosity zones, including the geologic parameters affecting fracturing. Fracture intensity correlates highly with rock type, lithology, and porosity. Moreover, a multidisciplinary team provided insight into the reservoir characteristics and distribution of fractures which none of the disciplines alone could adequately define.


AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)