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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Where Is My Sand Wedge? Part 2: Lessons from Srak’s First Stratigraphic Trap Test in the South Rub' Al Khali Basin

Geoff Pike1; Craig Harvey1; Michael Hulver1; Ashraf Khalil1; Pieter van Mastrigt1

(1) South Rub Al Khali Company Ltd, Al-Khobar, Saudi Arabia.

The South Rub ‘al Khali Company Ltd is an Incorporated Joint Venture between Shell Saudi Ventures Limited (50%) and Saudi Arabian Oil Company (50%) and was set up in order to explore for non-associated gas in the South Rub ‘al Khali Basin as part of the Natural Gas Initiative in the Kingdom of Saudi Arabia.

SRAK’s Unayzah Stratigraphic Play exploration has resulted in the identification, de-risking and drilling of a number of stratigraphic traps in the South Rub Al-Khali Basin. Such traps rely on Nuayyim Formation (Unayzah A Reservoir Unit) and Jawb Member (Unayzah B Reservoir Unit) targets that developed preferentially off-structure. Exploration for these stratigraphic traps is generally difficult as even good quality 3D seismic data cannot resolve subtle facies changes and faults that may be fundamental trapping components. On 2D seismic, such problems are enhanced and exploration therefore relies much more heavily on good geological models coupled with geophysical or geochemical direct hydrocarbon indicators (DHI’s). SRAK tested the largest known stratigraphic trap in its acreage with its sixth well. Critical to the evaluation and de-risking were a sound geological model from analogues in the Saudi Aramco Reserved Area, an up-dip calibration well and a world class, 600 km low frequency seismic (LF) dataset to de-risk the trap.

The presentation will discuss the lessons from the current drilling campaign including an update to the geological model for the Unayzah Group for the southern Rub ‘al Khali Basin. The application of low frequency seismic techniques to de-risking has been tested by the drill-bit for both conventional and unconventional traps and this new technology will be discussed.