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

The South Rub ‘al Khali Company Ltd is an Incorporated Joint Venture between Shell Saudi Ventures<br>Limited (50%) and Saudi Arabian Oil Company (50%) and was set up in order to explore for nonassociated<br>gas in the South Rub ‘al Khali Basin as part of the Natural Gas Initiative in the Kingdom of Saudi Arabia.<br>SRAK’s Unayzah Stratigraphic Play exploration has resulted in the identification, de-risking and drilling<br>of a number of stratigraphic traps in the South Rub Al-Khali Basin. Such traps rely on Nuayyim<br>Formation (Unayzah A Reservoir Unit) and Jawb Member (Unayzah B Reservoir Unit) targets that<br>developed preferentially off-structure. Exploration for these stratigraphic traps is generally difficult as<br>even good quality 3D seismic data cannot resolve subtle facies changes and faults that may be<br>fundamental trapping components. On 2D seismic, such problems are enhanced and exploration<br>therefore relies much more heavily on good geological models coupled with geophysical or geochemical<br>direct hydrocarbon indicators (DHI’s). SRAK tested the largest known stratigraphic trap in its acreage<br>with its sixth well. Critical to the evaluation and de-risking were a sound geological model from<br>analogues in the Saudi Aramco Reserved Area, an up-dip calibration well and a world class, 600 km<br>low frequency seismic (LF) dataset to de-risk the trap.<br>The presentation will discuss the lessons from the current drilling campaign including an update to the<br>geological model for the Unayzah Group for the southern Rub ‘al Khali Basin. The application of low<br>frequency seismic techniques to de-risking has been tested by the drill-bit for both conventional and<br>unconventional traps and this new technology will be discussed.