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Gas for the Kingdom - Evaluating the Kidan Structures

Gaber, Waleed *1; Sneep, Rik 1; Holstege, Gijs 1; Skaloud, Dieter 1; Al-Nasser, Kadhem 1; Lingo, Mario 1; Al-Khalifa, Mohamed 1
(1) South Rub Al-Khali Company Ltd., Al Khobar, Saudi Arabia.

With a growing demand for gas resources in the Kingdom of Saudi Arabia, the interest in developing the Kidan sour gas accumulation has increased since its discovery in 1967. Significant challenges exist however: the gas is classified as sour with H2S and CO2 concentrations of up to 35% and 10% respectively. The need for special drilling and completion materials and tools as well as heightened HSE requirements in combination with the remote location in the Empty Quarter, make drilling and data acquisition operations challenging. In this presentation we will illustrate how the evaluation of recently acquired data has shed new light on the Kidan giant.

The Kidan North and South structures measure 200 km in length and is up to 50 km in width. The dimensions by themselves pose a significant challenge to the evaluation program with initially only a sparse well coverage. Between 2008 and 2012 SRAK drilled four wells to further explore hydrocarbon contacts, reservoir development, fluid composition and deliverability. Additionally, recently acquired 3D seismic has improved the understanding of the subsurface significantly. Detailed attribute analysis show an intricate fracture pattern, as well as amplitude anomalies, of which the implications on production behavior are currently being studied.

The Upper Jurassic Arab reservoirs are well developed lagoonal dolomites, with a highly porous oolitic limestone shoal present in Kidan North. To investigate the down dip extent of the accumulation with regards to structural spill point and the potential for pressure compartments, a vertical well was drilled downflank, with a dedicated updip sidetrack, targeting the other side of the main N-S faultzone. Preliminary results confirm the assumption that there may be volume upside with different contacts on either side of fault/fracture zones within in the same megastructure.

From here on, reduction of still significant subsurface uncertainties and further drilling in combination with the execution of studies aimed at finding ways to safely and economically handle the sour components are the key elements of future evaluation.

 

AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain