N.J.SANDER explains to us the importance of structure drills in the early oil exploration of the Eastern Province, and why this methodology proved to be efficient.
Historical context:
In the five years after the signing of theconcession agreement between Standard Oil of California (now Chevron) and KingAbd al-Aziz Al Saud in May, 1933, field work by Koch, Brown, Steineke, Hooverand Henry had progressed to the point that a generally reliable overview of thesedimentary sequence on the foreland of the Arabian shield was to hand, andprecise details were being added by a group of younger geologists under MaxSteineke, now Chief Geologist.
Regional mapping using reflection seismic methodswas under way, and a gravity survey was planned.
Second order triangulation hadset up a net of accurately located points marked by metal flags set in concreteand that work was ongoing.
Max had as anassistant Dick Bramkamp, a paleontologist with a Ph.D. from UC Berkeley who hadjoined him in 1936. In June 1938, Dammam Well No.7 proved the commerciality ofDammam Dome, and on December 9thor 10thof that yearreinforcements arrived to speed exploration. I was one ofthem.
Before my arrival seven shallow wells had traversed a large portion of the Paleogene to include the upper limit of strata underlyinganhydrite tentatively dated as lower Eocene.
A wildcat, El Alat No.1, had encountered a Paleogene and older sequence much thicker than its outcrop on Dammam Dome where no anhydrite is present. In many localities seismic work had encountered difficulty in obtaining records and interpreting them because the shallow stratum of anhydrite was not continuous.
It had either been leached awayor was replaced by another lithology. These shallow wells had shown that theother rock units of the Paleogene (upper Eocene and Oligocene absent) werepersistent in lithology and fauna over extensive tracts measured in at leasttens of miles.
A question remained: did the attitude of these young strataconform to any degree with that of producing levels ? Obviously, uplift atDammam dome had continued into the Tertiary, but what about the enormous tractswhere salt had not upwelled ? Max had seen and reported some large featureswhere topography and mappable beds suggested the existence of structure, but themappable strata were Miocene or younger laid down unconformably on a MiddleEocene surface, eroded to an unknown extent.
Nestor John SANDER, ”Sandy”, is now eighty-five years old. He is the last geologist living who worked for Aramco before World War II. He wrote the report recommending the Abqaiq structure as the site for a wildcat.
Later he reportedthe reversal of plunge on the En Nala anticline (now Ghawar). After the war, hewas given responsibility for overseeing geology on wildcats. He left in January 1952 to set up a lab in New York. In the leave intervening he stood for a D.Sc.at the Paris University.
Sandy has just finished a book about Ibn Saud.
Wewould recommend you to visit Sandy’s well documented web pagesat:http://home.inreach.com/rotsen/
Nestor J.SANDER
© 2001 Mena Report (www.menareport.com)
