Morocco Bound - A North African Exploration Success Story

Harker, Stuart D.¹
(1)Circle Oil Plc, Finchampstead, United Kingdom.

Circle Oil began exploration in Morocco in 2006 after signing for an onshore concession in the Rharb Basin. The Rharb Basin has a long history dating back to the first well drilled in 1890 and small oil and gas fields were first discovered based on surface geology, seeps and latterly using 2D seismic. Circle Oil was the first company to acquire a 3D seismic survey in the Rharb Basin over the winter of 2007-2008. The first well of a 6 well programme started in September 2008 in the Sebou / Oulad N’zala concession. The target of this well was determined using seismic amplitude analysis. It was successfully drilled, then tested gas at commercial rates and the well tied into the existing pipeline to the coastal town of Kenitra for local industry use in November 2008. Five additional wells were drilled on different targets through to April 2009. Four more successful gas discoveries were tested and one well with strong indications of gas on logs will be tested as part of the 2010 drilling campaign. Circle signed for two larger nearby concessions of Lalla Mimouna Nord and Sud in January 2010 and 3D seismic surveys and a wells are planned for 2010-11 on the Rharb Basin blocks.

The Rharb Basin is situated midway between Tangier in the north on the Mediterranean coast and the Moroccan capital of Rabat to the south on the Atlantic coast. The basin contains over 3000m of Late Tertiary clastic sediments. A sequence stratigraphic approach was used to subdivide the Late Tertiary “Productive Series” of the basin, with the definition of 8 distinct units. The Mio-Pliocene mudrock depocentre contains thin good reservoir quality gas-bearing sands. The seismic response of the gas sands shows up as bright negative amplitudes on the 3D seismic, as the gas content lowers the density and slows the seismic velocity. Detailed interpretation delineated the location and geometry of the anomalies for drilling targets. The gas sands are contained in combination structural-stratigraphic pinchout traps with both footwall and hanging wall structures present. Co-eval marls and shales provide top, bottom and lateral seals.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.