Cantabrian-Pyrenees Basin

San Leon, through its 100% owned subsidiary Frontera Energy, is in the process of acquiring 4 exploration licenses in Spain, which have been formally awarded.

Spain  Cantabrian Ebro Asset Map

Northern Spain has a long established working petroleum system, dating back to the late 1800’s.  Numerous seeps and shallow, naturally occurring asphalt beds have been identified; with inchoate hydrocarbon production from mining of tar sands and from shallow wells.  In the late 1950’s and early 1960’s, onshore Northern Spain was targeted for oil and gas exploration by many international companies.  The results of this were the discovery of the Ayeluengo oil-field, producing from Jurassic and lower Cretaceous reservoirs; and the Castillo gas-field, producing from the Albian/Cenomanian Flysch deposits.  The Serrablo gas-field, producing from Eocene foreland-basin deposits, and the offshore (Bay of Biscay) Gaviota gas/condensate field were also discovered in the 1970’s.  Although the results of these exploration efforts resulted in meager conventional reserves, these wells proved the potential of several world-class unconventional reservoirs.

Spain Cantabrian Ebro Geology

Fm. Valmaseda (Enara Shale Gas)

Age:                    Albian-Cenomanian (Cretaceous)
Thickness:          2000 m (gross)
Kerogen Type :   Type II / III              
Richness:            TOC av. 1% wt (3.6% wt locally)
Quality:                HI up to 13
Yield potential:            ?

Jurasico Marino

Age:                      Liassic (Jurassic)
Thickness:            max. 600 m, 50 m (black sh.)
Kerogen Type :     Type I / II
Richness:              TOC up to 8.7 wt %
Quality:                  HI up to 760
Yield potential:      S2 up to 56.5 mg/g 

Stephanian coals and bituminous shales  

Age:       Stephanian-Westphalian (Carboniferous)
Thickness:         up to 600 m (gross)
Kerogen Type :  Type II / III
Richness:           TOC up tp 51%
Quality:               HI up to 257
Yield potential:    S2 up to 130.4 mg/g

Carboniferous shales, deposited during the Variscan orogeny, analogous to San Leon’s Carboniferous shale play in Poland, have shown significant shale gas potential.  The Paleozoic section is often more than several thousand meters in thickness, and has shown Type II and Type III kerogen, with coal and high TOC shale within the gas generating window.  Carboniferous shales and coals are known to have sourced the gas in the Gaviota field.

Liassic shales sourcing the Ayeluengo field are reportedly several 100 meters thick, with TOC’s upwards of 8%, and are residing in the hydrocarbon-generating window. Asphalts linked to Jurassic shales have been actively mined in Northern Spain, and are Jurassic oil is also known to have been the reducing agent for Cantabrian lead/zinc deposits in Lower Cretaceous limestones.

The Upper Cretaceous (Albian/Cenomanian) has proven gas reserves in the Castillo field.   The Valmaseda Formation proved in the 1960’s to be a viable exploration target, with vertical wells capable of IP rates of several MMSCFD.  Decline curves were steep, however, suggesting low permeability.  Modern drilling, completion and stimulation techniques promise to allow for sustained high production rates from the Valmaseda Formation, making the Albian/Cenomanian section a highly attractive unconventional target. The latest Viura discovery (2010) put in production in March 2015 with IP rate of 300,000m3/d (10.5MMSCFD) going up to 500,000m3/d (17.5MMSCFD) in the end of the year, proved that Upper Cretaceous play.

Eocene shales deposited in the fore-land of the Pyrenean mountains have proven to be the source rock for the Eocene Serrablo field as well as having sourced the Riudaura discovery. Eocene deposits are flysch deposits, deposited in the fore-land of the Pyrenean mountains. TOC values are 1-1.5%, and the maturity is within the hydrocarbon generating window.

Spain Cantabrian Ebro Licences 1



Spain Cantabrian Ebro Licences 2


Spain Cantabrian Ebro Licences 3


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