Sonoro Energy Wins Selat Panjang PSC Tender in the Central Sumatran Basin

Sonoro Energy Ltd (TSXV: SNV) with it local partner PT Menara Global Energi has won the Selat Panjang PSC in the 2019 Conventional Bid Round in Indonesia.

Selat Panjang PSC Block in the Central Sumatran Basin
  • Sonoro has a 25% interest in the project with an option for up to an additional 24%.
  • Menara Global Energi has an initial 75% interest and shall be responsible for the signature bonus and for funding the first year G&G program.  Sonoro interest to be repaid on terms to be agreed.
Tender Bid
  • Signature Bonus: US$5 million
  • G&G Study
  • 2D: 500 line km
  • 3D: 200 km2
  • 6 wells

The 923 km2 Selat Panjang PSC is situated in Riau province, Central Sumatra and is approximately 925 km from Jakarta and 110 km from Pekanbaru (capital city of Riau Province).

In 2015 the Indonesian Ministry of Energy awarded  the Selat Panjang PSC, then totalling 1,316 km2 to Petroselat NC Ltd. part owned by Petrochina International.  The agreed work program included a G&G Study and data compilation, 2D seismic and 1 exploration well.  The PSC was terminated by the Ministry in 2018 and the development program proposed by the previous operator was not implemented.

The previous operator reported that the PSC had produced since 1994 with average annual production of 100,000 barrels with remaining 2P reserves of 7 MMBO.  Petroselat identified 7 leads and prospects on the PSC with reported potential for 320 MMBO and 1.5 Tcf.

The Central Sumatran Basin
North and Central Sumatra Basins and fields. These basins formed in a back-arc environment.

The Central Sumatra Basin along with the North and Southern Sumatra Basins formed as a result of back-arc extension resulting from the subduction of the Indian oceanic plate beneath western Indonesian portion of the Sundaland Plate.  During the Eocene to Early-Oligocene, extension resulted in rifting which generated a series of half-grabens.  These grabens filled with syn-rift nonmarine facies, including fluvial, del­taic, marginal lacustrine sandstones, and shallow to deep-water lacustrine shales.  With the cessation of rifting, thermal relaxation resulted in a sag phase which increased accommodation and saw further deposition and increased thermal maturity of the lacustrine source rocks.  Renewed subduction or more likely a change in subduction rate saw compression in the back-arc environment from the middle Miocene to the Holocence producing many structural traps for conventional hydrocarbon accumulations.

Reservoirs formed in upper Pematang Group (Palaeogene) non-marine sandstones however the principal reservoirs in this system formed in the Early Miocene Sihapas Group marine sandstones.  The Pematang Group was deposited in a series of small en-echelon grabens which have a Lower Red Bed fluvial-alluvial unit, overlain by the Brown Shale lacustrine unit and capped by the Upper Red Bed unit.

The basal transgressive unit of the Sihapas Group, the Menggala Formation consists of well-sorted quartzose to sub-arkosic sandstones which typically constitute more than 50% of the formation.  The Menggala Formation has an average porosity of >20% and an average permeability of 1500 mD.

An abnormally high thermal gradient has resulted in a shallow oil window with the Oligocene Brown Shale of the Pematang Group being the principal petroleum source rock.  The Brown Shale Formation (lacustrine) of the Pematang Group with the Sihapas Group sandstones is one of the most important lacustrine oil systems in SE Asia.  The Pematang reservoirs are generally small and occur with the rift basin.  The giant fields of Minas and Duri with Sihapas reservoirs occur principally along the eastern margins of the rift basins.  Most of the oil-fields are located in drape structures of basement highs along the eastern flanks of the half-grabens up-dip of the Pematang formation source rocks while others are related closure generated by basin bounding faults.  The lack of gas within the fields of the Central Sumatra Basin is notable reflecting the maturity of the Pematang-Sihapas system and the dominance of lacustrine source rock.

25 billion barrels STOIIP has been identified within the Central Sumatra Basin of which 4 billion and 8 billion barrels are in the Duri and Minas fields respectively, making them amongst the largest in SE Asia.

Note: Cmi Capital is a Sonoro Energy shareholder