A&D marketing for the oil and gas industry



Onshore Exploration

Envoi has been commissioned by London-listed Gulfsands Petroleum Plc (“Gulfsands”) to assist in its search for a partner to join in the exploration of its two 100% owned and operated blocks, PUT14 and LLA50, situated in the proven producing Putumayo and Llanos Basins respectively, onshore Colombia.

Block PUT14 is located in an under-explored south-eastern part of the Putumayo Basin in southern Colombia, adjacent to the Ecuadorian border. Gulfsands has identified several large stratigraphic basin edge pinch-out leads, together with associated fault closed structures, which lie updip from the prolific Andean foreland play trend where elongate fault closed structures have been the focus of most successful exploration to date. The existing sparse 2D seismic grid over the PUT 14 block clearly shows the pinch-out potential of the proven plays that thin onto the basin margin but can still be sourced by the proven source kitchen to the west. Significantly, the underexplored Putumayo play trend in PUT14 area is an extension of, and lies on strike with, foreland basin margin analogue fields in Ecuador’s Oriente Basin to the south. The primary targets are Cretaceous age Villeta Formation sandstone reservoirs in both faulted and potentially large stratigraphic closures. These clearly show progressive pinch out as the play formations thin eastwards, sourced by mature source rocks in the Caballos and Villeta Formations to the west. Gulfsands is planning a minimum 100 km infill 2D seismic programme which will more accurately define the closures mapped on the existing data and upgrade the leads to drillable status. Subsequent exploration drilling would fulfil all the work obligations of the Phase I initial exploration term for PUT14. The combined gross cost of the planned infill 2D seismic survey and one subsequent exploration well is currently estimated to cost US$ 16 million.

Following the discovery of an Indigenous Community within the block during the course of the initial Phase I exploration term, the PUT-14 contract has recently been reset into ‘Phase 0’ to allow a period of ‘Consulta Previa’ with the community to take place. Following this, the contract will then move back into a renewed Phase I Exploration Term for 3 years such that the earliest this will then likely expire is 2021.

Block LLA50 is situated on the eastern margin of the largest sedimentary basin in Colombia, the 200,000 km2 Llanos Basin, which evolved in front of the Eastern Cordillera uplift of the Andes. The existing, albeit sparse, 2D data acquired in the 1980s over Block LL50 has enabled Gulfsands to define large prospectivity and several fault associated leads up-dip from the much more explored proven-producing central foreland basin play trends to the southwest which contain numerous very large fields. The eastern extension of the Llanos foreland margin play has already been confirmed by fields on strike to the south. The shallow faulted leads defined by Gulfsands to date are interpreted as exhibiting similar traps and drapes of Paleogene Carbonera sands. Stratigraphic potential has also been identified as the stacked fluvio-deltaic sands pinch-out eastwards. Similar to PUT14, the planned 160 km 2D infill seismic programme will refine the leads and allow drillable locations to be defined. One exploration well would then fulfil the work obligations for the current exploration term which is due to expire in May 2018. The combined gross cost of infill 2D and one well is currently estimated to be US$ 15.3 million.

Gulfsands is offering a material interest in one or both blocks in return for funding the forward work programmes in each.