Operator Schuepbach Energy International LLC (SEI) finalised the drilling contract with New Force Energy Services Inc. in December 2016 with the rig mobilised to site in May with Cerro Padilla-1 spudding in early June 2017.
After the setting of surface casing and installing the BOP operational approvals were received from the relevant authorities for drilling by mid-August 2017.
On 28 August with only 10m of basalt remaining and 3-5 days of drilling ahead before setting casing, the drill string parted and drilling was again temporarily suspended. Initial fishing operations were partially successful with additional equipment ordered from the US to complete fishing operations. These delays in the field incurred rig rates at stand-down, standby or full drilling rates along with operational and general overhead leading to further funds being required.
A number of these challenges could have and should have been better managed by the project Operator, and it was decided to undertake an independent review of drilling operations and management processes. This was undertaken by international experts New Tech Global Ventures (NTG), headquartered in Houston, who then went on to manage the successful fishing operation. Soon after NTG were retained by the Operator to manage all onsite operations.
With management changes made operations recommenced and the Cerro Padilla-1 well was successfully drilled to a Total depth (TD) of 845m and became the first well onshore Uruguay to discover hydrocarbons by identifying a 2m oil saturated Permian sand. The well was successfully completed with production testing recovering a small amount of oil to surface.
Project risk is now much better understood having gone through these processes, and notwithstanding the early success in the first well, the overall objectives of the drilling programme remain largely unchanged as follows:
confirm source rock maturity, quality and extent
confirm conventional reservoir quality and extent - Darcy permeability (>1000md) already measured in core samples 30km apart
confirm migration and potential trap integrity - while not the primary objective 3 of the 4 wells are also targeting structures for oil and gas trapped in either the same sequence or up-dip of oil shows and/or weeping core samples
confirm validity of AVO anomalies identified on seismic
Well #1 - Cerro Padilla-1
This well was designed to confirm the reservoir potential of the Tres Islas sand and Permian source rock at shallow depth.
Drill on same fault block but up dip of Cerro Padilla E-1 corehole which encountered 3m of Tres Islas sandstone with flowing fluorescence to confirm potential oil charge
Permian source rock quality
Permian Tres Islas OOIP P90 = 21MMB
The well was successfully drilled to a Total Depth (TD) of 845m and encountered significant oil shows with logging confirming 2m of oil saturated sand at 793m.
Although only a modest discovery in its own right, as the first ever of hydrocarbons in Uruguay, and the first well of a 4 well programme, it represented a quantum first step in redefining the oil, and potentially gas, prospectivity of the Notre Basin going forward.
New Force rig at Cerro Padilla-1
Preparations for production testing
Figure 1 Cerro Padilla-1 well general schematic cross section
Well #2 - Cerro de Chaga-1 well (Panizza-1)
The Cerro de Chaga-1 well (TD 1,450m), in the Salto permit, is not only situated over a very large structure with considerable oil and gas potential across multiple zones, but also has an extensive and very thick, Devonian or older section beneath what could be a very thick sealing source rock.
The objective of the conventional Cerro de Chaga-1 well is to:
Test largest regional high with 4-way dip closure
Confirm extent, quality and maturity of Devonian source and reservoir rock
Test quality and maturity of secondary Permian source rock - Mangrullo Shale
Confirm existence of deeper sedimentary sequence
At present the well is currently suspended after encountering hole stability issues when a fault was intersected at the base of the basalt. While the faulted zone was successfully cemented it was decided at the time to temporarily suspend operations to allow for necessary repairs and to undertake a review of operations and strategy.
Disappointingly on the back of very good progress drilling the basalt before encountering the fault, and successful recovery of oil at Cerro Padilla-1, this well remains suspended, but it does highlight the challenges of drilling in a frontier basin.
Figure 2 Cerro de Chaga-1 well (Panizza-1) general schematic cross section
Shallow AVO - 1 Well
This well will test a shallow AVO prospect which has been identified by several seismic lines. AVO’s significantly de-risk exploration and can become a very successful exploration tool when calibrated for local geology.
Test shallow AVO prospect identified by several seismic lines
Confirm and refine thermal maturity model
Establish potential of additional targets
NSAI certified P50 prospective resource of 240bc
AVO is favourably:
coincident with sandstone unit
Beneath potential shale/seal
Between potential sealing faults
Achar E - 2 well
This well is a very low cost opportunity to confirm oil migration and test/calibrate the magnetotelluric data set.
Cordobes shale quality and development
Testing oil migration in highly (+1000md) permeable sands up dip of Achar E-1 corehole