The work started on May 26 and this is the fourth project to be drilled, funded by a second round of strategic investment from Fortuna Silver Mines.
Buenavista is a precious metal-bearing, structurally controlled vein system in northwest Durango, 270km northwest of Durango city.
Prospero noted that, as with the first three projects, the programme is preliminary and intended to confirm below surface structures to determine where in the vertical epithermal column an ore zone might lie.
The 3,000-metre drill programme, starting on Buensavista South Stockwork, will test at least four principal drill-ready zones.
As well as the Buenavista South Stockwork, other targets include the Buenavista northeast dike/vein, the Camaleon vein and the Pajaro Stockwork.
Prospero's field crews have just completed channel sampling at the Pajaro zone and a geologist is currently on site to conduct detailed structural mapping and assist in drill hole targeting, the group added.
Prospero noted that between 1996 and 2008, 11 holes were completed at the Buenavista northeast zone testing for relatively shallow mineralization.
Best intersections included 2.37 metres (m) of 400 grams per tonne silver (Ag) and 0.27 g/t (grams per ton) gold over 100m in one hole, and 4.3m of 87 g/t (grams per ton) silver, and 0.08 g/t (grams per ton) gold in another.
In a separate statement on Wednesday, Prospero said it had completed its second and final tranche of a placing, raising in total, around C$1.009mln gross.
For the second tranche, the firm sold over 5.4mln units at C$0.09 each for gross proceeds of around C$492,200
Each unit consisted of one share and one half a share purchase warrant, with each whole warrant entitling the holder to buy a further share for C$0.16 for two years.
As previously stated, the net proceeds will be used for project generative exploration programs in Mexico, adding value to its existing property portfolio and other exploration expenditure.
In Toronto on Wednesday, Prospero shares gained 4.35% to C$0.12 each.