Doheny, who bats in the top order and can also keep wicket, has been rewarded for his strong form in the Inter-Provincial Twenty20 Trophy. He is the top-scorer in the competition, for North-West Warriors, with 158 runs in four innings at an average of 52.66 and strike rate of 126.40. As for Olphert, he is Warriors' second-highest wicket-taker, with six strikes in four games at an economy rate of 7.66.
Olphert's elevation to the national side is aimed at building a robust fast-bowling pool for the long haul.
"The T20I squad features a familiar core to the squad, but it's pleasing to see a number of new faces earn their call-ups in Stephen Doheny and Conor Olphert," Andrew White, chair of men's selectors, said in a media statement.
"Both Warriors' players have impressed at inter-provincial level this season with consistent performances, while Doheny has also come off the back of a good tour of Namibia with the Ireland Wolves. Olphert has bowled quickly, particularly on good wickets at Comber last month, and his selection gives us an opportunity to look at him as a tactical option given what lies ahead for the rest of the year."
"As always, there are numerous players who could probably consider themselves unlucky not to make these squads but runs and wickets are the currency we look for and the selectors believe we have picked squads that recognise and reward consistent form and performance on the field," White said.
The seam attack will be led by the experienced Barry McCarthy and Josh Little, who recently joined Paul Stirling in becoming a white-ball globetrotter. Little, the left-arm seamer, has had gigs in the T10 league, Lanka Premier League and IPL. His most recent gig was with Chennai Super Kings as a net bowler in IPL 2022, where he trained with the side in Surat before eventually cutting his stint short.
Stirling brings with him big-hitting form from the Vitality Blast, where he hit 200 runs in eight innings at a strike rate of 181.81 for Birmingham Bears. His tally included a career-best 119 off 51 balls, headlined by a 34-run over off Northamptonshire's James Sales.
In the absence of Simi, Andy McBrine is the only frontline spin-bowling option in the 14-man group. Gareth Delany (legspin), George Dockrell (left-arm fingerspin) and Stirling (offspin) can pitch in, if needed.
The two T20s will be held in Malahide on June 26 and 28.
Deivarayan Muthu is a sub-editor at ESPNcricinfo