The Australian Renault driver made it out of Q2, but lost control of his car towards the end of the session, clipping the barrier with his rear wing.
The team attempted to complete repairs so that he could run in Q3, but just failed to get him out in time. He thus had to settle for 10th on the grid having not set a time in the final session.
"The cars as we know are quite sensitive," he said. "I had to get through some lapped cars.
"Obviously they're off the race line, but turning in and braking, it depends where the wind is coming from. It felt like as soon as I got in I lost the rear.
"It just kept going and going until I hit the barrier and damaged the rear wing. The team actually got very close to getting me back out on track for Q3. I think one more minute and we were on track.
"I reckon another minute, the car would have been ready to go. But obviously, we ran out of time. So we'll try to make something happen tomorrow."
Ricciardo said his team has lost out on the tricky surface at Portimao due a lack of downforce compared to its main rivals.
"It's been a pretty tricky weekend, it's been probably tricky for everyone," he said. "It's very slippery, this new surface, I don't think it's had that much curing time. So I guess that the oil and whatever is still coming up from it.
"I think for that, everyone's probably just put max downforce on. And we know we've improved there, but it's still I'd say, our main limitation is max load and downforce.
"And I don't think we're able to generate the grip on this low surface that maybe our competitors are, so I think that's where we've missed the tenth or two if I was to make an assumption. Obviously getting into Q3 was our target. We did, but obviously then had some damage with the spin."
Ricciardo conceded that it won't be easy to make progress in the race, with limited passing opportunities.
"I hope the race can provide some entertainment. I'm hoping it'll be like Mugello where we didn't expect it to be good. And it was. Hopefully it can, but obviously Turn One being so fast, you really have to be alongside the car to make it happen.
"Otherwise it is tricky to overtake. Maybe the conditions with a cold track, it might produce some graining, and then you might get some differences in cars and speed, and hopefully that creates opportunity.
"Into Turn Five, it is a hairpin – it is pretty narrow at the apex, but I think if you get a run into Turn Five, it could be an option."