To find it definitively, you'll need to:
1. Consult your vehicle's repair manual: This is the best resource for precise location and diagrams.
2. Use a visual inspection: Look near the oil filter and oil pump area. The sensor is usually a small, cylindrical component with one or two wires connected. It may have a single wire (just a warning light) or two wires (warning light and gauge).
3. Search online for images: Search "2000 Chevy Venture [3.1L or 3.4L engine] low oil pressure sensor location" on Google Images. This can give you a visual reference point.
Important Note: Working on your vehicle's engine requires some mechanical knowledge. If you're not comfortable doing this yourself, it's best to take your vehicle to a qualified mechanic. Incorrectly identifying or working on the sensor could cause further damage.