Zion Oil & Gas Inc (ZNOG)

[bdahl385]

The simple answer is "no", you would not simultaneouly produce gas and oil from "different" formations within the same well. This term is called commingling. This is usually undesired because the different reservoirs have different geophysical characteristics and pressures. You don't want high pressure gas to choke off your oil flow for example.

The advanced answer is that it can be done but the completion is fairly complex and expensive. You must have oversized casing in the hole to allow multiple strings of tubing. Each set of tubing would flow gas or oil from a different formation through isolation production packers set downhole to separate the zones from each other. The flow at the surface is then routed to the appropriate topside equipment to deal with the hydrocarbons being produced.

In reality, many downhole reservoir formations simultaneously produce gas, oil and saltwater. All flows to the surface and then topside equipment separates these out individually where the hydrocarbons are sold off and the salt water is re-injected into an underground separate formation (salt water disposal). The key here is that this all flows from the same reservoir, you are not commingling production from separate formations geologically isolated from each other.

If your well has multiple hydrocarbon formations in it separated vertically, you generally produce the deepest formation first. When it depletes or becomes uneconomical, you plug off this lower zone with a bridge plug, dump some cement on it and then move up hole and perforate your next zone. Repeat the process as needed until you run out of zones to test / produce.