Once the toe of the well is perforated and you can inject fluid into the well, pumping wireline perforating guns down the well for the following zones is a much cheaper alternative than abrasive perforating every zone on coiled tubing.

service companies

The plugs are set with fluid pressure and are seated.. the fluid moves into the fractured zones. Sometimes multiple attempts are made to seat a ball (plug). Regardless, well pressure is matched before you open the well head. Hope I understand your question.

all that excess water that has to come out and be removed during the fracking process has to be collected and sent to a Saltwater Disposal Well. Yes, there is some oil and gas inside that watery mixture. When the gas arrives at a SWD facility (either in 18wheeler trucks or via pipeline), the water is collected in large tanks. The water separates from the oil and gas. The oil and gas are collected (called skim oil because they skim it off the top) and sold, while the water is injected deep under the ground through the disposal well. SWD wells typically charge drilling companies $0.40 - $0.50 per barrel of saltwater. It takes around 350,000 barrels of saltwater to frack a well and get it ready for production (depends on the specifics of the well).

Why is the first process used when you will plug and perf the sections above it anyway.

Plug and perf methods are designed with multi stages so when they frack after it they can create effective fractures throughout the whole producing interval. as for the abrasive perforation method with sand slurry, it is used because this perforation creates no casing deformation or debris left in perforation to effect permeability. the velocity from the nozzle creates numerous pathways and channels to natural fractures and allows for a more effective frack after. yes the time it takes to complete the perfs is longer but can be more effective in situations like heavy oil ,thin reservoirs, extremely deviated wells,preventing near wellbore friction, and less tripping in and out of the well.

This abrasive perforator was developed to reduce a coiled tubing trip into the well. With pressurized toe sleeve technology of today it might be a mute point, but when developed, two CT trips were required to start the plug/perf/frac completion operations. 1st trip would be a milling operation with drift diameter mill to cleanup any residual cement, and then a 2nd CT trip with TCP guns to perforate the toe and enable pumpdown of wireline which is a cheaper conveyance mode. This tool enabled the toe to be perforated on the cleanout run to save a CT trip ($25-35k), enabling wireline pumpdown of guns for all remaining zones.

I'm guessing you'd hope it catches on bottom? Maybe plug 1 doesn't have the same lower portion

Milled when it hits the toe/cement?

Or just milled out when the service rig comes to run production and set the pump Jack

+The Man but why do we have oil in the reservoil?

its deposited there

So, that is also why we have gas in the reservgas??

glossary.oilfield.slb.com/en/terms/w/wireline