Reading and Learning from a Halliburton Frac Treatment Graph 

So I probably won't answer this as good as an actual frac engineer, but I'm guessing there are primarily two reasons. One- a pressure response signaling they could be heading towards a screenout. That would possibly make them conclude the stage early to prevent issues. Thus, stopping sand and attempting to flush the well. Two- if what was planned has been pumped. Remember, they're following a schedule (basically a recipe) from the completions engineer at the E&P company that hired them to frac the well. That engineer has outlined the treatment (and amounts) that should be pumped. Once that target is hit (for example- amount of sand) they will move to the next step- in this case, flush.

Ohh man...that's a huge topic with lots of equations haha. I won't be able to do a video on that...that'd have to be an entire course. Anything specifically that you're looking for?

@@OilfieldBasics No thanks .But all off us looking for new videos on frac treatment .Thanks very much

The ball is seating on the plug that prevents flow into the previous stage. We don't want to pump into the stage that we've already finished. Once the plug is set and before the ball is dropped, the wireline crew perfs the casing (allowing for the flow into the next stage in a few moments once they're out of the hole). Then they drop the ball which then at that point seals the previous stage by seating in the plug. Does that make sense? Easier to draw it out than type it.

@@OilfieldBasics Yes. Thank you for the response.

Can you elaborate a little on what you mean? Are you asking how they decide when to ramp up to the next concentration level, or how to calculate the total sand amount in a job (based off the concentrations)?

Matthew Rangel There are many factors to consider when designing the total proppant mass, the proppant concentrations to use, volume of sub-stages (how much you pump at each concentration, and the max concentration. For the majority of horizontally drilled wells in shale formations you will see roughly 300-750 klbs of proppant with a max concentration from around 2.5 - 5.0 ppg. When it comes to proppant concentrations used within the stage it’s a little more complicated. First, you will normally always start with a very low concentration which will range anywhere from 0.1 - 0.5 ppg. The purpose of pumping these light concentrations is to erode the perforations and near wellbore area so you can make the entry points larger and reduce entry friction. This will enable you to pump at lower treatment pressures and make room for the higher concentrations or larger sieve sizes that are to follow. You could start immediately at higher concentrations, but you are increasing the risk of potentially screening out the well. A near wellbore screen out occurs when enough proppant settles in the near wellbore area and creates a flow restriction great enough that you can no longer pump into the formation at a pressure below your maximum allowable pressure. Getting further into the fracture treatment you will increase the proppant concentration every XX bbls. How much proppant mass you decide to pump per concentration is dependent on what you are trying to accomplish from a fracture design standpoint. Let’s say you have a formation where you expect incredibly complex fractures or want long fracture length. You will want to spread your total proppant mass out over a larger volume of fluid. This will be accomplished by larger sub stages at lower prop concentrations. The proppant is stepped up in concentration and or size towards the end of the treatment because you want higher fracture conductivity in the near wellbore area. Fracture conductivity = fracture width * permeability. Theoretically this area will have to handle the highest flow rates when it comes time to put the well on production so you want the fracture to be wide enough here so it won’t restrict the flow. There is so much more I could talk about here, but this honestly would need a video dedicated to it. I was a senior field engineer at Halliburton and also spent a few years as a senior frac engineer for a consulting firm.