I started this series last week with the first step in the fracing process. It all begins in the office, where a team of geologists and engineers closely examine a log that's obtained after the well has been drilled. They work together to identify intervals within the wellbore that they believe to be hydrocarbon productive. This is where they'll set the perforations so the well can be fraced. Once these locations have been identified and their design is finalized, the frac job can begin.
For Henry Resources, a typical frac job lasts two days and begins with the frac crew setting up the equipment on location. Once everything is rigged up, tested, and ready to go, it's time to turn the engineers' red ink marks on the log into actual perforations.
They begin with the first stage which is the deepest in the well, and in this case, around 11,000 feet underground.
"There's 40 explosive devices individually placed inside that steel container and then that fire shoots through the steel container into the casing and out into the formation," says George Miles, Henry Resources frac specialist.
Next, it's time to stimulate or "frac" stage one. But before the hydraulic fracturing process can begin, the crew concocts the perfect cocktail using a small amount of chemicals, a defined volume of water, and a very specific type of sand, which varies according to the depth of the stage.
"We pump the water from over there (frac pit near location) into the tanks on location," says Miles.
Water is then pulled out of the tanks into a hydration unit where it's mixed with gel. After that, the gelled water is mixed with some chemicals and sand in the blender.
"That truck (the blender) pushes the mixture into the high pressure units (also known as the pump trucks).The high pressure units then pump it down the well," says Miles. And by high pressure, he means 30 barrels a minute. That's 1,260 gallons every 60 seconds.
The speed, resultant pressure and gel-like formula help to fracture the formation, propagate the fracture away from the wellbore and connect any natural fractures that may exist.
The next task is keeping the fractures open.
"What you got going on here is the sand-laden phase where we start introducing the proppant into the fluid that's going down the hole and what that does is help propagate the formation. Helps it stay propped open after we stimulate the well," says Adam Munoz, Pro-Petro District Technical Mgr.
In the end, "the gel will break from the sand (and) return to a water phase. The sand will stay in place and allow that porosity to increase from the wellbore all the way out to the tip of the frac," says Miles.
This allows the oil, gas, and water to flow freely to the wellbore where it can be pumped to the surface.
Keep in mind, all of that is only stage one.
At this point, a bridge plug is set between the zone that is now complete and the entire process repeats itself until each stage is fraced. For Henry Resources, it's usually anywhere from nine to eleven stages.
When all the zones are complete, the frac crew rigs down and leaves and a pulling unit is brought in. It's main purpose is to drill out all of the bridge plugs that were used during the frac and install the tubing, rods, and pump needed for production.
After this, a flow line is used to connect the well-head to the appropriate tank battery so the oil, gas, and water can be separated, stored, and eventually sold or disposed.
And with that, production can finally begin.
We'll continue this special series next Friday by addressing some of the hotter topics associated with hydraulic fracturing. For example, a lot of concerns have been raised over the chemicals that are used, and some even say they fear their water supply is being contaminated. We'll talk through all of these issues and more and kill a lot of rumors next Thursday at 10pm on Big 2 News.
To view Part 1, click on link - http://permianbasin360.com/fulltext/?nxd_id=142917