Replies to This Discussion

Permalink Reply by James CD1 on September 7, 2009 at 15:02

where do the get this sand and/or resin? Who trucks it in and then what happens to all of this
material when they are finished fracking? Just curious.

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Permalink Reply by Mac Davis on September 7, 2009 at 17:19

I believe that most of the sand and other proppant stays down in the gas-bearing shale outside the well bore. That's sort of the whole point of the proppant. It stays down there and keeps the cracks open.

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Permalink Reply by The_Baron on September 8, 2009 at 9:35

Hopefully it stays in the well. If it comes back out under pressure it will ruin equiptment

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Permalink Reply by Tim on September 7, 2009 at 15:18

some of the prop has resin added to it in Wisconsin then it's shipped in by train and loaded onto trucks at various shipping points, what's done with it after frac can be answered by someone that deals with flowback.

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Permalink Reply by The_Baron on September 8, 2009 at 3:37

There are mant forms of sand used. I have seen resin coated sand as well as sand enhanced with some type of ceramic. Thats about all I the knowledge I have on proppants though.

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Permalink Reply by MKarly on September 8, 2009 at 7:06

Frac sand can be used in natural state, some is ceramic and some is resin coated. From what I have heard, the favorite prop is sand that comes out of Wisconsin. Frac sand needs to be a "round" sand to have the desired effects.
Sand usually leaves the sand plants by train, goes to a transload facility then will usually leave by truck to the actual sites.

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Permalink Reply by Mark on September 9, 2009 at 9:24

This discussion is about proppants and I know my proppants so...I will list out all the main types of proppant and some FYI's about them:

* Brown Sand - Polycrystalin Sand, typically contains trace elements other than silica (causing brown color), this is also the cheapest, AKA Brady Sand b/c it came from mines around Brady TX.
* White Sand - Monocrystalin Sand, pure silica grains, AKA Jordan or Ottawa Sand b/c it originally came from the Jordan Sand Formation in mines near Ottawa IL but also comes from the St. Peters Formation and others around the midwest.
* Light Weight Ceramic - Manmade ceramic proppant that is very uniform sieve distrabutions, very round, strong, increasing the conductivity of the proppant pack. Note that the grains are man made and not a coating on a substrait. Think of you kitchen sink but rolled into pellets then fired. Similar weight to sand.
* Intermediate Density - Same qualitys of lightweight ceramic but has a higher allumina content therefore its stronger but ends up heavier.
* Heavyweight Bauxite - High allumina content, Bauxite is the same stuff they refine down into Alluminum. Very Strong but Very heavy. (Most Expensive)

Resin Coated ______ - A resing coating can be applied to any of the above substraits. 2 main reasons for appling them are 1) Encapsalate the fines after a proppant grain has been crushed preventing the fines from migrating & clogging up the pore spaces of the rest of the proppant pack. 2) Bind the proppant pack together to prevent proppant from flowing back into the wellbore.

The biggest thing in selecting the type of proppant required is the amount fracture conductivity needed to produce a given drainage area. In order to determine that, things like closure stress, bottom hole temp, rate the gas is going to be flowing through the proppant pack and the nonDarcy affects from that, the transportability of proppant in the treatment fluid, etc., are all considered.

The Lighter and Smaller the proppant is the easier it is to place in your fracture and transport in a low viscosity fluid. The drawback to lighter is that it means less metal which means its less strong. The drawback to smaller particles is smaller the particles are the harder it is to flow a fluid through them...less conductivity.

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Permalink Reply by Skip Peel - Mineral Consultant on September 9, 2009 at 9:34

Good post, Mark. Thanks. Now that we are well into the drilling phase of the Play, there will be much interest in frac design including proppant. I hope you will stick around and help educate us. I trust your post will bring numerous additional questions. Here's mine: In areas where IP's have been below expectations at least in part due to lower formation permeability, can variations in the completion design particularly as it relates to proppant packs significantly improve production?

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Permalink Reply by Mac Davis on September 9, 2009 at 10:44

By "conductivity," are you referring to the ability of gas to flow through the proppant, not electrical or thermal conductivity?

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Permalink Reply by Mark on September 10, 2009 at 8:55

Skip - With regards to you IP question...In shale gas, IP is largely dependent on the amount of formation you contact with the fracture, for expample, increase the lateral length should result in larger IP, more stages = larger IP, more frac fluids (more rock is being broken/contacted) = larger IP. Those things result in more free gas (reservoir quality dependent) being released into the fracture initially during the fracture process and that is what is being drained. Draining gas from the rock comes in the middle to end of the wells life.
Large pore pressure during IP lowers the closure stress that a proppant sees during that early time (essentually the lower strength proppants perform similer to the high strenth proppants at early time). As time goes on, the pore pressure decreases the closure stress increases. This is were the higher strenth proppants resist crushing/degradation and the sands will crush. Higher strength proppants will have higher conductivity at higher stresses. So, in the middle to end of the life of the well, it takes less energy for the gas to flow through the fracture of a high strenght proppant alowing for the fracture to drain reservoir rock thats further out, ultimatly increasing the EUR. For the civil engineering minded people, think of it as head loss in water pipes, the smoother the pipe with the least amout of twists and turns, the further you can ship the water from the energy created at the water tower.
(not sure if I remotely answered your question or confused you)

Mac - Yes I am refuring to the ability of the fracture to flow oil/gas/water from the reservoir to the well bore through the proppant pack. The equation is:
Fcd= (kf*wf)/(kform*Xf)

Fcd = Dimensionless fracture conductivity
Kf = Permeability of the fracture
Wf = width of the fracture
kform = permiability of the formation
xf = fracture half length

There are also some complicated factors that really need to be considered when designing a fracture but that gets into some serious petroleum engineering that we shouldn't concern ourselves with on the forum, I will get even longer winded than I have been.

Skip, this equation might help with your question as well. Engineers design to optimise the permeability and width of the fracture for what they believe they need and what they can realistically pump.

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Permalink Reply by Skip Peel - Mineral Consultant on September 10, 2009 at 9:30

Good explanation, Mark. Thanks. Many of the members with mineral interests in north Caddo Parish have experienced disappointing IP's from wells where the shale was thick and expectations high. As far as I can tell, the drilling and completion designs were the same as the operators involved had utilized with better results from their wells south of I-20. Many of us are hoping that operators will learn how to modify their drilling and completion designs to address the varying formation characteristics across the Play as it now becomes more evident that the quality of the rock varies from one area to the next. As more step out drilling occurs, some other areas will experience similar circumstances to those that have occurred in north Caddo. We are all hoping for improving prices and completion results. Les B.'s Well Hall of Fame list needs to be much longer.

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Permalink Reply by james a evans jr on March 20, 2010 at 18:01

i am new to this site . i own royalties on a sand mine in erna texas . we have what is being called erna bright sand. compaers to ottowa white. can any one tell me what kind of demand there is for good white frac sand ?

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