Category Archive: Frac

API Frac Sand Standards and Microproppants

There has been a slowly developing trend in proppants in the oil and gas markets. That trend, the size of the silica sand. The market has demanded a smaller and smaller size of silica sand as the industry has grown and evolved.
The size of the sand used in fracking started with mesh sizes like 16-30, 20-40, 30-50 standard sieve size mesh. Eventually, 40-70 and 70-140 mesh size silica sands became the norm when propping open a well.
At each shift to smaller sized silica, oil and gas wells increased production in both barrels per day and total life of the well.
Does this make sense? Let me ask you another question, that might help understand this trend. Would you rather lie on the tips of three landscaping spikes or bed of thousands of nails? The same reason that a bed of thousands of nails is much preferred over the few spikes, the smaller silica sand grains work better to hold open the cracks in the shale after the fracking process. The smaller silica can distribute weight of the cracks more evenly over each grain of sand. This increases the amount of pressure the silica sand can withstand before crumbling to dust.
The mesh sizes like 70-140 grain size silica can penetrate smaller cracks that happen during the fracking process. This increases the total open surface area of the shale for oil and gas to flow to the well head. The more surface area, the higher production of each well. Halliburton has marketed a product service known as MicroScout which has shown improvements in well production.
Another benefit of using smaller sand is the distance the sand can be carried further away from the well head. This is known as the “Settling Velocity Rate” (“SVR”).  The larger and heavier the sand, the quicker the sand settles in slurry. The smaller sand stays in suspension and can travel further, thus leaving more surface area propped open.
With the understanding of these ideas, the fracking world has started to develop the concept of microproppants. These are particles smaller than a 140 mesh grain. This idea makes sense, but do the normal material testing methods for frac sand work with the smallest of silica?
There will be a series of articles that explain and breakdown each American Petroleum Institute test methods for frac sand. Then compare to see if those tests correlate to smaller grain size silica (also known as microproppants).