Ceramic proppant selection indicators - density, strength, roundness

Chinese  Ceramic proppant  industry 80 years from the last century began to develop, develop and produce a jet of high-strength bauxite proppant, 1987 in Jiangsu Province successfully developed low-density proppant, have since developed a medium-density, high-density different performance  Proppant   is widely used in the production of oil and gas.
In this proposal in the oil and gas well drilling, oil and gas services and oil additives trade customers choose ceramic proppant, you should consider the following factors to choose.

First, uniform particle size, density. General, proppants used in  hydraulic fracturing  is not a single particle size, but there is a certain range of variation, and if sorting proppant poor level, the process of reproduction, plug flow channel, affecting sand filling fracture conductivity, so the proppant particle size and sorting is a certain degree requirements. Commonly used in the domestic mine 20/40 mesh proppant for example, at least 90% of the sand through the sieve after 20 ~ 40 mesh in between, at the same time requires a screen size greater than the first weight is less than 0.1% of the sand, and less than the last The amount of a sieve is not greater than 1%. Ideal density proppant requirements, preferably less than 2000kg/m3, in order to carry sand-carrying fluid to fractures.

Secondly, strength, crushing rate is small. Proppant strength is an important indicator of its performance. Since the composition and production of proppant production methods, the intensity differences are large, such as quartz sand strength 21.035Mpa, ceramic's strength up 105.0MPa to cracks. After the hydraulic fracturing, fracture closure pressure acting on the proppant fractures, when the proppant strength ratio seam wall formation rock strength is large, there may be embedded proppant stratum; when sewing wall formation rock strength ratio proppant strength, and the closing pressure is greater than the strength of the proppant, the proppant is easily crushed.

Both conditions can cause fracture closure or low permeability. So in order to ensure intrinsic fracture conductivity broken filling, closing at different pressures, to a variety of mesh strength proppants have certain requirements and breakage. Again, high roundness and sphericity. Proppant particle circularity indicates the relative sharpness of the edges, sphericity is similar to the degree of the spherical granules. Roundness and sphericity visual method used to determine, generally 10 to 20 times or under a microscope photomicrograph technique using pictures and then with a standard round, sphericity illustrated contrast, determine round sand, sphericity. With a round ball proppant is not good, its poor penetration of sand filling cracks and corners easily broken, crushed into small particles clog the pores, reducing its permeability. Impurity content Finally, the proppant in the fracture conductivity impurities are harmful. Natural  Frac sand  impurities, mainly carbonates, feldspar, iron oxides and clay minerals. Generally washed with water, acid (hydrochloric acid soil) to eliminate impurities, treated quartz sand will increase the strength and conductivity.