... and gas wells exploration. This products used in the construction of deep well fracturing, be filled to the low permeability of the rock deposits in the ... maintain the high conductivity of oil and gas, not only can increase the oil and gas production output, also can extend the oil and gas wellss ... specifications are :12-18 mesh ,12-20 mesh ,16-20 mesh ,16-30 mesh, 20-40 mesh between 30-50 mesh, 40 ...