Proppant mixtures

A method for forming a propped, subterranean, hydraulically-fractured field in an oil or gas well by steps that comprise:

• injecting into the fractured field simultaneously with a fracturing step or shortly thereafter a volume of first proppant and a volume of second proppant exhibiting a higher average crush strength relative to said first proppant,
• wherein the first proppant and the second proppant are substantially the same size,
• wherein the first proppant is an uncoated proppant,
• wherein the second proppant is a resin-coated proppant,
• wherein the injecting into the fractured field comprises injecting:
• (i) a mixture of the first and second proppants, wherein the amount of the second proppant is about 10-30% and the amount of the first proppant is about 70-85%;
• or
• (ii) repeatedly and sequentially injecting the first volume of proppants and then injecting the second volume of proppants for at least two cycles of such alternating injections to form a layered structure in the horizontal or vertical direction of first proppants and second proppants within the fractured subterranean field and distant from a wellbore wherein the amount of the second proppant is about 10-30% and the amount of the first proppant is about 70-85%.