Abstract: This specification discloses a hydraulic fracturing process for forming and propping a vertical fracture in a subterranean formation. This method is particularly applicable for large fracture treatments where fracturing fluids with little or no fluid loss additives are employed to extend long vertical fractures into the formation. It is also particularly applicable for refracturing a formation that has previously been fractured and propped with a proppant pack along the lower portion of the fracture. After a first proppant pack is deposited in the lower portion of the fracture, a slug of fracturing fluid liquid containing fluid loss additives is injected into the formation to deposit the fluid loss additives along the upper surface or leading edge of the proppant pack and thereby provide a seal along this upper edge of the proppant pack.