Methods of fracturing subterranean zones to produce maximum productivity

Abstract

Methods of fracturing subterranean zones to produce maximum hydrocarbon productivity are provided. The methods are basically comprised of providing a fracturing fluid comprised of water, a gelling agent present in an amount in the range of from about 0.06% to about 0.3% by weight of the water and an inorganic salt for preventing clay swelling present in an amount in the range of from about 0.01% to about 1% by weight of the water. The fracturing fluid is introduced into the subterranean zone at a rate and pressure sufficient to form fractures and the fracturing fluid is recovered from the zone.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to methods of fracturing subterranean zones whereby maximum hydrocarbon productivity therefrom results. 2. Description of the Prior Art[0003] Hydrocarbon producing wells are often stimulated by hydraulic fracturing treatments. In such treatments, a viscous fracturing fluid which also functions as a carrier fluid is pumped into a producing zone to be fractured at a rate and pressure such that one or more fractures are formed in the zone. Proppant particles, e.g., graded sand, for propping the fractures are suspended in at least a portion of the fracturing fluid so that the proppant particles are deposited in the fractures when the fracturing fluid is broken. That is, a viscosity breaker is included in the fracturing fluid whereby the fracturing fluid reverts to a thin fluid which is returned to the surface. The proppant particles deposited in the fractures when the fracturing fluid looses its viscosity function to p...

AI Technical Summary

Benefits of technology

The present invention provides improved methods for fracturing subterranean zones to maximize hydrocarbon production. The methods involve using a fracturing fluid that includes water, a gelling agent, and an inorganic salt to prevent clay swelling. The fracturing fluid is introduced into the subterranean zone at a high rate and pressure to form fractures, and then recovered. The fracturing fluid has low viscosity, resulting in minimal damage to the conductivities of the proppant particle packs. The methods also involve using a cross-linking agent for the gelling agent and a delayed breaker to reduce viscosity. The fracturing fluid can be fresh water or salt water with dissolved salts. The technical effects of the invention include improved hydrocarbon production and reduced damage to the subterranean zone.

Problems solved by technology

The fracturing fluids utilized heretofore have damaged the proppant particle packs formed in the fractures whereby the production of hydrocarbons through the proppant particle packs is less than the maximum possible.

The damage has been the result of gelled fracturing fluid that forms a filter cake on the fracture faces subsequently flowing into the proppant particle packs.

In addition, the fracturing fluids utilized heretofore have included high loadings of viscosity increasing gelling agents.

When the fracturing fluids have been broken, i.e., reduced in viscosity, a significant amount of polymer residue attaches to the proppant particle packs thereby further reducing the produced hydrocarbon conductivity of the packs.