Method for placement of blocking gels or polymers at specific depths of penetration into oil and gas, and water producing formations

A method for re-establishing oil and/or gas production from an underground formation from a well that has experienced water breakthrough, the method comprising:

• injecting a first carrier fluid containing a reactive chemical into the well;
• injecting a spacer fluid into the well;
• injecting a gel or polymer progenitor fluid into the well, wherein the reactive chemical fluid is injected before or after the progenitor fluid and the spacer is injected between the injections of the reactive chemical fluid and progenitor fluid, and
• re-establishing oil and/or gas production from the well, whereby the reactive chemical and the gel or polymer progenitor contact each other and form a filter/sieve in the formation after contact within thirty feet of the well bore to prevent water breakthrough.