Formation treating methods

Abstract

Disclosed are methods for treating wells to form a permeable barrier around the well for consolidating unconsolidated mineral particles such as sand in a subterranean petroleum formation penetrated by a well, or for forming an impermeable barrier for fluid entry control, or for plugging the well for abandonment. A fluid containing a polymerizable resin such as furfuryl alcohol, a polar organic diluent such as butyl acetate and a mixture of oil soluble acid catalysts including one low pK and one high pK acid to cause polymerization of the resin at formation temperatures is prepared. The preferred low pK acid is toluene sulfonic acid and the preferred high pK acid is oxalic acid. The two acids and total acid concentration are selected to cause the polymerization reaction to be essentially complete in from 0.75 to 4.0 hours and preferably 1.0-2.0 hours at the formation temperature. This fluid is injected into the formation to saturate at least a portion of the formation adjacent to the well. In one embodiment, to form a permeable treated zone for sand control, an aqueous fluid comprising water which is from 70 to 100% saturated with inorganic salts including sodium chloride is injected into the same portion of the formation contacted by the resin containing fluid. The injected resin-containing fluid is allowed to remain in the formations for at least four hours to accomplish at least partial polymerization of the resin, forming a permeable or impermeable mass around the wellbore.