an amine an amide a hydroxyl or a thiol group this reaction can be carried out at ambient conditions and also under conditions occurring in a subterranean hydrocarbonaceous formation these gels are novel in that they are unaffected by high saline concentrations often encountered in oil reservoirs high temperatures encountered in said reservoirs do not adversely affect said gels carbonate bicarbonate and sulfate anions encountered in oil reservoirs which are known to affect certain metal crosslinked gels but do not affect these novel gels these novel gels can be formed under all ph conditions and are particularly useful in ph conditions of 10 or less a method for making a kindred gel is discussed in u s pat no 4 157 322 which issued to colegrove on june 5 1979 unlike colegrove the instant gelation reaction is not catalyzed by a salt which is acid generating upon the application of heat this patent is hereby incorporated by reference gels utilized as chemical blocking agents herein can be made from various related materials these materials will be discussed later if the formation is over pressured which means the reservoir pressure is greater than the hydrostatic pressure of water 0 433 psi ft standing in the wellbore the volume of chemical blocking agent should be prepared from the high density brine as is anticipated a relatively small amount usually less than about 50 barrels of the liquefied chemical blocking agent is required to isolate the perforated interval and the washed out portion of the formation surrounding well 4 as shown in fig2 after about 2 to about 4 hours the chemical blocking.