Chemical Disaggregation of Rock Containing Clay Minerals.
U S Pat 3 508 613 1970 Apr; :
Petroleum-reservoir rock penetrated by a well bore is treated with a disaggregating and fracturing compound to increase the deliverability of fluids from the formation to the well bore. Rocks containing clay minerals that do not swell in water are chemically fractured by treating with a compound, e.g., hydrazine, urea, or an alkali metal salt of a low carboxylic acid. Thus, Berea sandstone cemented by calcite and siderite was immersed in hydrazine hydrate and disaggregation occurred. A second sample of Berea sandstone was immersed in a concentrated aqueous solution of potassium acetate. Disaggregation occurred. A very intense peak at 14.01 Angstroms was observed when the sample was analyzed by x-ray diffraction. Disaggregation was caused by kaolinite expansion.
U.S. Pat. 3,508,613; Apr. 28, 1970; Chem. Abstr. 73:10,796R