Low fluid loss fracturing composition

Claim 1

A LOW FLUID LOSS ADDITIVE FOR A FRACTURING OIL CONSISTING ESSENTIALLY OF A PRIMARY PLUGGING AGENT FINELY DIVIDED OIL-INSOLUBLE SOLID PARTICLES IN AN AMOUNT FROM 30 TO 70 PERCENT BY WEIGHT OF SAID ADDDITIVE WITH AT LEAST ABOUT 0.20 PERCENT OF SAID PARTICLES HAVING A PARTICLE SIZE LESS THAN ABOUT 10 MICRONS, SAID PARTICLES BEING PHYSICALLY AND CHEMICALLY INERT IN OIUL; AND A SSECONDARY PLUGGING AGENT HAVING SUBSTANTIALLY WATER-INSOLUBLE, SOFT AND PLIABLE STRUCTURE UPON DISPERSION IN OIL CAPABLE OF SEALING INTERSTICES BETWEEN SAID PRIMARY AGENT PARTICLES, SAAID SECONDARY AGENT, IN AN AMOUNT FROM 70 TO 30 PERCENT BY WEIGHT OF SAID ADDITIVE, BEING SELECTED FROM THE GROUP CONSISTING OF MONTAN WAX, ASBESTOS FINES, PLASTIC FINES, CELLULOSE FINES, RUBBER FINES, AND METAL SOAPS OF FATTY ACIDS HAVING AT LEAST 14 CARBON ATOMS, A MAJOR PORTION OF THE METAL OF SAID SOAPS BEING POLYVALENT; AND CONTAINING AN OIL-SOLUBLE DISPERSING AGENT IN AN AMOUNT SUFFICIENT TO DSPERSE SAID PLUGGING AGENTS IN OIL.