The making cost of Gel-frac injection fluid can be decreased with use of crude oil instead of kerosene and light oil for base fluid. But in the case of crude oil, the fluid-loss of fracturing fluid becomes so serious as to exceed the allowable value upto 50c.c. in 30min. under 1, 000 psig. So to decrease the fluid-loss some special fluid-loss stopper must be added for practical use. Two factors, which must be hold the fluid-loss stopper, can be counted. The one is fluid-loss decreasing by plugging and the other is dispersing of stopper particles in oil. Here, the study is made for several years on peculiar properties of surface active agents, which are added into the fluid-loss stopper, in order to regulate the two contradictory factors.
In this paper, permeability characteristics of fine-grained rocks to water are investigated in the range of 1 to 8.7atm. and the following results are obtained: 1) clay particles between sands come in to flow as water pressure increases, 2) it takes a longer time for cross flowing to a stratum than parallel flowing to a stratum in test core, 3) the flow of water is laminar flow and subject to Poiseuille's law, and the following experimental relation is found between blow rate (Q0/A) and pressure gradient (Pi-Po/L), (Qo/A)=k(Pi-Po/L)X, where x=1.021-54, 4) mudstones of the Neogene Tertiary have capillary radius in the range of 0.16 to 1.48μ, 5) the flow rate is larger in parrallel flowing to a stratum than cross flowing to a stratum in test core.