order to change the wettability of the rock from oil wet to water wet when injecting fluids in natural fracture networks most of the fluids will tend to flow in the most conductive fractures this can result in a very poor coverage of the treatment the placement of the treating fluids acid surfactant chemicals for the osmotic membrane inside the fracture network can be rendered more uniform by using u201c diverting u201d agents such as fibers shear thickening or shear gelling fluids and visco elastic fluids suitable chemical species to establish the osmotic barrier around matrix blocks as described above can be found for example in the above referenced u s pat no 6 069 118 which describes osmotic barriers for a different purpose as described in the 39 118 patent the effect of the nature of the chemical species on osmotic pressure is in theory irrelevant in practice the size and electrostatic charge of the particular chemical species will of course affect osmotic flow the list of possible materials that can form a membrane suitable for the present invention is long yet the person skilled in the art of membrane chemistry working in concert with one skilled in the art of reservoir engineering can select suitable candidates for the membrane material by following the general guidance provided in the present specification by following the teachings in the art and by following these specific guidelines the following.