In the drilling process, the balance of the rocks composing the walls of the wells is disturbed. The stability of the walls depends on the original strength characteristics of rocks and their changes under the influence of various factors. Therefore, drilling mud plays large role.
It is known that the main role in the intensification of the process of softening clays is determined by original humidity, and the saturation of drilling mud filtrate under the action of the formation overburden. The absorption of the filtrate of drilling mud occurs not so much under the influence of pressure drop in the system well-reservoir, as a result of physical and chemical effects, growing in most clay rock. The most optimal from the point of view of stability of the borehole walls are cases where in the system the well-reservoir osmotic equilibrium is established, or osmosis is directed from the reservoir into the well.
The greatest influence of the osmotic pressure exhibited when saline drilling fluids are used. This paper examines the effect of polymer salt of drilling fluids clay swelling, i.e. inhibiting the ability of drilling mud.