It has been found that these additives perform their most desirable functions about equally well in salt water or in fresh water. This has led to the hope that a substantially clay-free aqueous drilling fluid, insensitive to salt content, might be developed using these two ingredients as a base.
Even a combination of these two additives presents many problems of stability of natural asphalt dispersions in water and the provision of good drilling fluid properties. Gilsonite or other asphalts and has viscosity, yield value, gel strength and fluid loss properties within limits considered important in other drilling fluids. Another object is to provide a substantially clay-free aqueous drilling fluid, the properties of which do not change substantially with variations in salt content.
Drilling mud additiveA more specific object is to provide a stabilizing agent which prevents separation of from aqueous suspensions thereof even in the presence of oil. Another specific object is to provide a dry mix which can be added to fresh or salt water together with a stabilizing agent to form a substantially clay-free, low solids drilling fluid with good properties. Still another object is to provide a method of drilling wells through salt, sloughing shale, or both, by use of a drilling fluid stable to both, and which stabilizes the walls of the well drilled through both. Gilsonite is readily available in the oil field for use in well drilling operations. They should be used in the ordinary recommended concentration ranges of from about 0.5 to about 5 pounds per barrel of drilling fluid for the asbestos, and from about 1 to about 20 pounds per barrel for the Gilsonite. Preferred amounts are from about 1 to 3 pounds per barrel and from about 3 to 8 pounds per barrel for the asbestos and natural asphalt, respectively.
Oil base and water based drilling addtiveIt should be noted that due to the lubricating action of the Gilsonite, there is much less need for oil in our drilling fluid than in others, which do not include an asphalt.asphalts derived as residues from petroleum refining and having lower softening points can also be used at lower temperatures. Since gilsonite and the other natural asphalts with higher softening points are effective at both low and high temperatures, however, these natural asphaltic minerals are preferred.
gilsonite can be added separately to water to form the drilling fluid. In order to insure an optimum ratio, however, it is greatly preferred that these three materials be pre-mixed in the desired ratio and then dispersed into the water as a single mixed additive.