Simple chemical reactions are described which bring about modification of the components of a bitumen. This i!: accomplished by using an oxygen-containing gas and subsequent treatment with alkali solutions of sulphites and/or bisulphites. The resulting water-soluble sulphonated bituminous derivatives have significant emulsifying and dispersing powers and are likely to be of use in extracting the bitumen in situ.
In many locations throu~oui the world there are large deposits of tar sand'. Of particular interest to the authors is the formation located in the Athabasca region of the province of Alberta. This sand, in general terms, consists of unconsolidated quartz grains in which the interstitial spaces are filled with water, clay, and bitumen.
The bitumen present in the Athabasca tar sand is a viscous material with a specific gravity of approximately 1.03 and a viscosity at reservoir temperature, i.e. about 5--8OC, of several thousand centipoises?.
The deposit covers many square miles and in some places the tar sand is practically on the surface; however, it is generally located under an overburden ranging in thickness from a few feet to 200 or more feet% in depth whilst the bitumen content varies between 8 and 20% by weight. The bitumen itself does not generally command a very high price, particularly in the crude state; its separation and recovery must involve a minimum of expenditure in order to be economically attractive for commercial practice. If conventional mining forms one of the primary steps in the process for recovering oil from tar sand, it is desirable to find locations where the overburden is light, i.e. up to 80 ft, and where the bituminous sand is relatively thick, i.e. about 150 ft. In regions where the overburden is in excess of 150 ft, the conventional strip mining method is imprarticable, and irr situ methods have to be developed to reduce the costs. Such reserves are being depleted at a si~~cant rate using a mining technique, and this, by increasing the need for methods that can operate at still greater depths, is a principal reason behind the present investigations.
Various methods have been attempted and proposed for the in situ extraction and recovery of oil and bitumen from formations such as the Athabasca tar sand. However, almost all of them have been found to be either ineffective in actual field operations, or to require the use of significant amounts of relatively expensive chemicals.
For example, one method' proposed a process which involved fracturing the tar-sand formation between at least two spaced wells drilled into it, and passing steam and a dilute aqueous alkaline solution through the tar-sand formation in order -* Contribution No.592 from the Research Council of Alberta