Abstract: An aqueous heteropolysaccharide solution is treated to improve its injectivity into a subterranean hydrocarbon reservoir by passing the solution through a colloid mill.

Abstract: A method is disclosed for determining the relative amounts of two fluid phases in a subterranean formation, one phase being mobile and the other being substantially immobile. A sweep fluid which is substantially free of the immobile fluid is injected into the formation by means of a well in an amount such that a measurable first portion of the sweep fluid in the formation adjacent the injection well remains unsaturated with the immobile fluid, and a second portion adjacent the first portion becomes saturated. The sweep fluid is then produced from the formation, preferably by means of the injection well. The concentration of immobile fluid dissolved in the produced sweep fluid is measured as a function of volume produced to determine the volumes of the two sweep fluid portions; these volumes are then used to calculate the relative amounts of the two fluid phases in the formation.

Abstract: A method for determining the relative amounts of two fluid phases in a subterranean formation containing one mobile phase and a substantially immobile phase. A fluid which is substantially free of the immobile phase is injected into the formation by means of a well in an amount such that a portion of the injected fluid in the formation remains unsaturated with the immobile phase. The injected fluid is then preferably produced from the formation by means of the injection well. In another embodiment, the injected fluid is produced from the formation by means of a second well. The concentration of immobile fluid dissolved in the produced fluid is measured to determine the relative amounts of the two fluid phases in the formation.