Abstract: A method of optically determining a change in magnitude of at least one dimensional characteristic of a sample in response to a selected chamber environment. A magnitude of at least one dimension of the at least one sample may be optically determined subsequent to altering the at least one environmental condition within the chamber. A maximum change in dimension of the at least one sample may be predicted. A dimensional measurement apparatus for indicating a change in at least one dimension of at least one sample. The dimensional measurement apparatus may include a housing with a chamber configured for accommodating pressure changes and an optical perception device for measuring a dimension of at least one sample disposed in the chamber. Methods of simulating injection of a gas into a subterranean formation, injecting gas into a subterranean formation, and producing methane from a coal bed are also disclosed.

Abstract: A method of optically determining a change in magnitude of at least one dimensional characteristic of a sample in response to a selected chamber environment. A magnitude of at least one dimension of the at least one sample may be optically determined subsequent to altering the at least one environmental condition within the chamber. A maximum change in dimension of the at least one sample may be predicted. A dimensional measurement apparatus for indicating a change in at least one dimension of at least one sample. The dimensional measurement apparatus may include a housing with a chamber configured for accommodating pressure changes and an optical perception device for measuring a dimension of at least one sample disposed in the chamber. Methods of simulating injection of a gas into a subterranean formation, injecting gas into a subterranean formation, and producing methane from a coal bed are also disclosed.

Abstract: An apparatus and method for determining the minimum miscibility pressure of a system comprising a gas and a liquid. A liquid-filled tube is equilibrated at a predetermined temperature and initial pressure, and pressure changes are determined as a single gas bubble is launched, rises through the tube, and stabilizes in the liquid. The measurements are repeated with fresh liquid at a series of different predetermined pressures. The minimum miscibility pressure is obtained either by finding the final pressure at which the time between launch and stabilization is constant or by evaluating the derivative of an empirically derived relationship between initial pressure and final pressure.

Abstract: A process is provided for recovering oil from a gas cap in a subterranean oil-bearing formation by injecting a water-alternating-gas cycle into the gas cap via an injection well in fluid communication therewith. The cycle includes a slug of an aqueous fluid and a slug of a non-aqueous gas. The aqueous fluid slug is substantially smaller in volume than the non-aqueous gas slug, the aqueous fluid slug being only of sufficient volume to substantially increase the water saturation of the gas cap without substantially increasing the gas saturation of the gas cap. The two slugs are injected into the gas cap sequentially, thereby displacing at least a portion of the oil in place from the gas cap into a production well. Any number of cycles are performed in sequence until the process is terminated.

Abstract: A method for rapidly and accurately determining the threshold and critical capillary pressures of a porous rock sample. A fluid saturating the sample, preferably oil, is withdrawn from the downstream end of the sample at an extremely low rate as a result of the introduction of another fluid, preferably gas, at the upstream end. The other fluid displaces the saturating fluid due to a differential pressure between the upstream and downstream ends of the sample. The differential pressure is created by means which does not require use of back pressure valves, thereby avoiding pressure surges and allowing constant slow withdrawal of the saturating fluid. The threshold and critical capillary pressures may be determined from a trace of the differential pressure.

Abstract: A process is provided for recovering liquid hydrocarbons from a subterranean hydrocarbon-bearing formation by sequential injection of a pair of immiscible gases of differing composition which displace the liquid hydrocarbons from the formation. The compositions of the displacement gases are selected such that one gas is characterized as a swelling gas and the other is characterized as a non-swelling gas with respect to the liquid hydrocarbons in place.

Abstract: A process for enriching a drive gas with intermediate hydrocarbon compounds to enhance the ability of the gas to mobilize hydrocarbons within a subterranean hydrocarbon-bearing formation. The drive gas is contacted with oil containing intermediate hydrocarbons under conditions such that the gas strips intermediate hydrocarbons from the oil. The drive gas may be further enriched upon contacting the gas with stripped oil which has been enriched with intermediate hydrocarbons under conditions such that the gas strips intermediate hydrocarbons from the enriched stripped oil.

Abstract: In the process of collecting data to be used in determining the capillary pressure of immiscible fluids in a porous rock sample, fluid is expelled from the sample by spinning a sample disk about its own center axis instead of centrifuging a core plug in the usual manner. The disk is contained in a cylindrical chamber whose dimensions are only slightly larger than those of the sample disk. A rotating shaft is connected to the center of the bottom face of the chamber and vessels are connected to the chamber about its periphery to collect the expelled fluid.

Abstract: An apparatus and method for determining the minimum miscibility pressure of a gas in a liquid comprises injecting a gas bubble into a transparent tube containing the liquid at a fixed predetermined pressure and temperature and observing the bubble behavior as it passes through the liquid in the tube. Thereafter, the pressure is increased and the procedure is repeated until the lowest pressure at which a bubble exhibits characteristic miscibility behavior in the liquid is determined, which is defined as the minimum miscibility pressure.

Abstract: A method of determining the minimum level of enrichment required to render a substantially immiscible gas miscible in a liquid hydrocarbon by observing the behavior of enriched gas bubbles having incrementally increasing levels of enrichment as they rise through samples of liquid hydrocarbon. The lowest level of enrichment at which a bubble is observed to dissipate in the liquid hydrocarbon is the minimum level of enrichment.

Abstract: A method of determining the minimum level of enrichment required to render a substantially miscible gas miscible in a liquid hydrocarbon by observing the behavior of liquid hydrocarbon droplets as they fall through samples of enriched gas of incrementally increasing levels of enrichment. The lowest level of enrichment at which the droplet is observed to dissipate in the enriched gas is the minimum level of enrichment.