Abstract: A process of utilizing natural gas to obtain a miscible drive fluid for low pressure reservoirs is described. The process involves upgrading natural gas to ethane, propane and butane constituents which are fabricated into a mixture which is miscible at the reservoir conditions. The process is operated so as to maximize the reuse of the upgraded miscible drive fluid and therefore lower the cost of enhancing the oil recovery from a low pressure reservoir.

Abstract: An apparatus is disclosed for measuring physical properties of a sample material at controllable temperatures and pressures. The apparatus includes a sample cell for holding fluid and/or solid samples. The cell includes at least one optically transparent window permitting visual and electromagnetic energy observations of the sample. A probe functions within the cell to collect a subsample for movement to apparatus for measuring properties and for returning the subsample to the cell. One form of optically transparent window is a sapphire. The cell is intended for measurements of physical properties at temperatures from about -40.degree. F. to about +400.degree. F. and at pressures from vacuum to at least 20,000 pounds per square inch.