Mobil Oil Corporation

Melwyn L Mathis

Bert J Warner

Alvin S Cullick

Henry A Seal

Warren F Johnson

Eddie F Schultz

Curtis L Humphries

A method for determining the CO.sub.2 minimum miscibility pressure (MMP) is disclosed which comprises filling a coiled capillary tube with oil at a predetermined temperature T.sub.1 and an initial predetermined pressure P.sub.1 less than the CO.sub.2 MMP. Carbon dioxide is injected into the capillary tube at a fixed flow rate F.sub.1 to displace the oil while maintaining the temperature of the oil at T.sub.1 and the pressure at P.sub.1. The pressure drop across the capillary tube and the volume of carbon dioxide injected is constantly measured. The pressure difference versus volume of carbon dioxide injected data is plotted and the pressure drop .DELTA.P.sub.1 at the point of inflection where the second derivative goes from a negative value to a positive value is determined graphically. The previous steps are repeated while maintaining T.sub.1 and F.sub.1 constant at a different pressure P.sub.2 less than the CO.sub.2 MMP and .DELTA.P.sub.2 at the inflection point of pressure versus volume of CO.sub.2 injected is determined. Additional CO.sub.2 displacement tests are conducted at the same temperature T.sub.1 and CO.sub.2 flow rate F.sub.1 at various pressure levels (at least two) above the CO.sub.2 MMP. The pressure drop at each pressure P.sub.3 and P.sub.4 above the CO.sub.2 MMP is plotted versus the volume of carbon dioxide injected. The pressure drop .DELTA.P.sub.3 and .DELTA.P.sub.4 at the point of inflection as previously defined is determined for the corresponding pressure P.sub.3 and P.sub.4. The corresponding pressure drop at the inflection point obtained for the pressure values below MMP and the pressure drop at the inflection point obtained for the pressure values above MMP minus the pressure drop for CO.sub.2 under the same test conditions as calculated by the Hagen-Poiseuille equation are plotted as a linear function of test pressure. The CO.sub.2 MMP is determined graphically as the pressure at the point where the two lines defining miscible and immiscible displacement intersect.

Method and apparatus for determining CO.sub.2 minimum miscibility

A method for determining the foaming characteristics of a crude oil stream at the wellhead comprising introducing the production crude oil stream from the wellhead into an elongated, horizontal separator under reduced pressure at a controlled flow rate, withdrawing evolved gas from the upper portion of the separator and measuring the flow rate thereof, withdrawing oil from the lower portion of the separator and measuring the flow rate thereof, controlling the pressure on the separator at a lower pressure than the wellhead pressure, controlling the liquid level of the oil in the separator, measuring the volume of oil in the separator, and measuring the volume of foam in the separator. The apparatus comprises an elongated horizontal separator, a crude oil inlet into one end of the separator, means for supplying a crude oil stream from the wellhead to the crude oil inlet in the separator at a controlled flow rate, means for controlling the pressure in the separator at a pressure lower than the wellhead pressure, means for withdrawing gas from the upper portion of the separator and measuring the flow rate thereof, means for withdrawing crude oil from the lower portion of the separator and measuring the flow rate thereof, means for controlling the liquid level crude oil in the separator, means for measuring the volume of foam formed in the separator, and means for measuring the volume of crude oil in the separator.

Method and apparatus for determining the foaming characteristics of a

Method and apparatus for mixing a gaseous oxidant (e.g., oxygen) and a lixiviant (e.g., an aqueous carbonate solution) at a downhole location before the oxygen-saturated lixiviant is injected into a formation to be leached. The invention involves establishing a mixing zone in the well by positioning a mixing means, comprising a housing, in the well at the downhole location. Lixiviant is flowed down the well and through a restrictive opening in the housing to substantially increase the flow velocity of the lixiviant. At the same time, gaseous oxidant is fed to the housing and is trapped therein by the increased velocity of the lixiviant and by packing material in said housing. The lixiviant flows through the trapped oxidant which, in turn, dissolves into the lixiviant to saturate same. Additional packing material is provided in the housing to remove undissolved oxidant from the saturated lixiviant before it is injected into a formation to be leached.

Growing community of inventors

Arlington, TX, United States of America

Melwyn L Mathis