[Show abstract][Hide abstract] ABSTRACT: This paper describes a simulation study on the effect of visbreaking on heavy oil recovery during steam injection processes. The kinetic data constant for in-situ visbreaking was derived from in-house kinetic data and then used in conjunction with a thermal compositional simulator to assess the effect of visbreaking on recovery through a series of numerical experiments. Various steam injection strategies were tested and the effect of visbreaking studied. In some cases, physical heating, not thermal visbreaking, was the dominant recovery mechanism. In other cases, visbreaking had a large effect on recovery. The difference was primarily a result of the placement of the visbroken oil with respect to the direction of flow. In cases where the visbroken oil zone was perpendicular to the flow, it formed a mobility transition zone that improved sweep, thus enhancing oil recovery.
[Show abstract][Hide abstract] ABSTRACT: When optimal salinity, C/sub phi/, and solubilization parameter, V/sub o//V/sub s/, are augmented by oil molar volume, v/sub o/, the resultingthree-parameter representation provides a more nearly unique description of microemulsion phase behavior than has previously been available. It then becomes possible to introducr the idea of equivalent oils as a replacement for th equivalent alkane carbon number, which is shown to lack some of the properties needed to implement efficient preliminary screening of microemulsions for enhanced oil recovery. Broadly speaking, two oils are considered equivalent if they have equal viscosity and provide the same phase behavior as a function of surfactant concentration and salinity in the neighborhood of the optimal salinity locus. It is anticipated that, when these conditions are satisfied, flooding results will also be the same. It should then be possible to replace microemulsion floods of live crude at high pressure with floods of appropriately diluted dead crude at low pressure. This paper places equivalent alkane carbon number in perspective by means of the three-parameter representation; explores parallel effects of temperature and alcohol cosolvents; compares different kinds of lipophile branching; and reveals essential non-linearities in optimal salinity as a function of oil composition (and hence molar volume) for mixtures of various oils. Much of this is subsequently used to develop methods for preparation of equivalent oils and the more complex but evidently essential equivalent systems needed to model live crudes.
Society of Petroleum Engineers Journal 04/2013; 23(04). DOI:10.2118/10678-PA
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