Effect of Kinetics of Permeability Alteration on Development of Clayey Oil Formation

Abstract

Formation damage, a common problem associated with field operations, is often a major factor in reducing the productivity and injectivity of a well in a petroleum reservoir. Numerous laboratory and field studies indicate that formation damage occurs during many phases of reservoir development – drilling, completion, workover, production, stimulation, waterflooding, or improved oil recovery. Formation damage is a process of initial permeability reduction. At present many mathematic formation damage models are developed. В настоящее время разработано множество математических моделей изменения проницаемости. This models contain a number of parameters: the rate constant for re-entrainment, the rate constant for liquid absorption, the phenomenological constants for swelling potential and the release constant for swellable fines, the rate constant for release rate, the rate constant for change in pore size with depositional morphology, the critical pressure force required to mobilize fines, plugging efficiency, the critical total pore volume flux for the onset of swelling, and the coefficient of volumetric thermal expansion. In order to describe formation damage, the parameters must be known. That is very problematic. We analyzed a number of laboratory experiments and formation damage studies. Comparing the results we defined that permeability has similar kinetics of alteration for different damaging mechanism. Next we determined the principal damaging mechanisms of real oil formation and associated them with laboratory relations of permeability alteration. As a result the integrated relations of permeability reduction were obtained. This method can be used as a predictive tool for quantitative predictions of field development showings for different rock types and operation strategies. Equations of permeability kinetics were entered into computer hydrodynamic model of oil formation. The effect of permeability kinetics on formation development process was shown concerning clay oil formation. Based on laboratory and field observations the methods of enhanced oil recovery and formation damage prevention were proposed.