Dispersion Measurement as a Method of Quantifying Geologic Characterization and Defining Reservoir Heterogeneity. Annual Report, July 12, 1990--September 12, 1991

Download or read book Dispersion Measurement as a Method of Quantifying Geologic Characterization and Defining Reservoir Heterogeneity. Annual Report, July 12, 1990--September 12, 1991 written by and published by . This book was released on 1992 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since reservoirs are heterogeneous, nonuniform, and anisotropic, the success or failure of many enhanced oil recovery techniques rests on our prediction of internal variability and the paths of fluid flow in the reservoir. The main objective of this project is to develop a greater understanding of reservoir heterogeneities through dispersion measurement. In this annual report, an approach to ways to estimate the dispersivities of reservoir rocks from well logs is presented. From a series of rock property measurements and dispersion tests the following studies have been made: A measure of rock heterogeneity is developed by using the effluent concentration at one pore volume injection in a matched viscosity miscible displacement. By this approach, a heterogeneity factor is determined from the measured S-shaped dispersion curve. The parameter f in the Coats-Smith capacitance model is redefined as the dispersion fraction f{sub d} (or mechanical mixing fraction). At the f{sub d} pore volume injection, the dynamic miscible displacement efficiency reaches maximum. Reflected on the dispersion curve, this number corresponds to the peak of the first derivative of concentration. With the concept of dispersion fraction, a unique solution to the capacitance model is obtained, and then an equivalent dispersivity is defined. Through experimental data on Berea and Brown sandstone samples, it has been found that the equivalent dispersivity is an exponential function of the heterogeneity factor and can be used as a reservoir characteristic. Through a key parameter of tortuosity, dispersivity is related to rock petrophysical properties. This semi-theoretical relationship forms the basis for determining dispersivities from well logs. The approach is validated through experimental studies on Berea and Brown sandstone samples. It has been found that the equivalent dispersivity is an exponential function of the heterogeneity factor and can be used as a reservoir characteristic.