Application of pulse-decay technique to characterize whole cores.

摘要

The application of pulse-decay method has been extended from linear core plugs to full diameter whole cores. A mathematical model, which incorporates the slippage effects, has been developed to solve the problem of transverse, unsteady compressible fluid flow through whole cores. Experimental set-up has also been constructed for performing pulse-decay experiments on whole cores. A numerical model adopting a curvilinear grid has been developed to solve the governing non-linear flow equation. Based on this numerical solution, a data analysis computer program has also been developed which calculates the permeability and Klinkenberg factor from measured pulse-decay experimental data using non-linear regression technique. Pulse-decay experiments were conducted on sandstone samples under the conditions where the data were influenced by gas slippage effects, using gas as the pore fluid. A technique has also been presented for the estimation of permeability and Klinkenberg factor from multiple pressure pulse-decay tests. The obtained results are compared with the conventional steady-state values. The proposed method is much faster and easier to perform as compared to the conventional steady-state method and can also help detect core heterogeneity.