Method for multi-scale representing of dense reservoir pore throat characteristics based on high-pressure mercury intrusion

Abstract

The invention provides a method for multi-scale representing of dense reservoir pore throat characteristics based on high-pressure mercury intrusion. The method comprises the following steps that thepermeability K and the porosity phi of a rock core are determined under the original stratum covering condition; a high-pressure mercury intrusion experiment is carried out on the rock core to obtainthe external mercury inlet pressure Pi, the hole throat radius ri in the case of the mercury inlet pressure Pi, and the mercury inlet saturation increment delta Si in the case when the mercury inlet pressure is changed from Pi-1 to Pi; the relevant new parameters of pores and throats of stages, and pore throats of stages are calculated, then correlation analysis with the porosity phi and the permeability K are conducted, and main control factors of the permeability of a reservoir are determined; and the real existence of the pore throats of stages is verified by the aid of a scanning electronmicroscope, the width of hole diameters of the pore throats is measured, and the width is compared with the hole diameter distribution obtained by the above algorithm. According to the method, mathematical, physical and other theoretical formulas are applied for processing relevant mercury intrusion data based on data provided by the high-pressure mercury intrusion, so that a new algorithm is formed to represent micro-pore throat characteristics and the permeability of fluid in a micro-pore throat.

Description

technical field [0001] The invention belongs to the technical field of unconventional oil and gas exploration and development, and in particular relates to a multi-scale characterization method for pore throat characteristics of tight reservoirs based on high-pressure mercury injection. Background technique [0002] In the study of the microcosm, scanning electron microscopy has always been a powerful tool for people to explore its mysteries, and mercury porosimetry has been widely used in oil and gas geology. As early as 1976, Wardiaw believed through experiments that during the process of mercury ejection, the capillary pressure of the throat is greater than that of the pores, so mercury mainly exits from the throat, while the voids are still filled with mercury. [0003] Mercury porosimetry is to inject mercury into the vacuumed rock pore system under the action of external pressure. When the external pressure and capillary pressure reach equilibrium, the pore-throat radi...

AI Technical Summary

Problems solved by technology

For tight sandstone reservoirs, high-pressure mercury intrusion injection (up to 400MPa) can characterize almost all effective pores, and the highest accuracy can reach 3nm. The destructive effect on microscopic pore throats will inevitably have certain errors, and at the same time, it is impossible to directly obtain the seepage characteristics of the fluid in it and verify the real existence of pore throats at all levels

Images