Method for measuring capillary pressure and wettability of rock core under condition of temperature and pressure of oil deposit

Abstract

The invention provides a method for measuring the capillary pressure and wettability of a rock core, which comprises the following steps of: cleaning a rock specimen, drying, evacuating and saturating a first fluid; putting the saturated rock core into a rock core clamp holder of rock core displacement equipment, setting the experience temperature, saturating the dead volume of pipe lines at upstream and downstream ends of the rock core completely, and simultaneously, setting the pressure to maintain that the first fluid is injected under constant pressure; when the differential pressure of the upstream and downstream and the flow of the outlet end of the rock core are stabilized, injecting a second fluid under the condition of the same injection pressure; after the second fluid flows into the end face of the inlet end of the rock core, shutting a valve at the downstream end of the rock core, and recording the variation of the pressure and differential pressure of the upstream and the downstream ends of the rock core; and judging the capillary pressure and wettability of the rock core according to the pressure or differential pressure of the upstream and the downstream ends of the rock core. In the method, the capillary pressure and wettability of the rock core can be measured simultaneously under the condition of formation temperature and pressure, so the method has a simple process and is easy, quick and accurate to operate.

Description

technical field The invention relates to a method for measuring capillary pressure and wettability of rock cores, in particular to a method for measuring capillary pressure and wettability of low-permeability, ultra-low-permeability or ultra-low-permeability rock cores under the temperature and pressure conditions of oil reservoirs. Background technique Capillary pressure refers to the pressure difference between the non-wetting phase and the wetting phase on both sides of the curved liquid surface. It is the additional pressure to balance the pressure difference on both sides of the curved liquid surface, and its direction points to the concave direction of the curved surface. At present, there are mainly three methods for measuring rock capillary pressure ([1] SY / T 5346-2005; [2] Yang Shenglai, Wei Junzhi. Reservoir Physics [M]. Beijing: Petroleum Industry Press, 2004: 217-222 ): semi-permeable partition method, mercury intrusion method, centrifugation method. They all us...

AI Technical Summary

Problems solved by technology

The semi-permeable diaphragm method, mercury injection method, and centrifugation method have a big defect in the capillary pressure test: the test result is not the static capillary pressure in the true sense, because when the capillary force is measured, the fluid is in a state of motion, due to the contact angle There is a certain difference between the test result and the real static capillary pressure due to hysteresis and other reasons

The relative permeability method is only suitable for distinguishing strongly water-wet and strongly oil-wet cores, and small changes in wettability are difficult to detect with these methods

The test period of the relative permeability curve measurement method is relatively long, and for low-permeability cores, because the influence of capillary pressure on seepage is ignored in the calculation formula of the relative permeability curve, the reliability of the relative permeability curve is reduced

Images