Crack-contained real sandstone core physical simulation and oil displacement effect evaluation method

Abstract

The invention discloses a crack-contained real sandstone core physical simulation and oil displacement effect evaluation method. According to the method, first, a crack-contained real sandstone core is selected, and working fluid containing Mn<2+> is prepared; the core is vacuumized, the working fluid is saturated, and centrifugation is performed on the core to establish irreducible water saturation; the core is vacuumized, saturated experimental oil is pressurized, and original oil saturation is calculated; a nuclear magnetic resonance T<2> spectrum of a core sample is tested, and original oil distribution is obtained; water containing Mn<2+> is injected into the core sample, and oil displacement by water is performed till an outlet contains water by 100%; another nuclear magnetic resonance T<2> spectrum of the core sample is tested, and remaining oil distribution after oil displacement by water is obtained; a profile control agent is injected into the core sample, and subsequent oildisplacement by water is performed till the outlet contains water by 100%; another nuclear magnetic resonance T<2> spectrum of the core sample is tested, and remaining oil distribution after profile control and displacement is obtained; and according to the T<2> spectrum obtained at each stage, the oil displacement effect after oil displacement by water and the oil displacement effect after profile control and displacement are quantitatively analyzed, including oil displacement efficiency in cracks and matrix pores at each oil displacement stage. Through the method, the oil displacement effectof the crack-contained sandstone core can be evaluated quantitatively and accurately.

Description

technical field [0001] The invention belongs to the technical field of oil and gas field development experiments, and in particular relates to a physical simulation of real sandstone cores containing fractures and an oil displacement effect evaluation method. Background technique [0002] Low-permeability sandstone reservoirs have huge resource potential and are relatively difficult to develop. Most of the proven petroleum reserves in the past year are also low-permeability oilfield reserves, and low-permeability sandstone reservoirs often have fractures. There are problems such as channeling of injected water, premature water flooding of oil wells, and short production period without water. In response to this, a large number of physical simulation experiments have been carried out on low-permeability fractured sandstone reservoirs in the laboratory, but most of them use sand-packed pipes or artificially cemented core models, which cannot represent the actual reservoir char...

AI Technical Summary

Problems solved by technology

Therefore, none of the above-mentioned methods or techniques involves the physical simulation of real rock cores containing fractures and the evaluation methods of oil displacement effects.

Images