An accurate characterization method for oil-water phase-permeability relationship curve in ultra-high water-cut period

Abstract

The invention relates to the technical field of oil and gas field development, and specifically discloses a method for accurately characterizing the oil-water phase-permeability relationship curve in an ultra-high water-cut period. The method includes the following steps: Step 1, select the experimental data of high water injection multiple oil-water phase permeability in the target block or reservoir; Step 2, draw the relationship curve between the oil-water relative permeability ratio and water saturation; Step 3, fit the oil-water relative permeability The relationship curve between the permeability ratio and the water saturation; step 4, determine the relationship characterization equation between the oil-water relative permeability ratio and the water saturation. The beneficial effects brought by the technical solution of the present invention are: constructing a characterization equation that is more suitable for the relationship curve between the oil-water relative permeability ratio and water saturation in the ultra-high water-cut period, and accurately realizing the segmentation of the oil-water relative permeability ratio curve in semi-logarithmic coordinates The unified characterization of the nonlinear variation of the equation lays a good foundation for the derivation and establishment of reservoir engineering calculation methods in the ultra-high water-cut period.

Description

technical field [0001] The invention relates to the technical field of oil and gas field development, in particular to an accurate characterization method for the oil-water phase-permeability relationship curve in an ultra-high water-cut period, which is used to solve the problem of unified and accurate fitting of the oil-water relative permeability ratio and the water saturation relationship curve under high water injection scour times. Background technique [0002] With the deepening of the water flooding development process, more and more medium-high permeability sandstone reservoirs have entered the ultra-high water-cut development stage. After entering the ultra-high water-cut period, the oil layer has been scoured by water injection for a long time, and the lithology has changed. The semi-logarithmic relationship between the oil-water relative permeability ratio and water saturation is no longer completely linear, and the curve bends down. [0003] The invention patent...

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Problems solved by technology

[0004] At present, there are very few studies at home and abroad on the shape or change characterization of relative permeability curves under high water injection scour multiples. As mentioned above, the partially established relationship between oil-water relative permeability ratio and water saturation has complex forms and low fitting accuracy. It is difficult to meet the characterization accuracy requirements of relative permeability curves under high water injection flushing multiples, and it is urgent to establish a characterization method for oil-water phase-permeability curves that can accurately characterize multi-segment nonlinear characteristics, has a simple form, and is convenient for water flooding characteristic analysis, and re-understand long-term water injection. Theory of water flooding under scour conditions and new features of water flooding development in ultra-high water cut period

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