Mercury injection capillary pressure curve roughening method

Abstract

The invention discloses a mercury injection capillary pressure curve coarsening method. The method comprises the following steps: a, determining the number N of original sample curves; b, assigning aweight coefficient Wi of each original curve to obtain a synthetic sample; c, calculating the weighted porosity phi c of the synthetic sample; d, determining M pressure points Pj by taking [delta]P asa pressure incremental quantity from the zero pressure point; and e, circulating the pressure points one by one, summing the mercury injection volume of the synthetic sample at each pressure point Pj, and calculating the mercury saturation corresponding to the coarsened curve at the pressure point Pj. According to the method, an original curve does not need to be fitted, meanwhile, the reservoirthickness and porosity represented by the original curve are also considered, and roughening treatment can be directly carried out on capillary pressure curves of any form and any number.

Description

technical field [0001] The invention relates to a mercury injection capillary pressure curve roughening method, which belongs to the field of pore structure evaluation and saturation evaluation of oil and gas reservoirs. Background technique [0002] For the study of reservoir rock pore structure, the capillary pressure curve is the basis for studying the throat size, and different curve shape features reflect different pore structure characteristics of rocks. There are many measurement methods for capillary pressure, including semi-permeable diaphragm method, centrifuge method, mercury intrusion method, dynamic capillary pressure method and steam pressure method, etc. Among them, mercury porosimetry is one of the most commonly used methods for studying rock pore structure in major oilfields because of its simple operation, short time consumption, and high measurement pressure, which can measure smaller throats. [0003] Conventional mercury porosimetry is based on the capi...

AI Technical Summary

Problems solved by technology

These three methods all use curve fitting methods, which are greatly affected by the shape of the original capillary pressure curve and the fitting initial pressure, especially for curves with complex shapes. The curve is poorly represented

Li Sihan (2020) proposed a capillary pressure curve roughening method based on the effective thickness of the reservoir, which only performs a thickness-weighted average of the saturation, without considering the influence of porosity of different samples, resulting in poor representativeness of the roughened curve

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