Calibration method of core-based gas permeability measuring device

Abstract

The invention discloses a calibration method of a core-based gas permeability measuring device. The calibration method comprises the following steps of clearing away air in a pipeline by adopting nitrogen; collecting cross section areas and lengths of to-be-measured cores and clamping the to-be-measured cores in a core holder; controlling the inlet pressure of the core holder by adjusting a gas permeability tester, and collecting pressure values and the core outlet flow rate; fitting out the functional relationship by quadratic difference of the core outlet flow rate and the steady inlet and outlet pressure. According to the functional relationship and the Darcy law, the corresponding inlet pressure and the gas-measured permeability are calculated at the utmost pressure, the relation function of the gas-measured permeability and the reciprocal value of the average pressure is created, and the nodal increment of the horizontal segment of the section function is regarded as Kerr permeability. The absolute core permeability can be quickly and accurately obtained by the gas-measured permeability calibration method-a theoretical limit method.

Description

Technical field [0001] The invention relates to a method for measuring the absolute permeability of a core, in particular to obtain the Kelvin permeability of a target core through a calibration method based on a core gas permeability measurement device. Background technique [0002] Core permeability is an important parameter in the evaluation and development of oil and gas fields. In the process of formulating oilfield development plans, it is first necessary to conduct core gas permeability experiments to evaluate the absolute permeability of the core to be tested and provide basic data for development plans and other work . The commonly used experimental method is: use the experimental device to measure the inlet pressure (the outlet pressure is atmospheric pressure) at the two ends of the five to ten sets of cores, and the volumetric flow data of the gas in the core. Then, the Darcy formula is used to calculate the gas permeability under different inlet pressures, and then ...

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Problems solved by technology

In order to achieve this condition, the inlet pressure setting value of the gas permeability test should be set from a lower pressure as far as possible to ensure that the fluid seepage in the measured core is a linear flow, but the lower the pressure, the more obvious the slippage effect of the gas seepage. The greater the error caused by the method correction; the slippage effect of the gas is small at high pressure, but its linear flow stability is poor

Therefore, there are still the following problems in the determination of gas permeability: ① The data points of the inlet pressure and gas volume flow rate of the core obtained by the experiment satisfying the conditions of Darcy's law are few in number, and there are human errors in the experimental process, which will affect the experimental results. great influence

② In particular, the gas permeability experiment of low-permeability cores takes a long time and cannot minimize the relative error

③Kirls Permeability is the inherent property of the corresponding rock core under the ultimate pressure. If the inlet pressure can be infinitely increased while ensuring linear flow, the closer the obtained permeability is to the Kr. A condition cannot be achieved by existing experimental conditions

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