Method for determining 100% pure water spectrum through nuclear magnetic resonance logging spectrum T2

Abstract

The invention discloses a method for determining the 100% pure water spectrum through the nuclear magnetic resonance logging spectrum T2. The method includes the following steps that firstly, the relation between the irreducible water saturation Swi of a reservoir stratum in an exploratory area and the geometric mean value T2g of the spectrum T2 is built according to known rock physical experiment characteristics, then the irreducible water saturation Swi of the logging spectrum T2 and the geometric mean value T2g of the spectrum T2 are calculated point by point by means of a bulb tube thin film model, the nuclear magnetic resonance centrifugal spectrum is built, and the 100% pure water nuclear magnetic resonance spectrum is built on the basis of the nuclear magnetic resonance centrifugal spectrum. A significant difference exists between a nuclear magnetic single and a 100% pure water nuclear magnetic signal when the reservoir stratum contains oil and gas, and accurate identification is carried out on fluid of the reservoir stratum by means of the difference. The 100% pure water spectrum is built through nuclear magnetic resonance logging information so that the real pore structure of the reservoir stratum can be reflected; in addition, by contrasting the difference between the actually measured nuclear magnetic resonance spectrum and the built pure water spectrum, the property of the fluid of the reservoir stratum is effectively identified, so that the problem that fluid identification during nuclear magnetic resonance logging is difficult due to crude oil properties and observing modes is solved, the application of the nuclear magnetic resonance logging information is improved, and the geological problem solving capacity is enhanced.

Description

technical field [0001] The invention relates to the fields of core nuclear magnetic resonance, nuclear magnetic resonance logging and reservoir evaluation, in particular to a nuclear magnetic resonance logging T 2 Method for determining the spectrum of 100% pure water. Background technique [0002] NMR is the response of atomic nuclei to electromagnetic waves in a magnetic field. The original data of NMR logging is a spin echo train whose amplitude decays with time. The spin echo train contains rich information such as reservoir physical properties, pore type, pore size, fluid type and its distribution, etc., which can be expressed as multiple Superposition of decay exponents: [0003] M ( t ) = Σ M i ( 0 ) e - t T ...

AI Technical Summary

Problems solved by technology

The advantage of method 2 is that a fully hydrated T can be obtained fundamentally 2 distribution, but the algorithm is complex and difficult to promote

The last method has strong regional applicability, does not have a universal law, and does not fundamentally solve the influence of hydrocarbon content on spectral distribution

[0014] In order to solve the T in nuclear magnetic logging application 2 The spectrum is affected by hydrocarbons and cannot reflect the actual problem of reservoir quality well. We should adopt a new research idea and method, avoid the traditional ideas and methods of core experiment or other information calibration, and propose a method to determine the hydrocarbon content correction of NMR logging. A reliable method and technique that overcomes the technical limitations of current methods

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