Method for judging reservoir fluid type of difference between density porosity and neutron porosity

Abstract

The invention discloses a method for judging the reservoir fluid type of a difference between density porosity and neutron porosity and relates to the technical fields of oil and gas logging and geology and core test analysis. The method comprises the following steps: 1) accurately calculating the shale content, the rock composition, the density porosity and the neutron porosity of a reservoir by core data calibrating logging and logging data environmental correction; 2) removing the influence of factors of lithology, well diameter and mud invasion on density and neutron data; and 3) establishing standards for judging the reservoir fluid type by utilizing the response difference of the density and the neutron data to gas and formation water and by comparing the values of the density porosity and the neutron porosity. When the invention judges the reservoir fluid type by utilizing the density and the neutron data, non-fluid influencing factors, such as lithology, borehole conditions, mud invasion and the like are removed, therefore, influence features of different fluids to the density and the neutron data can be truly reflected, and the coincidence rate for judging the reservoir fluid type can be enhanced to above 90 percent from the existing 70 percent.

Description

technical field [0001] The invention relates to the technical fields of oil and gas well logging, geology and core test analysis, in particular to a method for judging reservoir fluid types by using the difference between density porosity and neutron porosity. Background technique [0002] Reservoir fluid type discrimination is one of the key technologies in natural gas exploration and development. Using the different influences of natural gas and formation water on density and neutron data is one of the commonly used methods to identify reservoir fluid types. [0003] The density porosity-neutron porosity difference fluid type discrimination method belongs to the innovation of scientific research methods in the field of natural gas exploration and development. It mainly uses logging data, combined with geological data and core experiment data to study the density and neutron Based on the different impact characteristics of the data, the relationship between the density of ...

AI Technical Summary

Problems solved by technology

However, at present, when the porosity is large, the neutron logging value is relatively large, and factors such as lithology, wellbore conditions, and mud immersion have a great influence on the density and neutron data, so the curve shape is directly used to judge the reservoir fluid The type matching rate is not high. According to statistics, the matching rate of reservoir fluid type identification usually only reaches about 70%, which brings great difficulties to the development and production of natural gas

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