Method for qualitatively recognizing high-temperature high-pressure methane gas layer and carbon dioxide gas layer

Abstract

The invention provides a method for qualitatively recognizing a high-temperature high-pressure methane gas layer and carbon dioxide gas layer. The method comprises the following steps: 1) conducting standard processing on well logging data; (2) analyzing the data scale well logging interpretation result through a rock core assay, and precisely calculating the effective porosity and the gas saturation of a storage layer; 3) eliminating influence on density and neutron well logging data by well hole environment and slurry; (4) utilizing the response characteristic difference of the methane gas layer and the carbon dioxide gas layer by density and neutron well logging data to calculate a neutron and density curve interval NDS curve of the high-temperature high-pressure gas layer sections, and then dividing the NDS curve by porosity and gas saturation so as to obtain an NDS_Sg curve. The distinguishment standards of the methane gas layer and the carbon dioxide gas layer are established through the comparison of size of the NDS_Sg curve of gas-bearing pores, the distinguishment precision of the high-temperature high-pressure methane gas layer and carbon dioxide gas layer can be obviously improved, and the coincidence rate is improved from the conventional 50% to 85% or higher.

Description

technical field [0001] The invention relates to the technical field of oil and gas well logging and core test analysis, in particular to a method for qualitatively identifying high-temperature and high-pressure methane gas layers and carbon dioxide gas layers. Background technique [0002] Methane (CH 4 ) atmosphere and carbon dioxide (CO 2 ) gas reservoir identification is one of the key technologies for the exploration and development of high temperature and high pressure gas reservoirs in the western South China Sea Basin. Using methane (CH 4 ) atmosphere and carbon dioxide (CO 2 ) The different response characteristics of gas reservoirs to density and neutron logging is one of the common methods to distinguish the gas composition types of gas reservoirs. [0003] Using density and neutron curves to calculate the NDS value of the gas layer section and the method of discriminating the gas component types of the gas layer belongs to the innovation of scientific research...

AI Technical Summary

Problems solved by technology

However, the neutron and density curves are affected by factors such as lithology, wellbore conditions, and mud immersion at the same time, so the direct use of the original logging curve to determine the gas composition type of the gas layer is not high. According to statistics, the gas composition of the gas layer The coincidence rate of type discrimination usually only reaches about 50%, which brings great difficulties to the development and production of natural gas

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