Method for accurately measuring nuclear magnetic resonance porosity of oil-containing shale

Abstract

The invention provides a method for accurately measuring the nuclear magnetic resonance porosity of oil-containing shale. According to the method, nuclear magnetic resonance T2 spectral distribution and porosity of kerosene shale different in waiting time and echo interval are measured, the oil-containing shale porosity is compared with the helium porosity with respect to calibration waiting time and echo intervals, and the nuclear magnetic resonance T2 spectral distribution obtained at the time of the optimum echo time and the echo interval can represent reservoir physical property traits of the oil-containing shale. According to the method, factors influencing the measuring accuracy of the nuclear magnetic resonance porosity of the oil-containing shale are ascribed to the type and measurement parameters (waiting time and echo intervals) of sample saturated fluid, and the hydration influence of a shale sample is eliminated through saturated kerosene; the optimum waiting time and echo intervals are calibrated by analyzing T2 spectral distribution variation and the helium porosity; by means of the method, nuclear magnetic resonance T2 spectral distribution and porosity of the kerosene shale different in waiting time and echo interval are measured, thus the optimum measurement parameters which can accurately represent the porosity of the oil-containing shale can be obtained, test operation is simple and easy to conduct, and operability is great.

Description

technical field [0001] The invention relates to an accurate test method for nuclear magnetic resonance porosity of oil-bearing shale, and belongs to the technical field of nuclear magnetic resonance test of shale reservoir physical properties laboratory. Background technique [0002] The successful exploration and development of shale oil and gas in North America has greatly promoted the process of global shale oil and gas exploration and development. The exploitation and utilization of shale oil and gas are of great significance to alleviating the energy crisis, prolonging the life of the petroleum industry and adjusting the national energy structure. [0003] Shale oil and gas refers to the accumulation of hydrocarbons in shale formations, including oil and gas in thin interlayers of sandstone and carbonate rocks in shale formations. Different from conventional reservoirs, shale reservoirs have complex mineral composition, ultra-low porosity, ultra-low permeability, and r...

AI Technical Summary

Problems solved by technology

[0004] At present, domestic and foreign scholars have carried out a large number of shale NMR tests based on conventional reservoir NMR test methods, and obtained NMR T values ​​of shale saturated fluids with different morphological characteristics. 2 These test methods generally have the following defects: the sample pretreatment is not carried out before the test, and the pore fluid of the sample is removed, making it difficult to meet the requirement of a single saturated fluid during the sample test; the sample is saturated with water or brine, ignoring the influence of clay mineral hydration ; The test parameters of waiting time and echo interval mostly use conventional reservoir test parameters or unspecified test parameters, ignoring the influence of test parameters on NMR test results

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