Standards Development

Scope

Standardization of the principle, equipment and material requirements, sampling, experimental steps, data calculation and report of determination of porosity of shale by helium pycnometry.

This document can be used for resource evaluation, fine characterization of reservoirs, reserve calculation, target selection, etc. in shale gas exploration and development. 

Purpose

Shale gas is a clean and efficient new energy resource, mainly used for residential gas, urban heating, power generation, automotive fuel, chemical materials, etc. It is natural gas extracted from the black shale layer, mainly composed of methane, with a content generally above 85%, up to 99.8%. The combustion produces fewer pollutants, making it a clean energy source that can reduce atmospheric pollution. According to the shale gas resource assessment report released by the International Energy Information Agency (EIA) in 2015, shale gas resources are widely distributed worldwide, with a global technically recoverable resource of 220.69 trillion cubic meters, including 65 trillion cubic meters in North America, 41 trillion cubic meters in South America, 40 trillion cubic meters in Asia, 38 trillion cubic meters in Africa, and 25 trillion cubic meters in Europe. The United States is the earliest country to achieve commercial development of shale gas. Through shale gas development, the United States has initiated the "shale oil and gas revolution", changing the natural gas supply pattern and causing significant changes in the global energy supply pattern. Inspired by the successful cases of shale gas exploration and development in the United States, countries such as Germany, the United Kingdom, France, Sweden, Austria and Poland in Europe, China in Asia, Argentina in South America, Australia and New Zealand in Oceania, and South Africa in Africa have all evaluated their shale gas resources. Canada, China, Argentina, Saudi Arabia, and the United Arab Emirates have successively begun the stage of industrial scale extraction. According to EIA (2016) data, it is expected that global shale gas production will reach 1.6 trillion cubic meters by 2040. Shale gas has become one of the most important unconventional oil and gas resources in the world's energy transition, and an important clean energy source in the processes of carbon peaking and carbon neutrality. Porosity is one of the most fundamental and important parameters for shale gas geological evaluation and reserve calculation. However, shale mainly develops micro nano scale pores with complex pore structures and low permeability, making precise testing of its porosity more difficult than conventional reservoirs. The current methods for determining shale porosity include liquid saturation method, helium gas method, and nuclear magnetic resonance method. The liquid saturation method is relatively simple to operate, but it is not suitable for accurate measurement of shale porosity due to the difficulty of liquid molecules entering micro and nano scale pores, making it difficult to measure some pores, making it difficult to wipe the surface liquid clean during the testing process, which can cause errors, and the possibility of liquid damage to the sample. The technology of nuclear magnetic resonance is still being developed, and there are differences in the methods used by different countries and students to interpret porosity using nuclear magnetic resonance technology, as it is currently not suitable to establish standards. At present, the helium method has been widely used internationally compared to the other two methods due to its high measurement accuracy, high technological maturity, simple and relatively low cost measuring instruments and equipment, and the measurement process not causing damage to the core. Almost all countries engaged in research and production of shale oil and tight oil and gas have applied this technology. However, there is currently no unified international standard established to specify the technical method for shale helium method porosity measurement, as this selection focuses on developing international standards for shale helium method porosity measurement. By formulating this standard, standardizing and unifying the experimental methods, processes, and requirements for measuring shale helium porosity, reliable references can be provided for global shale porosity measurement, and the global comparability of experimental results can be improved, providing solid support for accurately evaluating global shale gas resources.