A review of the progress in flow behavior evaluation using the transient method in the tight sandstone and shale formations
JIA Bao, ZHAO Yu, XIAN Chenggang, YU Kai, CAO Wei, JIA Wenfeng, ZUO Xuan
1 State Key Laboratory of Petroleum Resource and Engineering, China University of Petroleum-Beijing, Beijing 102249, China 2 Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China 3 Exploration and Development Research Institute of Daqing Oilfield Co Ltd, Daqing 163712, China 4 Heilongjiang Key Laboratory of Reservoir Physics & Fluid Mechanics in Porous Medium, Daqing 163712, China 5 Research Institute of Exploration and Development, PetroChina Southwest Oil and Gas Field Company, Chengdu 610041, China 6 Oil and Gas Technology Research Institute, PetroChina Changqing Oilfield Company, Xi’an 710018, China
Tight sandstone and shale reservoirs have gradually become the main sources of global oil and gas production growth. Accurate reservoir evaluation is the key to achieving efficient development of oil and gas fields, and experimental measurement of the fluid flow capacity of oil and gas reservoirs is one of the important aspects of reservoir evaluation work. Traditional permeability measurement methods are based on the steady-state method, that is, the permeability is calculated based on Darcy’s law when the pressure drop at the inlet and outlet of the core reaches equilibrium. However, for ultra-low permeability and shale reservoirs, the steady-state method is difficult to apply. Therefore, transient method needs to be used instead of the steady-state method, and the pressure pulse decay experimental device has become a commonly used means to study ultra-low permeability. This paper comprehensively analyzes the development process of pressure pulse decay experiments in the past 50 years, and focuses on the representative research results. In view of the deficiencies of the existing technical means, this paper proposes the research direction of strengthening the fundamental research into fluid flow in ultra-low permeability porous media. Currently, one-dimensional analytical solutions and numerical models can calculate ultra-low permeability with high precision, and two-dimensional and three-dimensional models are also rapidly developing. However, the efficient embedding of complex-shaped and multiscale fractures into pressure pulse decay models is still a key problem to be solved. For adsorptive gases such as shale gas, it is a fundamental scientific problem that needs to be further explored to clarify the difference between static adsorption and dynamic adsorption and effectively incorporate the adsorption curve into the flow model. Based on this, the rock physics characteristics under multi-physical effects can be evaluated through pressure pulse decay experiments. In addition, the systematic study of non-Darcy flow behavior under relatively low pressure conditions is also an important way to promote scientific calculation of pressure pulse decay experiments. Over the past few decades, significant progress has been made in the experimental and simulated evaluation of the storage and permeability of ultra-low permeability rock cores. Further theoretical research and the development of advanced experimental devices will be important. The progress of related research has important strategic significance for the efficient exploration and development of China’s tight and shale oil and gas reservoirs and the guarantee of national energy security.
