Pore structure and its effect on reservoir permeability of basalts

Time:	2018-2020
Fund:	230 Thousend Yuan
Project No.:	41702128
Type:	NSFC
Leader:	Yulong Huang
Participant:	Yulong Huang,Haibo Liu,Yongkang Yin,Kailun He

Multiple pore network of basalts is composed of diverse pores and fractures with different scales, which is significant to reserving of hydrocarbons, ground water and heat resources, and also to permanent carbon dioxide storage. As the key factor which determines the reservoir and sealing capacities, the permeability of basalts is close related to their pore structures. Comparatively study the outcrop samples of Jingpohu Holocene basalts and borehole core samples from Liaohe Depression, which were formed in similar tectonic background due to the Tanlu fault zone. Serial sectioning of resin-impregnated plugs and scanning electron microscope are used to
decomposition and characterization of pore network. On the basis of description and summarization of pore types, shapes, occurrences and identifying marks, the pore network of basalt is decomposed into four units
such as macro pores, fractures, intra-phenocrystal porosities and matrix porosities. Characteristics of these four porosity units and their connections and proportions are used to the description and modeling of pore networks. High-pressure mercury injection, low-temperature nitrogen adsorption, porosity and permeability tests are used to obtain quantitative parameters of pore structure and reservoir permeability, which are further applied to principal component analysis and grey relational analysis, thus enabling the classification and evaluation of pore structures, summarization of their characteristic parameter ranges and modeling of typical pore networks.Moreover, impacts of diagenesis on pore structures are studied by energy spectrum, cathodoluminescence (CL), whole rock mineral analysis and experiments of rock mechanics. Finally, synthetic studies enable the discoveries of heterogeneities of pore structures and permeabilities as well as their controlling factors, and indicating the distribution of high permeable reservoir bodies and low permeable barriers.