准噶尔盆地二叠系风二段凝灰岩储层孔隙多重分形特征OA北大核心CSTPCD

Tuff reservoirs,as a type of tight oil and gas reservoir,are significantly influenced by their micro and nano-pores in terms of hydrocarbon storage.To understand the pore structure and heterogeneity characteristics of tuff reservoirs in the Perm-ian Section 2 Feng in Hashan area,Junggar Basin,six tuff samples from Well Ha 11 in Hashan area were selected.These samples underwent total organic carbon(TOC)content measurement,whole rock mineral composition analysis,and character-ization of pore structure through CO2 and N2 adsorption experiments.Using multifractal theory,the pore heterogeneity and con-nectivity were analyzed.The results show that the average TOC content of the tuff samples is 0.931%,and the mineral compo-nents are mainly feldspar,quartz,clay minerals,and dolomite.Micropores are mainly developed in the 0.33-0.38,0.50-0.68,and 0.72-0.86 nm pore size ranges,while meso-macropores are mainly developed in the 2.94-16.09 nm range.The generalized fractal dimension Dq decreases with increasing q,and the singular fractal spectrum shows a convex asymmetric parabola.The pores in tuff reservoirs have multifractal characteristics.Micropores(0-2 nm)have smaller width of the singular spectrum(Δα)values and larger Hurst index(H)values,while meso-macropores(2-100 nm)have larger Δα values and smaller Hurst index(H)values,indicating that micropores have better homogeneity and connectivity.The heterogeneity of meso-macropores is affected by the pore volume.With the increase in pore volume,pore heterogeneity increases,and connectivity decreases.TOC content and mineral composition have different effects on pore heterogeneity and connectivity.An increase in TOC content improves the connectivity of meso-macropores.An increase in plagioclase content increases the heterogeneity of meso-macropores.An increase in clay mineral content increases the heterogeneity of micropores,while an increase in dolomite and calcite content reduces the heterogeneity of meso-macropores.