LAUSR

Tight sandstone samples from the Gao 3 and Gao 4 members of Gaotaizi reservoir in Qijia area of the northern Songliao Basin were targeted as the main research objects in this paper. Through micro/nano CT technology and auto skeleton module and connectivity module in avizo software, three-dimensional models for the micro pore structure of Gaotaizi tight sandstone in the research area were constructed. The experimental results demonstrate that types of reservoir space include intergranular dissolution pores, intragranular dissolution pores, and micro-fractures, indicating remarkable microscopic heterogeneity with characteristics of a continuous distribution in a micronano scale. Under the micro scale, different physical property and sedimentary microfacies of tight reservoir show various pore structure characteristics in three-dimensional space, with the primary front of pore throats mainly distributed in 0.6~1.5 μm. Under the nanoscale, micro heterogeneity is remarkable, with the primary front of pore throats distributed in 40~100 nm. In addition, the nanopore distribution pattern in three-dimensional space mainly includes the nanopores in the granules and the nanofractures, of which the latter type plays a crucial role in connecting nanopores and migration of nano oil and gas migration; at the same time, this paper verify the digital core experimental results by using MICP technology. With the further development of big data technology and deep learning technology, three-dimensional digital core technology based on micro/nano CT technology will become an important technology applied in the exploration and development of unconventional oil and gas.