Pore Structure and Wettability of Lacustrine Shale With Carbonate Interlayers in Dongying Depression, Bohai Bay Basin, East China

Shale samples with carbonate interlayers have attracted more and attention in shale oil exploration of lacustrine China, the characterization pore structure wettability these shales are significant to study shale-oil enrichment effective exploitation. In this work, by examining six Shahejie Formation East characteristics characterized means thin section petrography; X-ray diffraction mineralogy; total organic carbon (TOC) analyses; scanning electron microscopy (SEM) imaging; air-liquid contact angle for wettability; as well N 2 physisorption, mercury intrusion porosimetry, nuclear magnetic resonance (NMR) structure. The results show that main mineral contents (with an average 51.4%) clay minerals (mainly mixed-layer illite-smectite). TOC content is 2.90%, there a strong correlation between dolomite content. addition, obvious layered observed SEM methods. pores below 200 nm ink-bottle shapes obviously smaller than those marine shale, throats mainly 50 nm; however, also some micrometer-sized cracks. droplet measurement shows lipophilic, while moderately hydrophilic, at millimeter observational scales. NMR T2 spectra water- oil-saturated feature three peak characteristics, size-associated can be divided into stages: water-wet (0.01–1 ms), oil-wet (1–40 mixed-wet (>40 ms) terms relaxation time T spectrum. proportion second (P2) dodecane-saturated directly proportional content, relationship P2 composition consistent water-saturated samples.