Revisiting Controls on Shale Oil Accumulation in Saline Lacustrine Basins: The Permian Lucaogou Formation Mixed Rocks, Junggar Basin

Figure 8

NMR spectra of the Lucaogou Formation, Jimusar Sag. (a) Well J10025, 3673.42 m, dolomitic mudstone with abundant organic matter and obvious dolomitization. Nanoscale pores (<1 μm) are present with a pore size of 1–100 nm. (b) Well J10025, 3487.21 m, well-sorted dolomitic siltstone containing rounded minerals. Intergranular pores are completely cemented by calcites and dolomites. The strong compaction and cementation have resulted in an extremely small pore size (i.e., nanopores; <1 μm), with the main pore size range being 1–40 nm. (c) Well J10025, 3537.1 m, dolomitic siltstone with evenly distributed dolomite, feldspar, and quartz. The main pore size range is 0.001–10 μm. (d) Well J10025, 3506.1 m, mudstone containing a large carbonate vein and cracks. The pore size range is relatively large and consists of nano-micropores with a main pore size range of 0.001–10 μm. (e) Well J10025, 3559.31 m, laminated dolomitic siltstone containing abundant organic matter and cemented by dolomite and calcite. Micron-sized pores (>1 μm) occur, and the main pore size range is 1–10000 nm. (f) Well J10025, 3680.99 m, laminated marlstone containing abundant, small, spherical particles of organic matter. Dissolution and intergranular pores are well developed. Micron-scale pores are present (>1 μm), and the main pore size ranges are 1–800 nm and 2–15 μm. (g) Well J10025, 3531.33 m, silty dolomite with bioclastic layers. Dissolution pores that are micron-sized (>1 μm) are present, and the main pore size range is 0.001–12 μm. (h) Well J10025, 3603.07 m, residual oolitic-micritic dolomite. Most of the concentrically laminated oolites have been dolomitized. Dissolution pores are micron-sized (>1 μm), and the main pore size range is 0.001–3 μm. (i) Well J10025, 3608.16 m, silty argillaceous dolomite with lumpy organic matter (fungi-algae lumps). Crustacean-like calcite cement has formed on the surfaces of the fungi-algae. Nano-micron pores are developed, and the main pore size ranges are 1–1000 nm and 1.5–40 μm. (j) Well J10025, 3623.82 m, argillaceous siltstone that contains organic-rich layers and oriented silt-sized minerals. Nano-micron pores occur, with main pore size ranges of 1–1000 nm, 1.5–40 μm, and 100–200 μm. (k) Well J10025, 3700.88 m, laminated silty dolomitic mudstone. Nano-micron pores have main pore size ranges of 1–50 nm, 150–800 μm, and 1–10 μm. (l) Well J10025, 3713.18 m, mudstone containing large mineral veins and crystalline pyrite. Nano-micron pores have main pore sizes ranges of 1–60 nm and 0.1–200 μm.

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