Abstract:
The Maiduoshan coal mine on the western edge of the Ordos Basin features a total of 19 coal seams. Most of these seams exhibit unstable spatial distribution, and the area is characterized by complex structures, including folds and numerous faults, making coal seam correlation challenging and a persistent issue in geological exploration over the years. By utilizing drilling core geological logging, well logging, 3D seismic, and other techniques, and through the integration of well-seismic data with high-resolution sequence stratigraphy division, sedimentary microfacies identification, special stratigraphic sequence identification, establishment of special geological markers, and theoretical research on structure-controlled stratigraphy, a coal seam correlation scheme for the Maiduoshan Coal Mine on the western edge of the Ordos Basin has been determined. This scheme divides the area into three base-level cycles (LSQ1, LSQ2, and LSQ3). The relatively stable thick coal seams are distributed at the top of the base-level cycles and the top of the ascending half-cycle of the base level. The LSQ1 coal seams are mostly sandwiched between normal cycles, the LSQ2 coal seams are mostly sandwiched between siltstones, and the LSQ3 coal seams are mostly sandwiched between sandstones. The thick-bedded planar stratification sandstones at the bottom of LSQ1, the thick-bedded massive stratification sandstones at the top of LSQ3, the relatively thick Coal Seam 18, and the thick black mudstones above Coal Seam 12 are all typical correlation markers. At the anticlinal locations, the coal seams are laterally offset and fractured. The flower-like structures in the anticlinal areas show a steep drop in coal seam depth from bottom to top, and the thrust faults cause duplication of Coal Seam 18 at the anticlinal locations. The thrust faults also lead to an upward bending of the strata, resulting in reduced coal seam thickness, and an increase in the dip angle of the strata, causing changes in the dip direction on both sides of the flower-like structures. The comprehensive coal seam correlation method provides a new approach for coal seam correlation in the area, improves the accuracy of coal seam correlation, and provides a theoretical basis for coalfield exploration and coal mine production.