关键词: 鄂尔多斯盆地, 页岩油, 延长组, 长7段, 勘探开发, 新进展

Abstract: As an important replacement resource, shale oil is a major exploration field widely concerned at home and abroad. The long-term exploration and development practice enabled to make significant breakthrough and progress in the exploration, development and research of shale oil in the seventh member of Yanchang Formation (Chang 7 member) in Ordos Basin: (1) On the basis of exploration breakthrough in the interlayered type shale oil and discovery of the first integral one-billion-ton level Qingcheng Oilfield, the large-scale and benefit development has been achieved, and a million-ton level national shale oil development demonstration zone has been constructed. (2) In the exploration of the laminated type shale oil, four types of laminated type have been classified of the fine-grained sedimentary complex for the first time, i.e., sandy lamina, tuffaceous lamina, high TOC argillaceous lamina, and medium-low TOC argillaceous lamina. The combination of sandy lamina and medium-low TOC argillaceous lamina is the optimal “sweet spot” interval of the laminated shale oil by evaluating their development scale, reservoir performance, oil-bearing property, movability, and crude oil properties. For the sweet spot interval, new logging evaluation methods such as M-N cross plot are used to finely interpret the complex lithology, and the directional perforation and cross-layer stereoscopic fracturing technology enable to achieve the spatial communication of sweet spots around the wellbore in horizontal section, forming technologies for the effective identification, prediction of sweet spots and reconstruction of the laminated type shale oil, and achieving a major breakthrough in risk exploration, with the primarily submitted predicted shale oil reserves of 2.05×10⁸ t. (3) The laminar type shale oil is subdivided into two categories. The medium-high maturity organic shale can be developed by horizontal well, and relatively high TOC (4%-14%) and high S₁ content are key indicators for screening favorable sweet spots. While the medium-low maturity organic shale is the most favorable target for in-situ transformation research. The strategic breakthrough has been made in the exploration of continental shale oil in Chang 7 member in Ordos Basin, which is a milestone in China’s petroleum exploration and development history, but it still faces great challenges. For example, the large-scale and benefit development has been achieved of the interlayered type shale oil, but further research should be conducted on the prediction of sweet spots, production increase and efficiency improvement, and enhanced oil recovery. The laminated type shale oil is facing more challenges and greater difficulty in benefit utilization due to the completely different sedimentary settings, lithologic combination, reservoir space, and engineering quality from the interlayered type shale oil. Therefore, by focusing on the reserve quality and oil movability, hydrocarbon accumulation law should continuously be studied and the research on supporting technology should be strengthened. While for the laminar type shale oil with relative low level of exploration and understanding, the theoretical research and pilot test should steadily be promoted.