庆城油田成藏条件及勘探开发关键技术

2019年中国石油长庆油田公司在鄂尔多斯盆地中生界延长组长7油层组烃源岩层系内发现了中国最大的页岩油田——庆城油田,新增探明地质储量为3.58×10⁸t、预测地质储量为6.93×10⁸t,合计为10.51×10⁸t,实现了长7油层组页岩油勘探的历史性突破。近年来,围绕生油层内是否发育甜点区、能否形成工业产能和能否实现规模效益开发等关键难题,中国石油长庆油田公司通过持续深化成藏地质研究和不断探索关键配套技术,实现了烃源岩内油藏勘探的一系列理论认识创新和技术突破。研究结果表明,长7油层组中页岩油的成藏主要受以下因素控制:①广覆式细粒沉积组合具有整体生烃的特征,其中,黑色页岩和暗色泥岩等湖相优质烃源岩奠定了页岩油形成的物质基础;②泥页岩层系所夹持的砂质沉积物为勘探甜点段,而砂体组合的类型主要受控于湖底地形;③微米孔隙和纳米喉道的互补使得储层具有较好的储集性能;④高强度的源内充注形成了具有高含油饱和度、高气油比的油藏。这4个因素的有效组合是鄂尔多斯盆地长7油层组页岩油形成规模富集的关键。目前,通过创新关键配套技术,打造页岩油勘探...

Accumulation conditions and key exploration and development technologies in Q ingcheng oilfield

In 2019, PetroChina Changqing Oilfield Company discovered the Qingcheng oilfield, China's largest shale oilfield, in the source beds of Chang 7 oil layer of Mesozoic Yanchang Formation in Ordos Basin, forming 3.58×10⁸t of newly proven geological reserves and 6.93×10⁸t of predicted geological reserves, 10.51×10⁸t in total, and achieving a historic breakthrough in shale oil exploration in Chang 7 oil layer. In recent years, concentrating on the key challenges including whether sweet spot can be developed in source beds, whether industrial capacity can be formed and whether efficient development can be realized in a large scale, PetroChina Changqing Oilfield Company has achieved a series of theoretical understanding innovations and technological breakthroughs during reservoir exploration in source rocks by deepening the study of hydrocarbon accumulation mechanism and continuously exploring key supporting technologies. The research results show that shale oil accumulation in Chang 7 oil layer is mainly controlled by the following factors. First, the broad fine-grained sedimentary combination is characterized by hydrocarbon generation in the whole reservoirs, of which the lacustrine high-quality source rocks such as black shale and dark mudstone lay the material base for the formation of shale oil. Second, the sandy deposits sandwiched by shale beds are sweet spots for exploration, and the combination types of sand bodies are mainly controlled by the lakebed landform. Third, the complementarity of microscale pores and nanoscale throats results in good reservoir properties. Fourth, the high-intensity hydrocarbon charging in the source rocks has formed reservoirs with high oil saturation and gas-oil ratio. The effective combination of the above factors is the key to the large-scale enrichment of shale oil in Chang 7 oil layer of Ordos Basin. Currently, a substantial breakthrough in large-scale exploration and development of shale oil has been made by innovating key supporting technologies and creating powerful tools. The application of logging-seismic combination technology in loess tablelands has greatly improved the quality of three-dimensional seismic data, which can effectively guide the prediction of sandy sweet spots. The "three-quality" logging technology can be used to evaluate geological and engineering sweet spots. The partitioned volume fracturing of long horizontal wells can further increase single well production. The initial oil production of a single well is increased from 10 t/d to more than 18 t/d. The exploration breakthrough in the source reservoir of Chang 7 oil layer represented by Qingcheng oilfield provides an important resource foundation for the second-time accelerated development of PetroChina Changqing Oilfield Company. It is estimated that by 2023, the oil production from the shale beds of Chang 7 oil layer can reach 300×10⁴t and 500×10⁴t in 2025.