鄂尔多斯盆地延长探区低渗致密油气成藏理论进展及勘探实践

延长石油集团在鄂尔多斯盆地大力推动石油、天然气、页岩气勘探开发理论研究和技术攻关，多类型资源协同发展，取得显著效果。在石油勘探方面，提出延长组特低渗石油“交替式”成藏理论认识，建立盆地中生界多期差异性成藏新模式，近10年特低渗石油年均探明地质储量超1×10⁸ t。建立细粒沉积风暴、地震等控砂理论，以及甜点预测方法，致密油累计探明地质储量2.1×10⁸ t。针对致密气田砂体成因机理不明、天然气运聚成藏规律不清等主要难题，揭示了“浅水环境岸线频繁迁移控砂”机制，建立了致密砂岩气优质储层成储模式，明确纯石英砂岩和富石英低塑性颗粒岩屑砂岩是致密气分布的“甜点”,形成了基于多要素、全过程天然气运聚模拟的目标优选技术。经勘探实践，发现了延安气田，累计探明天然气地质储量7 635×10⁸ m³。页岩气方面，提出陆相页岩气“三元”成藏富集地质理论的创新认识，认为湖相优质页岩是陆相页岩气富集高产的物质基础，多类型、跨尺度的复杂孔隙网络决定页岩气赋存条件，厚层页岩自封闭能力及高压是保存的关键，实现陆相页岩气产量突破。未...

Low permeability tight oil and gas in Yanchang area,Ordos Basin: Advances in accumulation theory and exploration practice

Petroleum resources (oil, natural gas, shale gas) exploration and development in the Ordos Basin has achieved remarkable results owing to the coordinated resources development as well as theoretical and technical researches promoted by the Shaanxi Yanchang Petroleum (Group) Co., Ltd. In petroleum exploration, a “alternate accumulation of ultra-low permeability oil” theory is proposed, and a new model for Mesozoic multi-stage differential accumulation is establishment, which leads to the discovery of ultra-low permeability oil reserves exceeding 1×10⁸ t per year for the last 10 years. In tight oil discovery, the “sand control by storm and earthquake” theory is proposed for fine-grained sedimentary areas, along with a “sweet spot” prediction method, which leads to the discovery of tight oil reserves totaling 2.1×10⁸ t. In tight gas exploration, the genetic mechanism of sand bodies in tight gas fields and the law of natural gas migration and accumulation are unclear. To overcome this problem a new theory is proposed which considers sand-body distribution is controlled by frequent shoreline migration in shallow water environment, and a formation model for high-quality tight sandstone gas reservoir is established. It is found that pure quartz sandstone and quartz-rich low-plastic granular lithic sandstone are tight-gas “sweet spots”, and a target optimization technique is developed based on multi-element, whole-process natural gas migration and accumulation simulation, which leads to the discovery of the Yan’an gas field with 7635×10⁸ m³ natural gas in reserves. In shale gas exploration, a “ternary accumulation and enrichment of continental shale gas” theory is proposed, which considers that the high-quality lacustrine shale is the material basis for shale gas enrichment and high production, the multi-type, multi-scale complex pore network determines the occurrence conditions of shale gas, and the self-sealing ability and high pressure of thick shale are the keys to gas storage. In the future, the Yanchang Petroleum Group will continue to adhere to the strategy “stabilize oil production, boost gas production, strengthen unconventional resources development”, and ensure sustainable enterprise development by promoting “integrated geological engineering” in resources exploration and development.