广泛连续型致密砂岩气藏成因机制与预测方法

Oil and gas exploration shows that geological characteristics of continuous-type tight-sand gas reservoirs are significantly different from conventional oil and gas reservoirs. Tight-sand gas is the most realistic option among unconventional gas at present. Understanding the genetic mechanism of tight-sand gas reservoirs and their prediction methods is of great significance to improve the hydrocarbon accumulation theory, to guide the exploration of tight-sand gas reservoirs, and to maintain the balance between gas supply and gas demand. Under the auspices of the National "973" projects and petrochemical joint fund project, the project will conduct the study of genetic mechanism and prediction method of continuous-type tight-sand gas in upper-paleozoic of the Ordos Basin which has most abundance of tight-sand gas resources, the best exploration effectiveness and the most data. Focusing on the study of dynamic boundary of continuous-type tight-sand gas accumulation, the project aims to reveal the genetic mechanism and distribution pattern of continuous-type tight-sand gas reservoirs and to establish the quantitative relationship between tight-sand gas reservoirs and their main controlling factors within different fluid dynamic field. Finally, the prediction method of enrichment is developed to provide theoretical and methodological guidance for the prediction and evaluation of exploration targets. Through this project, we are looking forward to understanding the genetic mechanism of continuous-type tight-sand gas reservoirs, to establishing their prediction method, and to clarifying residual resources potential of study area. Besides, 3-5 SCI papers are expected to be published in high-level journals.

油气勘探实践表明，连续型致密砂岩气藏具有明显区别于常规油气藏的地质特征。致密砂岩气是现阶段非常规天然气领域内最现实的选择。搞清致密砂岩气藏的成因机制与预测方法应用对完善油气成藏理论、指导致密砂岩气勘探、维持我国天然气供需平衡具有重要意义。本项目拟在石油化工联合基金项目资助下，选择中国致密砂岩气资源最丰富、勘探成效最好、积累资料和成果最多的鄂尔多斯盆地上古生界开展连续型致密砂岩气藏成因机制和预测方法研究。重点研究连续型致密砂岩气成藏的动力学边界，揭示连续型致密砂岩气藏的成因机制与分布模式，建立不同流体动力场内的致密砂岩气藏与主控因素之间的定量关系式，形成富集目标预测方法，为勘探目标预测与评价提供理论与方法指导。期待通过本项目的研究，解决连续型致密砂岩气的成因机制，建立致密砂岩气预测方法，搞清研究区剩余资源潜力，在国内外高水平杂志上发表3-5篇SCI论文。

含油气盆地存在浮力作用下限和油气成藏底限两大动力学边界，将沉积盆地划分为自由流体动力场、局限流体动力场和束缚流体动力场，局限流体动力场控制着广泛连续型致密砂岩油气藏的有利发育领域。本次研究通过开展物理模拟实验，揭示了浮力作用下限和油气成藏底限形成的动力学机制，以及广泛连续型致密砂岩油气藏形成过程特征与压力转换机制。划分了广泛连续型致密砂岩油气藏类型，总结了不同类型致密砂岩油气藏成因机制与主控因素，建立了广泛连续型致密砂岩油气藏有利发育领域、有利分布区带、有利含气目标的定量预测与评价方法。以鄂尔多斯盆地为重点研究区，对米脂气藏、苏里格气藏、榆林气藏进行了详细解剖，总结了鄂尔多斯盆地致密砂岩气藏分布地质特征、富集特征，建立了鄂尔多斯盆地上古生界广泛连续型致密砂岩气成藏模式。通过多种方法确定了研究区上古生界浮力成藏下限和油气成藏底限，预测鄂尔多斯盆地上古生界致密砂岩藏分布范围为2000m~6100m；通过功能要素组合控藏模式预测了盒8段致密砂岩气藏有利分布区带；利用相-势-源耦合方法定量预测了苏里格地区盒8段致密砂岩气藏有利目标，优选出两大有利目标区块。