致密混积岩储层孔喉网络体系成因机理与多尺度表征评价研究

Tight mixosedimentite has huge potential in oil and gas resources. However, its exploration and development are seriously restricted by complex characteristics of pore-throat network systems in reservoirs. Taking the tight mixosedimentite reservoir on the top of the Lower Ganchaigou Formation in the Tsaidam Basin as an example, this project grasps the formation mechanism of the pore-throat network systems and establishes the multiscale quantitative characterization method, which will promote not only the theoretical research of pore-throat network systems for complex lithology, but also the exploration and development of oil and gas in China. Classifying the lithology and lithofacies for tight mixosedimentite reservoir is constrained under the sequence stratigraphic framework and sedimentary microfacies. And on this basis, types and matching relations of pore-throats as well as their impacts on the macroscopic reservoir properties are further analyzed to establish the classification criterion of pore-throat network systems. And then, the controlling effects of diagenesis type, diagenesis intensity and diagenetic minerals distribution on the formation of pore-throat network systems in reservoirs are fully explained. According to the following multiscale characterization of pore-throat network systems from nanometre to decimeter by core experiment and well logging data, classification of pore-throat network systems are unfolded from point and line to plane, and the “sweet spot” of reservoirs are predicted through the distribution of pore-throat network systems. This research is expected to make innovative achievements in the aspects of classification, formation mechanism, well logging recognition and characterization of the pore-throat network systems for tight mixosedimentite reservoirs. 3 SCI papers are expected to be published. 1 patent and 1 software copyright are planned to apply.

致密混积岩油气资源潜力巨大，但储层内部孔喉网络体系特征复杂，严重制约了我国油气的勘探开发。课题以柴达木盆地下干柴沟组上段致密混积岩储层为例，以明确孔喉网络体系成因机理、建立多尺度定量表征方法为目标，推动复杂岩性孔喉网络体系的理论研究，同时促进我国油气的勘探开发。研究以层序格架和沉积微相约束下的致密混积岩储层岩性岩相分类为基础，深入分析孔喉类型、匹配关系及其对宏观物性的影响，建立孔喉网络体系分类标准，阐明成岩作用类型、强度和成岩矿物分布等对储层孔喉网络体系形成的控制作用。通过岩心实验和测井资料对储层孔喉网络体系进行由纳米至分米的多尺度表征，将孔喉网络体系分类由点到线至面展开，并根据孔喉网络体系分布规律对储层“甜点”进行预测。课题将在致密混积岩储层孔喉网络体系分类模式、成因机理和由微观到宏观的测井识别表征方面取得创新性成果，拟发表SCI论文3篇，申报专利和软件著作权各一项。

我国湖相混积岩储层蕴藏着十分丰富的油气资源，但由于储层致密、矿物组成复杂、储集空间类型多样和薄互层频繁的特点，造就了湖相混积岩具有十分复杂的孔喉网络体系，严重制约了油气的勘探开发。课题以柴达木盆地英西地区致密混积岩储层为例，以明确孔喉网络体系特征及成因机理、建立孔隙结构多尺度定量表征方法为目标，推动复杂岩性孔喉网络体系的理论研究，促进我国油气的勘探开发。通过自然科学基金面上项目近4年的攻关研究，该项目：1）归纳总结了柴达木盆地英西地区下干柴沟组上段湖相混积岩孔喉类型、大小、分布及连通性特征；2）建立了湖相致密混积岩孔喉网络体系微观尺度和测井宏观尺度分类评价标准及定量表征方法；3）明确了致密混积岩储层内部孔喉类型、配置关系及其对宏观物性的影响，建立了致密混积岩储层孔喉网络体系分类标准及命名方案；4）查明了不同岩性岩相约束下的成岩作用类型、成岩作用强度及成岩矿物对致密混积岩储层孔喉网络体系特征的影响；5）建立孔喉网络体系约束下的致密混积岩储层有效性评价和有利发育区带预测方法。该项目在致密混积岩储层孔喉网络体系分类标准、成因机理、由微观到宏观的测井识别表征方法、渗透率计算与储层有效性评价等方面取得了一系列创新性成果与认识，不仅深化了复杂岩性孔隙结构研究的理论基础，还对我国复杂岩性储层的油气勘探开发具有实际意义。