| 北黄海盆地下白垩统致密砂岩储层特征及成因 |
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| 引用本文： | 王改云,刘金萍,简晓玲,王后金,杜民,万晓明.北黄海盆地下白垩统致密砂岩储层特征及成因[J].地球科学,2016,41(3):523-532. |
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| 作者姓名： | 王改云 刘金萍 简晓玲 王后金 杜民 万晓明 |
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| 作者单位： | 广州海洋地质调查局国土资源部海底矿产资源重点实验室，广东广州 510075 |
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| 基金项目： | 国土资源部海底矿产资源重点实验室开放基金KLMMR-2014-A-10国家自然科学基金项目41302100 |
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| 摘 要： | 北黄海盆地是我国近海勘探及研究程度均较低的中新生代叠合断陷盆地，下白垩统砂岩储层是主要的勘探目的层段，储层致密是制约该区油气勘探的“瓶颈”之一.通过岩心观察、薄片分析、扫描电镜观测、压汞分析、物性统计等研究，对北黄海盆地东部坳陷下白垩统的储层特征进行了研究，从沉积、成岩、埋藏史等方面对其致密化成因进行了探讨.结果表明，下白垩统储层以扇三角洲沉积为主，物性总体较差，属于特低孔特低渗的致密砂岩储层，储集空间主要有粒间溶孔、粒内溶孔、微裂缝等次生孔隙，属孔隙—裂缝双孔介质储层，孔隙结构复杂.该储层特征主要受沉积相带、成岩作用及埋藏史等因素控制，储层砂体以长石岩屑砂岩、岩屑长石砂岩为主，成分及结构成熟度中等，原始储层物性差，高含量的塑性岩屑不利于原生孔隙的保存，沉积物粒度决定微裂缝的发育程度.成岩作用起主导作用，受早期深埋—中期抬升剥蚀—晚期再次深埋的这一特定埋藏过程影响，早期强烈压实，后期石英自生加大、方解石胶结、自生矿物晶出等胶结作用导致储层整体致密.长石的溶蚀和粘土化促进了次生孔隙的形成，但烃类充注时间晚、酸性流体活动弱，溶蚀作用受到抑制.后期构造作用产生的微裂隙则是改善储层物性的另一重要作用.
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| 关 键 词： | 北黄海盆地 下白垩统 致密砂岩储层 沉积学 |
| 收稿时间： | 2015-11-12 |
Characteristics and Genetic Mechanism of Tight Sandstone Reservoirs of Lower Crataceous in North Yellow Sea Basin |
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| Abstract: | North Yellow Sea Basin is a typical Meso-Cenozoic superimposed fault basin, which has undergone few exploration and research in the offshore of China. The sandstone reservoirs of Lower Crataceous are the main exploration targets, but reservoirs tightness is the "bottleneck" which restricts the exploration activity in North Yellow Sea Basin. By core observation, thin section analysis, scanning scanning electron microscope observation, mercury penetration analysis, porosity and permeability statistics, the reservoirs characteristics of Lower Crataceous in eastern depression in North Yellow Sea Basin were researched in this paper. According to deposition, diagenesis, burial history, and so on, the origin mechanism of tightness of the reservoirs was analyzed. The results show that the sedimentary facies type of reservoirs is mainly fan delta. Reservoir physical properties are poor, belonging to extra-low porosity and extra-low permeability tight sandstone reservoirs. Main reservoir spaces are corrosion pores between grains or in grains and a few micro-fractures. The reservoir belongs to dual porosity reservoirs with pores and fractures, and the pore structure is complex. The reservoirs characteristics are controlled by sedimentary facies zone, diagenesis and burial history. The reservoir lithology is mainly feldspathic lithic sandstone and lithic feldspathic sandstone, which have medium textural maturity and compositional maturity, resulting in poor initial reservoir quality. The high content of plastic debris is not conducive to the preservation of primary porosity. The grain size of sediment affects the development of micro-fractures. The diagenesis predominates in the reservoirs tightness. The diagenetic process is decided by the burial history, which includes early deep burial, middle uplift denudation, and later deep burial. The reservoirs tightness is mainly caused by intense compaction in early phase and cementation in later phase, such as quartz increase, calcite cementation, and spontaneous mineral crystal. Feldspar corrosion and inverting kaolinite facilitate the formation of secondary porosity. The late of hydrocarbon injection causes the weak acid fluid activity, which inhibits dissolution. Fractures without displacement in later phase improve partly the reservoir property. |
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