| 摘要: |
| 以伊拉克M油田Mishrif组生物碎屑灰岩为例,基于岩心和铸体薄片资料,研究生物扰动对沉积环境的选择性、生物扰动程度的表征方法,充填物的形成条件和控制因素及生物扰动对储层物性的改造机制。结果表明:M油田Mishrif组为缓坡-弱镶边台地沉积环境,生物扰动倾向于在低能安静的局限水体环境中发育,其中潟湖环境中生物扰动现象最为普遍;根据扰动面积与岩心切面面积比值,以20%、50%和80%为界,辅以描述扰动连通性的术语,将生物扰动划分为Ⅰ级斑状扰动、Ⅱ级纹层状扰动、Ⅲ级迷宫状扰动和Ⅳ级层状扰动4个等级;生物扰动通道中充填物包括同生碎屑颗粒、白云石和方解石,其中同生碎屑颗粒为物理成因,受沉积作用控制,而白云石和方解石为后期成岩作用产物。白云石成因机制复杂、晶体形态多样,其中微晶离散状白云石对储层物性影响较小,自形细晶白云石有利于改造储层物性,而自形—半自形镶嵌状白云石降低储层物性;综合沉积物岩石学特征、生物扰动程度、充填物质差异及对储层物性影响等因素,建立M油田Mishrif组生物扰动模式;沉积环境决定了生物扰动的底质和保存程度,生物扰动程度反映了储层改造强度,后期充填物质和成岩作用控制了储层改造性质,生物扰动强度越大,自形细晶白云石发育程度越高,溶蚀作用越强,储层物性越好。 |
| 关键词: 生物扰动 Mishrif组 白云石 扰动模式 |
| DOI：10.3969/j.issn.1673-5005.2021.02.003 |
| 分类号::TE 122.2 |
| 文献标识码:A |
| 基金项目: |
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| Bioturbation of Mishrif Formation in M Oilfield, Iraq |
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LI Fengfeng1, WANG Zhenbiao1, GUO Rui1, LIU Lifeng1, YU Yichang1, SONG Shiqi2
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(1.Research Institute of Petroleum Exploration & Development, Beijing 100083,China;2.College of Geoscience in China University of Petroleum (Beijing), Beijing 102249, China)
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| Abstract: |
| Taking the bioclastic limestone of Mishrif Formation in M Oilfield, Iraq as an example, the environment preference, the infilling genesis and controlling factors, and the mechanism of bioturbation were studied. The results show that the research area is a ramp with weak rimmed platform. Bioturbation is more inclined to develope in low-energy environment,especially in the lagoon. According to the ratio of the bioturbated area to the core section area, four grades are defined , which are separated by 20%, 50% and 80% connectivity. The four bioturbation grades are:Grade Ⅰ porphyritic, Grade Ⅱ laminated, Grade Ⅲ labyrinth and Grade Ⅳ thick layers. There are three kinds of filling materials, syngenetic clastic, dolomite and calcite in the bioturbation channel. The clastic is the physical genesis and is controlled by sedimentation, while dolomite and calcite are the products of late diagenesis.Dolomite can bedivided into the microcrystalline discrete dolomite, the euhedral fine-grained dolomite and the euhedral-semieuhedral mosaic dolomite. Among them, the microcrystalline discrete dolomite has little effect on reservoir physical properties, and the euhedral fine-grained dolomite is beneficial to improve physical properties, while the euhedral-semi euhedral mosaic dolomite reduces physical properties. The bioturbation mode of Mishrif Formation in Moilfield was established by combining petrology, degree of bioturbation, filling material and influences on physical properties. The sedimentary environment determines the substrate and preservation condition, the degree of bioturbation reflects the strength of reconstruction, and the filling material and diagenesis control the transformation properties. The greater the bioturbation intensity is, the more the euhedral fine-grained dolomite is, and the stronger the dissolution is, the better the reservoir properties are. |
| Key words: bioturbation Mishrif Formation dolomite bioturbation mode |
