重庆及其周缘地区下古生界页岩样品核磁共振实验研究

发布时间：2018-08-22 18:22

【摘要】：重庆及其周缘地区下古生界下寒武统筇竹寺组、上奥陶统五峰组—下志留统龙马溪组页岩具备页岩气形成的有利地质条件,是四川盆地主要的气源岩之一。探索该区页岩核磁共振的有效实验方法,可以为页岩气的勘探开发提供技术支持;研究该区页岩的孔隙度、渗透率等物理性质,并辅以理论分析、岩石物理实验与分析,可以更好的分析评价该区目标储层页岩的开发潜力。本文基于页岩核磁共振原理,选取研究区代表性样品,开展实验研究。首先,设置不同实验参数开展页岩核磁共振实验,分析实验参数对核磁共振测量结果的影响,研究核磁共振实验有效参数的选取方法。然后,对研究区页岩进行核磁共振测量,定量计算页岩的孔隙度、渗透率等物性参数,并结合常规岩心分析资料,通过数值拟合确定核磁渗透率模型的待定系数C。最后,构建页岩核磁共振T2谱分布,将研究区页岩进行分型分类,定性评价页岩孔隙结构、孔径分布等特征,建立研究区页岩核磁共振解释方法。本文通过页岩样品核磁共振实验,确定以下参数:回波间隔TE=0.11ms,回波个数NECH=4096,采样次数NS=8,等待时间TW=6000ms适合研究区页岩核磁共振测试;根据页岩岩样孔径分布中峰值点T2值的分布及各类孔隙的含量百分比,将研究区页岩分为3型:过渡孔—微孔型、过渡孔—中孔型、中孔—过渡孔型;根据各型页岩不同层位岩样横向弛豫时间T2谱形态的差异,将各型页岩T2谱分为3类:单峰态T2谱、双峰态T2谱、三峰态T2谱。分析研究发现:研究区下志留统龙马溪组(LMX)页岩孔渗条件最好,下寒武统筇竹寺组(QZS)次之,奥陶统五峰组(WF)较差。通过实验及数值拟合确定了研究区页岩样品核磁共振T2截止值为2ms,核磁渗透率模型待定系数C=30.03,且Coates模型在研究区有更好的适用性。页岩样品核磁共振孔隙度与密度、渗透率与峰值点T2值均有较好的相关性,可建立计算模型,便于快速获取研究区页岩孔隙度、渗透率等物性参数。
[Abstract]:The shales of Lower Cambrian Qiongzhusi formation and Upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Chongqing and its surrounding areas have favorable geological conditions for shale gas formation and are one of the main gas source rocks in Sichuan Basin. Exploring the effective experimental method of shale nuclear magnetic resonance in this area can provide technical support for the exploration and development of shale gas, study the physical properties of shale porosity and permeability, and be supplemented by theoretical analysis, rock physics experiment and analysis. It can better analyze and evaluate the development potential of the target reservoir shale in this area. Based on the theory of shale nuclear magnetic resonance (NMR), the representative samples of the study area were selected and the experimental study was carried out. Firstly, the shale nuclear magnetic resonance (NMR) experiment was carried out with different experimental parameters. The influence of the experimental parameters on the nuclear magnetic resonance (NMR) measurement results was analyzed, and the method of selecting the effective parameters of the NMR experiment was studied. Then, the nuclear magnetic resonance (NMR) measurements were carried out to quantitatively calculate the porosity and permeability of shale, and combined with the conventional core analysis data, the undetermined coefficient C of the model was determined by numerical fitting. Finally, the NMR T2 spectrum distribution of shale was constructed, the shale in the study area was classified, the pore structure and pore size distribution of shale were evaluated qualitatively, and the interpretation method of nuclear magnetic resonance was established. In this paper, the following parameters are determined by nuclear magnetic resonance (NMR) experiments of shale samples: the echo interval is 0.11ms, the number of echo is NECH 4096, the sampling number is NS8, and the waiting time TW=6000ms is suitable for shale nuclear magnetic resonance testing in the study area. According to the distribution of T _ 2 value of peak point and percentage of various pores in the pore distribution of shale samples, the shale in the study area is divided into three types: transitional pore-micropore type, transitional pore-mesoporous type, mesoporous-transitional pore type; According to the difference of transverse relaxation time T 2 spectra of different types of shale samples, the T 2 spectra of different types of shale are classified into three types: single peak T 2, double peak T 2 and three peak T 2. It is found that the (LMX) shale porosity and permeability conditions are the best in the lower Silurian Longmaxi formation, followed by the lower Cambrian Qiongzhusi formation (QZS) and the Ordovician Wufeng formation. The T _ 2 cut-off value of nuclear magnetic resonance (NMR) for shale samples in the study area is determined to be 2msand the undetermined coefficient C _ (30.03) of the nuclear magnetic permeability model is determined by experiments and numerical fitting. The Coates model is more suitable for the study area. The nuclear magnetic resonance porosity and density, permeability and peak T _ 2 value of shale samples are all well correlated, so the calculation model can be established to obtain the physical parameters of shale porosity and permeability in the study area quickly.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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