下扬子地区二叠系页岩储集物性及含气性地质模型

发布时间：2018-03-12 11:24

本文选题：下扬子地区　切入点：二叠系页岩　出处：《中国科学院研究生院(广州地球化学研究所)》2016年博士论文　论文类型：学位论文

【摘要】：南方下扬子地区富有机质二叠系页岩广泛发育,是未来页岩气勘探开发的潜在目标。然而,该套页岩的研究程度很低,尤其是缺乏孔隙结构与含气性方面的模型,页岩气资源潜力不落实,将严重影响勘探开发的进程。本论文主要对取自研究区内芜湖区块两口参数井(C1与H1)的二叠系页岩,系统的开展了有机地球化学特征、储集物性、吸附特征、含气性评价等方面的研究;结合热模拟样品,研究了孔隙结构的演化及影响因素。在此基础上,结合地质及储层参数,构建了二叠系页岩含气性地质模型,探讨了页岩气勘探开发潜力。本论文取得主要成果与认识如下:(1)本研究所选二叠系页岩样品TOC含量范围为0.6%-17.4%,平均为7.80%;成熟度高,镜质组反射率范围为2.34%-2.66%;有机质类型为III型干酪根。页岩孔隙度范围为0.98%-5.52%。随着TOC含量的增加,孔隙度呈现出先增加后降低的趋势,转折点在TOC为12%左右。高TOC含量(12%)页岩孔隙度降低与较大有机孔隙的压实作用有关。(2)有机质含量不同将对页岩孔隙发育具有重要影响。二叠系页岩样品微孔的孔容、比表面积,介孔的比表面积与TOC含量呈现正相关,而对于高TOC含量的样品(12%),介孔、大孔孔容与TOC含量呈现负相关,认为压实作用主要是抑制有机质中的大孔与较大的介孔,并使得微孔更加发育。(3)页岩中残余可溶有机质对低熟页岩孔隙结构的表征具有重要影响。残余可溶有机质主要赋存于微孔及较小的介孔中,同时还受成熟度水平的制约。较低成熟度页岩样品的残余可溶有机质主要赋存于微孔及小于5nm的介孔中,而中等成熟度页岩样品的残余可溶有机质主要赋存于微孔及小于20nm的介孔中。(4)二叠系页岩的吸附参数(最大过剩吸附量、最大绝对吸附量、吸附相密度)主要受TOC含量与吸附温度的制约。与TOC含量呈正相关,与吸附温度呈负相关。构建了研究区内二叠系页岩储层的基于不同温度条件下页岩高压吸附参数、储层参数及地层温度压力梯度的含气性地质模型。随着储层埋藏深度的增加,页岩过剩吸附气量和绝对吸附气量都表现为先增加后降低的演化趋势,最大值分别出现在400-700m与900-1400m左右,而页岩游离气含量一直呈现出增加的趋势。(5)以研究区块为例,建立了不同TOC含量页岩的含气性模型。TOC含量影响页岩的储气能力和页岩气的赋存状态。较低TOC含量(4%)的页岩,吸附气和游离气含量都低,储气潜力较差;过高TOC含量(12%)的页岩孔隙度较低,能为游离气提供有效储存空间能力较低,游离气所占比例较低,影响页岩气勘探开发。认为深层超压区将是下扬子地区二叠系页岩气有利的勘探开发方向。
[Abstract]:The widespread development of organic matter rich Permian shale in the southern Yangtze region is a potential target for shale gas exploration and development in the future. However, the research level of this set of shale is very low, especially the lack of models for pore structure and gas-bearing properties. If the potential of shale gas resources is not realized, the process of exploration and development will be seriously affected. In this paper, the organic geochemical characteristics and reservoir properties of Permian shale derived from two parameter wells of Wuhu block, Wuhu block, are systematically carried out. On the basis of the study of adsorption characteristics and gas content evaluation, the evolution of pore structure and the influencing factors, combined with thermal simulated samples, a geological model of Permian shale gas-bearing property is constructed. The potential of shale gas exploration and exploitation is discussed in this paper. The main achievements and understandings in this paper are as follows: (1) the TOC content of Permian shale samples selected in this study ranges from 0.6 to 17.4, with an average of 7.80 and a high maturity. The vitrinite reflectance ranges from 2.34 to 2.66; the organic matter type is III kerogen; the shale porosity ranges from 0.98 to 5.52. With the increase of TOC content, the porosity increases first and then decreases. The turning point is that TOC is about 12%. The decrease of shale porosity is related to the compaction of larger organic pores. The difference of organic matter content will have an important effect on the development of shale pores. The pore volume and specific surface area of Permian shale samples are studied. The specific surface area of mesoporous cells was positively correlated with the content of TOC, while that of samples with high TOC content was negatively correlated with the content of TOC. It was considered that compaction was mainly due to the inhibition of macropores and larger mesoporous cells in organic matter. The residual soluble organic matter in shale plays an important role in the characterization of pore structure of low-mature shale. The residual soluble organic matter mainly occurs in micropores and small mesoporous pores. At the same time, the residual soluble organic matter of the low maturity shale samples is mainly located in micropores and mesoporous samples with less than 5 nm. However, the residual soluble organic matter of the medium maturity shale samples mainly occurs in micropores and mesoporous mesoporous areas less than 20nm. The adsorption parameters of Permian shale (maximum excess adsorption capacity, maximum absolute adsorption capacity, maximum excess adsorption capacity and absolute adsorption capacity) are found in the medium maturity shale samples. The adsorption phase density is mainly restricted by TOC content and adsorption temperature, and is positively correlated with TOC content and negatively correlated with adsorption temperature. The shale high pressure adsorption parameters of Permian shale reservoir in the study area are constructed based on different temperature conditions. The gas bearing geological model of reservoir parameters and formation temperature and pressure gradient. With the increase of reservoir burial depth, the excess gas adsorption capacity and absolute adsorption gas capacity of shale show an evolutionary trend of first increasing and then decreasing. The maximum values were about 400-700m and 900-1400m, respectively, while the free gas content of shale showed an increasing trend. The gas-bearing model of shale with different TOC content was established. The gas storage capacity and the occurrence state of shale gas were affected by the content of TOC. The adsorption gas and free gas content of shale with lower TOC content were lower, and the gas storage potential was poor. The shale with high TOC content (12%) has lower porosity, lower capacity to provide effective storage space for free gas, and lower proportion of free gas. It is considered that the deep overpressure area will be the favorable direction of exploration and development of Permian shale gas in Lower Yangtze area.
【学位授予单位】：中国科学院研究生院(广州地球化学研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P618.13

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