核磁共振测井正反演方法研究及其在鄂尔多斯盆地南部的应用

发布时间：2018-01-11 12:41

本文关键词：核磁共振测井正反演方法研究及其在鄂尔多斯盆地南部的应用　出处：《中国地质大学》2017年博士论文　论文类型：学位论文

【摘要】：鄂尔多斯盆地南部长8目的层属于典型致密砂岩储层,孔隙结构复杂,且发育大量微裂缝,非均质性强烈,导致核磁共振测井响应受影响、特征模糊;T2谱反演没有适合研究区的统筹优化方案;核磁测井进行储层评价仍存在疑问,尤其裂缝储层渗透率评价是难点。为此,急需进一步研究来解决这些问题。总结了研究区目的层的岩石学和物性特征,主要发育宽度小于0.2mm的高角度裂缝;总结了P型核磁共振测井方法和仪器特征。基于研究区影响因素,建立核磁测井正演模型和方法,模拟发现孔隙结构变好通常会使T2谱整体向长弛豫成分移动,峰值明显变大但形状大致相似;研究区T2谱通常可指示界面和地层特征;储层饱含单相不同流体时T2谱相似,随油气饱和度增大,油水两相T2谱逐渐由单水峰向双峰、单油峰变化,气水两相T2谱幅度明显下降;研究区裂缝和碳酸盐岩胶结物对T2谱影响可忽略。针对T2谱反演,实现常用算法并分析影响因素,取长补短建立了研究区T2谱反演的统筹优化方案。先建立适合不同T2谱特征的最优布点方案,后基于BG理论与截止值最小准则选取截止值,再利用奇异值分解法(SVD)解得T2谱作为联合迭代重建算法(SIRT)初值,迭代反演最终T2谱。结合研究区核磁共振测井认识和方法,对比后优选了合适的识别流体、流体饱和度和孔径分布评价方法。重点研究了含裂缝致密砂岩储层中裂缝和基质双孔隙系统的渗透率评价方案。在无裂缝致密砂岩储层,建立了适用的基于HFU(水力流动单元)和FZI(流动带指标)理论分类地层的核磁测井渗透率模型。在裂缝致密砂岩层段,提出了裂缝和基质双孔隙系统渗透率评价的两类新方法,一类是快速估算新方法,即双侧向裂缝模型计算的裂缝渗透率与HFU和FZI理论分类地层核磁测井渗透率模型计算的基质渗透率二者之和;第二是裂缝新响应方程与渗透率理论模型,先建立该双孔隙系统的裂缝双侧向测井新响应方程,并提出虚拟岩心方案建立裂缝胶结指数和基质胶结指数计算模型,最终建立了裂缝参数非线性方程,即裂缝新渗透率理论模型。正演弄清了研究区核磁共振测井响应特征。反演实验表明统筹优化方案T2谱反演效率和精度综合最佳,优于其他常用截止值法和反演算法,且其最优布点方案可改善其他方法精度。应用中优选了差谱法识别流体,T2截止值法分析流体饱和度,并刻度了储层孔径分布评价模型,与录井或实验结果对应良好。研究区裂缝致密砂岩渗透率评价表明,新理论模型精度最高,可作为裂缝和基质双孔隙系统渗透率的精确评价方法;而快速估算新方法次之,适合测井现场快速分析。综上,基于核磁测井响应特征,建立了适合研究区的T2谱反演统筹优化方案、评价模型和裂缝致密砂岩渗透率快速和精确评价方法,提高了研究区含裂缝致密砂岩储层评价的精度和效率,可为致密砂岩测井评价提供参考并推广应用。
[Abstract]:Minister of South Ordos basin belongs to the typical 8 layers of tight sandstone reservoir, complex pore structure, and the development of a large number of micro cracks, strong heterogeneity, affected, NMR logging response characteristics of fuzzy optimization; T2 spectrum inversion scheme is not suitable for the study area; reservoir evaluation of nuclear magnetic logging doubt still exists, especially the crack reservoir evaluation is difficult. Therefore, further research needs to solve these problems. This paper summarizes the characteristics of petrology and physical properties of the target layer, the main development of high angle width less than 0.2mm crack; summarizes the P NMR logging method and instrument characteristics. The influencing factors based on the study area, the establishment of NMR logging forward model and the method of simulation shows that the pore structure becomes good usually makes overall T2 spectrum to the long relaxation peak components, significantly larger but similar shape; study area usually indicates T2 spectrum The interface and stratigraphic characteristics; reservoir with different fluid phase T2 spectrum is similar with the oil and gas saturation increases, the oil-water two-phase T2 spectrum gradually from single water peak to Shuangfeng, single peak oil changes, gas water two-phase T2 spectral amplitude decreased significantly; the study area cracks and carbonate cements on T2 spectrum effect can be neglected. For T2 the spectral inversion, commonly used algorithm and analyze the influence factors, established the optimization scheme of each district T2 spectrum inversion. To establish the optimal T2 spectrum characteristics for different layout scheme, based on the theory of BG and the minimum cut-off value criterion of selecting the cutoff value, then using singular value decomposition (SVD) solution as the joint spectrum of T2 the initial value of the iterative reconstruction algorithm (SIRT), the final iterative inversion of T2 spectrum. Combined with NMR logging understanding and methods of the study area, after comparing the optimized identification of fluid suitable, fluid saturation and pore size distribution evaluation method. Focus on the cracked The evaluation scheme of joint fracture and matrix permeability of tight sandstone reservoir in double porosity system. No cracks in the tight sandstone reservoir, was established based on HFU application (hydraulic flow unit) and FZI (flow zone index) NMR permeability model theory classification strata. Cracks in the tight sandstone reservoir, puts forward two kinds of new the method of fracture and matrix dual porosity system permeability evaluation, is a new rapid estimation method, calculated the bilateral matrix permeability calculation to crack model in fracture permeability with HFU and FZI classification theory formation NMR logging permeability model two and second are new; crack response equation and permeability model, the establishment of bilateral first crack double porosity system to the new logging response equation, and puts forward the scheme of establishing the virtual core crack cementation index and matrix cementation index calculation model, finally established the non linear fracture parameters That is, a new theoretical model of crack permeability. The forward made the NMR logging response characteristics of the study area. Experiments show that the optimization inversion scheme of T2 spectrum inversion efficiency and precision of comprehensive best method and the inverse algorithm is better than other commonly used cutoff value, and the optimal layout scheme can improve the accuracy of other methods. Application of optimized differential spectrum method identification of fluid, T2 cutoff value analysis method of fluid saturation, and the scale of the reservoir pore size distribution evaluation model, and corresponding logging or good experimental results. Studies show that the fracture permeability of tight sandstone evaluation, a new theoretical model of the highest accuracy, can be used as a precise evaluation of fracture and matrix dual porosity system and rapid permeability method; a new method of estimating time the suitable logging site fast analysis. In summary, based on the NMR logging response characteristics, suitable for the study area T2 spectrum inversion optimization scheme is established, the evaluation model and crack Fast and accurate permeability evaluation method for tight sandstone can improve the accuracy and efficiency of evaluation for fractured tight sandstone reservoirs in the study area, and provide reference for the evaluation of tight sandstone logging and promote its application.

【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P618.13;P631.81

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