典型低渗碳酸盐岩储层微观孔隙结构特征与储层分类研究

发布时间：2018-04-25 19:58

  本文选题：低渗碳酸盐岩油藏 + 可动流体　； 参考：《中国科学院研究生院(渗流流体力学研究所)》2015年硕士论文

【摘要】：低渗碳酸盐岩油藏是我国在海外油气开发的重要油藏类型,该油藏储层微观孔喉结构复杂,与低渗砂岩油藏有明显的差异,急需进行低渗碳酸盐岩油藏储层评价方面的研究工作。由于低渗碳酸盐岩油藏孔洞缝发育非常复杂,常规储层评价的实验方法很难准确的对其评价。本文通过恒速压汞实验、核磁共振实验、启动压力梯度测试和油水两相渗流规律实验对A油田Sadi、Tanuma、 Khasib和Mishrif四个不同层位岩心进行了测试,并与低渗砂岩岩心数据进行了对比。同时,利用全直径岩心的CT扫描技术与核磁共振技术的结合,对不同孔隙发育类型的岩心进行了孔洞缝的特征分析,研究结果表明：(1)对于低渗透碳酸盐岩储层,喉道半径、孔喉半径比是决定储层物性的关键因素,在同渗透率等级下,低渗碳酸盐岩岩芯中大部分的喉道半径要比低渗砂岩岩芯要小,孔道半径整体大于砂岩岩心。不同渗透率级别的低渗碳酸盐岩岩芯,孔道半径的峰值变化不大,但是展布范围差别明显,喉道半径分布差异显著,平均喉道半径、平均孔喉比与渗透率呈良好的幂函数关系。(2)核磁共振测试结果表明：低渗碳酸盐岩储层T2谱呈现出单峰、双峰和多峰的结构,T2弛豫时间的最大值高于同渗透率级别的砂岩。随着渗透率的增加,可动流体百分数、可动流体孔隙度增大,相关性变好,渗透率越低,非均质性越强。(3)将全直径岩心CT扫描与核磁共振技术结合,建立了针对裂缝型、孔洞型、孔隙型三种孔隙类型的识别方法,提高了针对低渗碳酸盐岩储层孔隙结构分析的精确性。其中裂缝型储层的核磁共振T2弛豫时间主要分布在10～1000ms,孔洞型储层的核磁共振T2弛豫时间主要分布在1-1000ms,孔隙型储层的核磁共振T2弛豫时间主要分布在1-100ms。(4)通过水测启动压力梯度测试,对于同一渗透率级别的岩样进行对比。随着样品渗透率增大,水测启动压力梯度逐渐减小,且降低幅度逐渐减弱。水测真实启动压力梯度和水测拟启动压力梯度与渗透率均存在很好的幂函数关系,是储层综合评价的一个重要参数。(5)在油水相对渗透率测试实验中,通过考虑油、水粘度以及水相的有效渗透率,分别计算得到了不同储层不同渗透率级别的油、水相最大流度,通过该流度反映并对比了不同储层间油水两相流动难易程度。(6)根据研究的A油田低渗碳酸盐岩储层特性,结合传统的孔渗油藏分类方法,提出了低渗碳酸盐岩油藏四元分综合分类系数,对中东A油田的低渗碳酸盐岩不同储层进行分类评价,评价结果为Mishrif为Ⅰ类、Sadi和Tanuma为Ⅱ类、Khasib为Ⅲ类。
[Abstract]:Low permeability carbonate reservoir is an important reservoir type in overseas oil and gas development in our country. The micro pore throat structure of this reservoir is complex, and it is obviously different from low permeability sandstone reservoir. There is an urgent need for research on reservoir evaluation of low permeability carbonate reservoirs. Due to the complex development of pore fractures in low permeability carbonate reservoirs, it is difficult to evaluate them accurately by conventional reservoir evaluation methods. In this paper, four layers of cores, Sadiang Tanuma, Khasib and Mishrif, are tested by means of constant velocity mercury injection experiment, nuclear magnetic resonance test, starting pressure gradient test and oil-water two-phase percolation rule experiment, and are compared with the low-permeability sandstone core data. At the same time, with the combination of CT scanning and nuclear magnetic resonance (NMR) technology of full-diameter cores, the characteristics of pore fractures in cores with different pore development types are analyzed. The results show that the throat radius of low permeability carbonate reservoirs is determined by the study. The pore throat radius ratio is the key factor to determine the reservoir physical properties. Under the same permeability level, the throat radius of most of the low permeability carbonate core is smaller than that of the low permeability sandstone core, and the overall pore radius is larger than the sandstone core. In low permeability carbonate cores with different permeability levels, the peak value of pore radius does not change much, but the distribution of throat radius is obviously different, and the average throat radius is different. The results of nuclear magnetic resonance (NMR) showed that the T2 spectrum of low permeability carbonate reservoir showed a single peak, two peaks and multiple peaks, and the maximum value of T2 relaxation time was higher than that of sandstone of the same permeability level. With the increase of permeability, the percentage of movable fluid and the porosity of movable fluid increase, and the correlation becomes better. The lower the permeability, the stronger the heterogeneity. The accuracy of pore structure analysis for low permeability carbonate reservoir is improved by identifying three pore types. Among them, the NMR T2 relaxation time of fractured reservoir is mainly distributed in 10 ~ 1000ms, that of porosity reservoir is mainly distributed between 1-1000ms, and that of porous reservoir is mainly distributed between 1-100ms.Ni4) Dynamic pressure gradient test, The rock samples of the same permeability level are compared. With the increase of sample permeability, the starting pressure gradient of water measurement decreases gradually, and the decreasing amplitude decreases gradually. There is a good power function relationship between real start-up pressure gradient and pseudo-start-up pressure gradient and permeability, which is an important parameter in reservoir comprehensive evaluation. The water viscosity and the effective permeability of the water phase are calculated respectively to obtain the oil with different permeability levels in different reservoirs and the maximum mobility of the water phase. The mobility reflects and contrasts the difficulty degree of oil-water two-phase flow between different reservoirs. According to the characteristics of low-permeability carbonate reservoir in A oilfield studied, combined with the traditional classification method of pore and permeability reservoir, This paper presents a comprehensive classification coefficient of four elements for low permeability carbonate reservoir, and evaluates the different reservoirs of low permeability carbonate rock in Middle East A oilfield. The results show that Mishrif is class 鈪，

本文编号：1802733