核磁共振冻融法表征非常规油气储层孔隙的适用性

发布时间：2018-10-08 18:50

【摘要】：核磁共振冻融法是当前非常规油气储层孔隙分布研究的一个热点技术,但因这类孔隙分布与成因复杂,使得该方法的适用性和准确性仍不很确定,是领域研究的难点。为加深对此的认识,采用核磁共振冻融法,结合相对传统的压汞法、氮气吸附法以及核磁共振T2法,分别对页岩、煤、致密砂岩3类端元非常规储层样品进行了孔径分布特征测试对比研究。结果表明,核磁共振冻融法在表征非常规储层纳米孔隙分布特征方面具有很好的适用性和准确性,但样品和实验条件也在一定程度上影响着测试精度,如制样大小、探针液体的KGibbs-Thomson(KGT)、冻融损伤以及金属矿物(黄铁矿)的含量等。因此实际分析中需根据研究对象选择合适颗粒大小的样品进行测定,需首先计算得出适合待测样品的KGT,需要探索新的探针液体,而因大多数非常规储层样品中的黄铁矿含量较低(10%),所以测试结果仍能够比较完整定量地刻画孔隙。核磁共振冻融法对于表征非常规储层孔隙很有潜力,其适用性和准确性还需进一步探索。
[Abstract]:Nuclear magnetic resonance freeze-thaw method is a hot technique in the study of pore distribution in unconventional oil and gas reservoirs. However, due to the complexity of pore distribution and origin, the applicability and accuracy of this method are still uncertain, which is a difficult point in the field of research. In order to get a better understanding of this problem, nuclear magnetic resonance freeze-thaw method, combined with conventional mercury injection, nitrogen adsorption and nuclear magnetic resonance T2 method, were used to separate shale and coal, respectively. The pore size distribution characteristics of 3 types of tight sandstone unconventional reservoir samples were tested and compared. The results show that nuclear magnetic resonance freeze-thaw method has good applicability and accuracy in characterizing the distribution of nano-pores in unconventional reservoirs, but the sample and experimental conditions also affect the measurement accuracy to a certain extent, such as the size of the sample preparation. The KGibbs-Thomson (KGT), freezing and thawing damage of probe liquid and the content of metallic minerals (pyrite) etc. Therefore, it is necessary to choose the appropriate particle size sample to be determined according to the object of study in the practical analysis. First, the KGT, suitable for the sample to be tested should be calculated and a new probe liquid should be explored. However, the content of pyrite in most unconventional reservoir samples is relatively low (10%), so the test results can still depict pores completely and quantitatively. Nuclear magnetic resonance freeze-thaw method has great potential in characterizing the porosity of unconventional reservoirs, and its applicability and accuracy need to be further explored.
【作者单位】：南京大学地球科学与工程学院;
【基金】：国家重点基础研究发展计划(973)项目“陆相页岩油储集空间与发育模式”(2014CB239102) 国家重大科技专项(2016ZX05002-006-005) 国家自然科学基金项目(No.41372127、No.41772128)资助
【分类号】：P618.13

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