鄂尔多斯盆地东部本溪组煤系致密砂岩储层脆性评价

Brittleness Evaluation of Tight Sandstone Reservoirs in Benxi Formation Coal Measures in Eastern Ordos Basin

致密砂岩储层的特性决定了脆性评价工作在其勘探开发过程中的重要性。研究区块内的脆性矿物为石英、碳酸盐矿物和黄铁矿,但不同矿物组分对于脆性贡献存在差异。为了更准确地衡量脆性,利用全岩矿物和黏土矿物X衍射实验、三轴岩石力学实验和特殊测井资料,提出一种基于改进灰色关联理论的新型评价方法。新方法能够将矿物组分对于脆性的贡献量化,结果显示石英为0.807、黄铁矿为0.758、碳酸盐矿物为0.496、黏土矿物为-0.896。通过对3种方法计算结果的比较,研究发现新方法既与原方法具有较好一致性,又弥补了原有2种方法在部分情况下计算存在较大差异的问题,这显示了其一定的优越性。利用该方法可以得到连续性的脆性剖面,对于现场射孔压裂施工具有一定的指导意义。

The characteristics of tight sandstone reservoirs determine the importance of brittleness evaluation work in their exploration and development process. The brittle minerals in the study block are quartz, carbonate minerals and pyrite, but there are differences in the contribution of different mineral fractions to the brittleness. In order to measure the brittleness more accurately, proposes a new evaluation method based on improved gray correlation theory using whole-rock mineral and clay mineral X-ray diffraction experiments, triaxial rock mechanics experiments and special logging data.The new method can quantify the contribution of mineral components to brittleness, and the results show 0.807 for quartz, 0.758 for pyrite, 0.496 for carbonate minerals, and-0.896 for clay minerals. By comparing the calculation results of the three methods, it is found that the new method is in good agreement with the original method, and also compensates for the large difference in calculation between the original two methods in some cases. This shows its certain superiority. The method can be used to obtain a continuous brittle which is a guideline for the construction of field injection fracturing.