塔里木盆地顺北特深碳酸盐岩储层天然裂缝实验评价及油气意义

Experimental evaluation and hydrocarbon significance of natural fractures in Shunbei ultra-deep carbonate reservoir, Tarim Basin

李映涛 汝智星 邓尚 林会喜 韩俊 张继标 黄诚

LI Yingtao RU Zhixing DENG Shang LIN Huixi HAN Jun ZHANG Jibiao HUANG Cheng

中国石化 石油勘探开发研究院, 北京 100083 中国石化 西北油田分公司, 乌鲁木齐 830013

SINOPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China SINOPEC Northwest Oil Field Company, Urumqi, Xinjiang 830013, China

塔里木盆地顺北特深碳酸盐岩走滑断控油气藏储量丰富，大型走滑断裂和天然裂缝是油气主要储存空间和流动通道，研究此类储层的天然裂缝发育特征具有重要的意义。以顺北地区5口钻井储层段39块灰岩样品和7块白云岩样品为研究对象，通过对实钻取心样品开展岩相薄片分析、天然裂缝精细描述和脆性实验评价，研究顺北储层天然裂缝发育主控因素和影响规律。顺北地区中、下奥陶统鹰山组和一间房组储层岩性为白云岩和灰岩，岩相包括颗粒灰岩、粒泥灰岩、泥粒灰岩、粘结岩、泥灰岩、硅化灰岩和粉细晶白云岩、中粗晶白云岩；在灰岩样品中，泥灰岩脆性指数和天然裂缝发育密度最高，粘结岩脆性指数和天然裂缝发育密度最低；在白云岩样品中，中粗晶白云岩的脆性指数高于粉细晶白云岩，且样品晶粒越粗，天然裂缝越发育。天然裂缝发育密度与岩石样品脆性指数之间存在明显正相关关系；白云岩的孔渗物性和脆性指数高于灰岩，在相同脆性指数条件下，灰岩的裂缝发育能力更强。因此，灰岩地层中的高脆性段更有可能成为顺北地区的地质甜点区。

There are abundant hydrocarbon resources in the strike-slip fault-controlled ultra-deep carbonate reservoirs in the Shunbei area, Tarim Basin. Large strike-slip faults and natural fractures are the main storage space and flow channel of hydrocarbon resources. It is of great significance to study the natural fracture development characteristics in such reservoirs. 39 limestone samples and 7 dolomite samples from 5 wells in Shunbei area are taken as research objects. Through the analysis of thin section of lithofacies, fine description of natural fractures and brittleness test evaluation of core samples, the main controlling factors and influence laws of natural fracture development in Shunbei reservoir are studied. It is found that the reservoir lithology of Middle and Lower Ordovician Yingshan Formation and Yijianfang Formation in Shunbei area is dolomite and limestone, and the lithofacies include grainstone, wackestone, packstone, boundstone, muddy limestone, silicified limestone, silty-fine crystal dolomite and medium-coarse crystal dolomite. In limestone samples, muddy limestone has the highest brittleness index and natural fracture development density, while boundstone has the lowest brittleness index and natural fracture development density. In dolomite samples, the brittleness index of medium-coarse crystalline dolomite is higher than that of silty-fine crystal dolomite, and the coarser the grains are, the more developed the natural fractures are. There is a positive correlation between the natural fracture development density and the brittleness index of rock samples. The porosity, permeability and brittleness index of dolomite are higher than those of limestone. Under the same brittleness index, the fracture development ability of limestone is stronger. Therefore, the highly brittle section of limestone stratum is more likely to be the geological sweet spot in Shunbei area.

国家自然科学基金企业创新发展联合基金项目 U21B2063

https://doi.org/10.11781/sysydz202303422