特高渗疏松砂岩人造岩心的制作及评价

Preparation and evaluation on artificial core of extra high permeability unconsolidated sandstone

徐宏光 熊钰 王永清 周文胜 王玲 蒋倩

XU Hongguang XIONG Yu WANG Yongqing ZHOU Wensheng WANG Ling JIANG Qian

西南石油大学石油与天然气工程学院 中海油研究总院

College of Petroleum & Gas Engineering, Southwest Petroleum University, Chengdu 610500, Sichuan, China CNOOC Research Center, Beijing 100027, China

由于疏松砂岩胶结程度低、结构疏松、强度小，现场取心成本昂贵且难以成型，不适用于室内实验，因此提出制作特高渗疏松岩心代替部分储层岩心。为评价人造岩心的可靠性及代表性，从岩样的粒度组成、矿物成分、孔隙度、渗透率、胶结方式、胶结指数、孔隙结构、压缩系数、力学性质以及渗流特性等方面进行了研究。结果表明，压制压力越小、胶结物含量越少、水驱强度越大，岩石强度越低，岩石越疏松越容易破坏。岩心屈服应力随压制压力的减小呈幂函数降低，随胶结剂含量的减小呈对数降低，随水驱强度的增加呈对数减小。制备具有一定强度的特高渗疏松岩心至少需要压制压力4 MPa，胶结剂含量在5%左右。研制的疏松岩心在各方面与储层岩心相似，可代替储层岩心进行相关实验，同时为特高渗疏松岩心的研究提供借鉴。

Unconsolidated sandstone is characterized by low consolidation degree, loose structure and low strength. And besides, its coring cost is high and the cores cannot be shaped easily. As a result, the cores are not applicable to laboratory experiments. In this paper, it was proposed to make unconsolidated cores of extra high permeability to replace some reservoir cores. To evaluate the reliability and representativeness of artifcial cores, the rock samples were investigated from the aspects of size composition, mineral composition, porosity, permeability, consolidation mode, consolidation index, pore structure, compressibility coeffcient, mechanical property and percolation characteristic. It is indicated that the lower the pressing pressure and cement content are and the higher the water fooding strength is, the lower the rock strength is, the looser the rock is and the more easily it can be damaged. The yield stress decreases exponentially with the decreasing of pressing pressure, and logarithmically with the decreasing of cement content and the increasing of water fooding strength. To prepare extra high permeability unconsolidated cores with certain strength, the pressing pressure shall be at least 4 MPa and the cement content shall be about 5%. It is demonstrated that the artifcial unconsolidated core is similar with reservoir cores all around, and it can replace the reservoir core for experiments. It can be used as the reference for the investigation of ultra high permeability unconsolidated cores.

10.13639/j.odpt.2017.04.015