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疏松砂岩具有胶结性差,结构疏松及强度小的特征,现场往往采用铅封和冷冻取心,不仅成本高,而且难以获得代表性成型岩心,铅封岩心还存在测试结果不准确的问题,故为此研究了一种弱胶结高渗疏松砂岩岩心制作新技术.在不改变粒度组成及胶结剂用量的条件下,选用与储层粒径分布相似的河沙作为骨架颗粒时,加入一定量的地层水可较好的控制岩心胶结程度,且不需要扩孔,岩心较容易成型,制作岩心的渗透率范围为1000~3700mD,润湿性符合河流沉积砂岩特征.研究认为地层水是制作疏松砂岩岩心的主控因素,通过对比天然岩心和人造岩心的孔隙度、渗透率、胶结方式和胶结指数等参数,添加地层水制作的岩心胶结性和孔渗较好,与天然岩心有较高的相似性,制作的岩心可用于室内实验研究,表明此制作技术可行.
Unconsolidated sandstone has the characteristics of poor cementation, loose structure and low strength. The lead seal and the frozen coring are often adopted in the site. It is not only high in cost but also difficult to obtain the representative shaped core. The lead seal core also has the problem of inaccurate test results. In this paper, a new technology for producing weakly cemented and unconsolidated sandstone cores is studied.When the sand with similar distribution of reservoir particle size is used as the skeleton particles, a certain amount of formation is added without changing the particle size composition and the amount of cement. Water can better control the degree of core cementing, and does not need to expand the hole, the core is easier to shape, the production of core permeability range of 1000 ~ 3700mD, wettability consistent with river sedimentary sandstone characteristics .Studies that the formation of water is loose sandstone core By contrasting the porosity, permeability, cementation and cementation index of natural core and artificial core, the core caking and pore infiltration made by adding formation water are better and have higher similarity with natural core , Making the core can be used for laboratory experiments, indicating that this production technology is feasible.