Direct making method of large model fracture core maintaining original oil-water saturation

Abstract

The invention discloses a direct making method of a large model fracture core maintaining original oil-water saturation. The method includes: (1) determining the volume V, porosity phi, permeability K, oil saturation So, water saturation Sw and the like of a fracture core; (2) preparing simulated oil according to a stratum oil-water viscosity ratio, and determining the used oil mass mo=Vo*rhoo; (3) under the circumstance of no consideration of oil saturation, acquiring mass of the used water, cement and quartz sand, i.e. a, b and c respectively; (4) while establishing oil saturation, acquiring the mass of water mw=a-Vo*rhow; (5) mixing oil, water and an emulsifier evenly to prepare a oil-in-water emulsion; (6) adding cement and quartz sand into the emulsion and stirring the substances evenly to obtain a cement slurry; (7) when a cement sample is in a semi-solidified state, cutting the cement sample according to an experiment required fracture direction with steel wire; and (8) solidifying the cement sample to the end. The method provided by the invention is low in cost and convenient to operate, can control the distribution of fracture in the core, and realizes simultaneous establishment of the model and saturation.

Description

technical field [0001] The invention relates to a direct manufacturing method for maintaining the original oil-water saturation of a large-model fractured rock core in an indoor simulation experiment of petroleum exploration and development. Background technique [0002] Physical simulation is an important means to simulate the development of oil and gas reservoirs. Practice shows that the larger the geometric size of the model, the closer the experimental results are to the actual mine field. Experimental cores are divided into natural and man-made. It is difficult to obtain natural cores, and the cost is relatively high. Therefore, artificial cores are commonly used for physical simulation of large models. The sand-packing model has low working pressure and cannot simulate fracture-porous reservoirs. Epoxy resin and aluminum phosphate are commonly used as cementing agents for existing cementation models, most of which require high-temperature sintering. In order to be...

AI Technical Summary

Problems solved by technology

For fractured cores, the procedure of creating fractures first and then establishing saturation is generally adopted. When the fluid is saturated, the fluid will channel through the fractures, so the original water saturation cannot be established.

There are two main methods for making cracks on artificial large cores. One is to insert a metal sheet before the core is formed, and then pull it out to form cracks, but it is difficult to grasp the timing of pulling out.

The second is to use specific materials to be placed in the model in advance, to melt, dissolve, volatilize, etc. by physical means, but there will be residues and the process is more cumbersome

Due to the existence of fractures in the fractured core, the water saturation is often higher than the required value, and the required oil-water saturation cannot be established