Method for preparing rock core for shale experiments

Abstract

The invention provides a method for preparing a rock core for shale experiments. The method includes the following steps that 1, drilling is conducted on actual stratum shale or outcrop rock to obtain a rock core column;2, crack making is conducted on the rock core column; 3, according to the thickness of a crack which needs to be simulated, a plurality of sheet-shaped objects with the same thickness are made, and the sheet-shaped objects are uniformly arranged on the surface of the crack; 4, the rock core column is folded and sealed by gel; 5, a wrapping layer capable of completely sealing the rock core column is wrapped outside the rock core column, and a rock core to be tested is prepared; 6, holedrilling is conducted on the upper and lower ends, in the extension direction of the crack, of the rock core to be tested till the end faces of the rock core column are exposed. By the adoption of the method, intrinsic structural features of the shale and wall-surface features of the crack under actual stratum conditions can be actually reproduced, so that results of crack plugging experiments are more accurate; the solidified wrapping layer and the rock core (column) are tightly wrapped, and when the experiments are conducted, results cannot be influenced by the generation of pressure penetration.

Description

technical field [0001] The invention relates to the field of petroleum engineering, in particular to a core preparation method in the study of shale fracture leakage and well wall instability. Background technique [0002] Different from the wellbore instability caused by conventional expansive shale with strong water sensitivity, shale reservoirs usually have low content of water-sensitive clay minerals and well-developed micro-fractures and beddings. During the drilling process of shale reservoirs, the drilling fluid filtrate is easy to invade along the micro-fractures and weak bedding planes, resulting in the continuous expansion and connection of fractures, resulting in the instability of the entire wellbore, resulting in accidents such as pipe sticking and backfill sidetracking. occur. In order to solve the problem of wellbore instability in shale reservoirs, it is necessary to strengthen the plugging performance of micro-fractures, effectively reducing or even prevent...

AI Technical Summary

Problems solved by technology

[0007] The above-mentioned core preparation methods have realized the simulation of shale and its fracture system to a certain extent, but the above-mentioned casting molding method, tempered glass method and steel block simulation method are quite different from shale under actual formation conditions, especially Unable to simulate shale pore roar characteristics, fracture wall roughness and heterogeneity, etc., resulting in large errors in experimental results

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