A temperature-resistant and salt-resistant high-expansion plugging agent for sealing large cracks and its preparation method

Abstract

The invention discloses a temperature-resistant, salt-resistant, high-expansion plugging agent for sealing large cracks and a preparation method thereof. The agent system is composed of the following components in mass percentage: main agent 6%-10%, crosslinking agent 0.6% ~1%, initiator 0.006%~0.01%, additive 6%~14%, all the other are water; The preparation method provided by the invention comprises the following steps: adding montmorillonite to water to prepare montmorillonite dispersion system; Add the crosslinking agent and initiator to the montmorillonite dispersion system to prepare the main agent solution; put the main agent solution in an oven at 90-120°C to make it gel for 9-48 hours, and the gelling strength of this agent system can reach H level. The expansion multiple is 50-80 times, the strength after expansion is good, and the water shutoff effect is good under the conditions of 140°C and salinity of 250,000. The present invention is suitable for profile control and water shutoff in high temperature and high salt reservoirs to seal large fracture water channeling channels Operation.

Description

technical field

[0001] The invention relates to the technical field of oil and gas field development, in particular to a temperature-resistant and salt-resistant high-expansion plugging agent for sealing large fractures and a preparation method thereof. Background technique

[0002] High-temperature and high-salt reservoirs generally have high temperature (90-150°C) and high salinity (12×10 4 -20×10 4 mg / L), traditional plugging agents tend to have problems such as poor stability, easy dehydration, and poor strength under the conditions of high-temperature and high-salt reservoirs. When performing water plugging operations, if the strength of the plugging agent is not enough, there will be a series of problems such as high water content after water plugging, rapid decline in oil well production after recovery, and short validity period. The water shutoff effect in fractured-cavity reservoirs is one of the key factors for improving recovery and reducing costs in high water-...

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