Temperature-resistant salt-resistant high-expansion plugging agent for plugging large cracks and preparation method thereof

Abstract

The invention discloses a temperature-resistant salt-resistant high-expansion plugging agent for plugging large cracks and a preparation method of the plugging agent. The plugging agent system comprises the following components in percentage by mass: 6-10% of a main agent, 0.6-1% of a cross-linking agent, 0.006-0.01% of an initiator, 6-14% of an additive and the balance of water, the preparation method provided by the invention comprises the following steps: adding montmorillonite into water to prepare a montmorillonite dispersion system; adding the main agent, the cross-linking agent and theinitiator into the montmorillonite dispersion system to prepare a main agent solution; putting the main agent solution into a drying oven at 90-120 DEG C to gelatinize for 9-48 hours; the gelatinizingstrength of the plugging agent system can reach the H level, the expansion multiple is 50-80 times, the strength after expansion is good, the water plugging effect is good under the conditions of 140DEG C and 250,000 mineralization degrees, and the plugging agent is suitable for profile control and water plugging operation of plugging large-crack water channeling channels of high-temperature andhigh-salinity oil reservoirs.

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-...

AI Technical Summary

Problems solved by technology

Although it has good thermal stability and high water shutoff rate, for high-temperature and high-salt oil reservoirs in western my country, this kind of polymer jelly still has many technical problems that need to be solved. Degradation, the structure is destroyed; high salinity will cause dehydration of jelly plugging agent in the formation, volume shrinkage, and reduction of plugging agent strength, etc.

CN 102040975 A discloses a silicate water blocking agent. Although it is convenient to configure and low in price, its strength is low, and the gelation time at high temperature is short, so the field application is limited

In addition, there is a gel composed of lignosulfonate, phenol, formaldehyde, and polymers. Due to the high toxicity of phenolic aldehydes, its use is also restricted on site, which is not conducive to environmental protection; and the gelation time, pH and temperature range are required. It has limitations and is not suitable for high temperature and high salinity reservoirs

Images