Method for testing viscosity reduction rate of mixed viscosity reducer

Abstract

The invention discloses a method for testing the viscosity reduction rate of a mixed viscosity reducer. The method comprises the following steps: 1, preparing a bentonite-based paste solution; 2, mixing polyethylene glycol with sodium gluconate according to a certain ratio; 3, putting the prepared bentonite-based paste solution in a test container, and adding the mixed viscosity reducer to the test container; 4, starting a stirrer to stir for a certain time, and determining the viscosity of the bentonite-based paste solution through a viscometer until the viscosity no longer changes; and 5, calculating for converting the measured viscosity data into viscosity reduction rate data, and analyzing the viscosity reduction rate data to obtain the viscosity reduction rate of the mixed viscosity reducer. The method allows the viscosity reduction rate of the mixed viscosity reducer to be rapidly tested, lays a foundation for the use of a composite viscosity reducer, and has the advantages of simple test steps, low test cost, convenience for a worker to operate, and accurate test result.

Description

technical field [0001] The invention relates to a method for testing the viscosity reduction rate of a mixed viscosity reducer. Background technique [0002] In addition to controlling the solid phase content, the means to control the thickening of drilling fluid is mainly to add a viscosity reducer to reduce the viscosity and shear force of the system so that it has a suitable rheology. Viscosity reducers are chemical agents that reduce viscosity and shear. Regardless of the necessity or the quantity used, viscosity reducer is one of the indispensable drilling fluid treatment agents in the drilling process, and it plays a very important role in adjusting the rheology of drilling fluid. [0003] During the use of drilling fluid, the network structure formed by clay particles in the drilling fluid is often strengthened due to reasons such as temperature rise, salt intrusion or calcium intrusion, increase in solid phase content, or failure of the treatment agent, resulting in...

AI Technical Summary

Problems solved by technology

In order to control the thickening of drilling fluid, polyphosphate viscosity reducers were used as early as the late 1930s. They have a good viscosity reduction effect at room temperature and low temperature, but they begin to decompose and fail at about 65°C

In the 1940s, tannin was widely used as a drilling fluid viscosity reducer, but it was only suitable for medium and deep wells

Lime drilling fluid treated with tannin and calcium lignosulfonate and gypsum drilling fluid treated with iron chromium lignosulfonate began to be used in the 1950s, but they had high-temperature solidification and high-temperature thickening problems respectively

For more than 30 years, this viscosity reducer has been monopolizing the market, but FCLS contains metal chromium ions, and the amount is quite large. Only about 2000 tons are needed for drilling a medium-sized oil field every year, which causes very serious pollution to the environment and groundwater

The successful development of sulfonated lignite and sulfonated tannin in the 1970s further improved the temperature resistance limit of the mud, but it is not resistant to salt and is only suitable for deep well and fresh water slurry

Due to the characteristics of the molecular structure of the anionic viscosity reducer, it is determined that while adjusting the rheology of the drilling fluid, it will weaken the inhibition of the drilling fluid to clay, increase the yield value of the drilling fluid, and make it difficult to achieve low solids.

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